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Microphysical Properties of Single and Mixed-Phase Arctic Clouds...
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Abstract A novel new approach to retrieve cloud microphysical properties from mixed-phase clouds is presented. This algorithm retrieves cloud optical depth, ice fraction, and...
Ice properties of single-layer stratocumulus during the Mixed-Phase Arctic Cloud Experiment
E-Print Network (OSTI)
Ice properties of single-layer stratocumulus during the Mixed-Phase Arctic Cloud Experiment: 2 opportunity to study poorly understood ice formation processes in mixed-phase stratocumulus. Using, were not significant sources of ice based on parameterizations from existing studies. After surveying
Arctic mixed-phase cloud properties derived from surface-based sensors at SHEBA
Mixed-phase clouds are an understudied component of global cloudiness and are thus poorly represented in models at all scales, which typically partition cloud phase as a function of temperature. The proper partitioning of cloud phase is particularly important considering the unique radiative properties of liquid droplets and ice particles, the impact of phase on precipitation processes, and the sensitivity of phase
M. D. Shupe; S. Y. Matrosov; T. Uttal
Microphysical Properties of Single and Mixed-Phase Arctic Clouds Derived from AERI Observations
SciTech Connect
A novel new approach to retrieve cloud microphysical properties from mixed-phase clouds is presented. This algorithm retrieves cloud optical depth, ice fraction, and the effective size of the water and ice particles from ground-based, high-resolution infrared radiance observations. The theoretical basis is that the absorption coefficient of ice is stronger than that of liquid water from 10-13 mm, whereas liquid water is more absorbing than ice from 16-25 um. However, due to strong absorption in the rotational water vapor absorption band, the 16-25 um spectral region becomes opaque for significant water vapor burdens (i.e., for precipitable water vapor amounts over approximately 1 cm). The Arctic is characterized by its dry and cold atmosphere, as well as a preponderance of mixed-phase clouds, and thus this approach is applicable to Arctic clouds. Since this approach uses infrared observations, cloud properties are retrieved at night and during the long polar wintertime period. The analysis of the cloud properties retrieved during a 7 month period during the Surface Heat Budget of the Arctic (SHEBA) experiment demonstrates many interesting features. These results show a dependence of the optical depth on cloud phase, differences in the mode radius of the water droplets in liquid-only and mid-phase clouds, a lack of temperature dependence in the ice fraction for temperatures above 240 K, seasonal trends in the optical depth with the clouds being thinner in winter and becoming more optically thick in the late spring, and a seasonal trend in the effective size of the water droplets in liquid-only and mixed-phase clouds that is most likely related to aerosol concentration.
Turner, David D.
Parameterization of ice cloud radiative properties and its application to the potential climatic importance of mixed-phase clouds
It is often assumed, in modeling and radiation budget simulation, that clouds below the cirrus level are entirely in the liquid phase. There is substantive evidence from observations that low and middle clouds are often of mixed phase. Using a light-scattering program for hexagonal crystals, the authors update a parameterization of the radiative properties of ice clouds from an earlier study and use the new parameterization to investigate the role of mixed-phase clouds in three areas: (i) the interpretation of ISCCP optical depth, (ii) the simulation of the earth radiation budget, and (iii) the sensitivity of a simple radiative-convective model to an increase in CO{sub 2}. In all cases, mixed-phase clouds are shown to have the potential to significantly modify the results obtained using liquid phase clouds. A precise quantification is not yet possible as the dependence of the fraction of ice and liquid water is mixed-phase clouds on atmospheric properties, and the way in which the ice and liquid water are mixed, are not known with sufficient detail. 43 refs., 17 figs., 2 tabs.
Sun, Z.; Shine, K.P. [Univ. of Reading (United Kingdom)] [Univ. of Reading (United Kingdom)
Parameterization of Ice Cloud Radiative Properties and Its Application to the Potential Climatic Importance of Mixed-Phase Clouds
Science Conference Proceedings (OSTI)
It is often assumed, in modeling and radiation budget simulation, that clouds below the cirrus level are entirely in the liquid phase. There is substantive evidence from observations that low and middle clouds are often of mixed phase. Using a ...
Zhian Sun; Keith P. Shine
Towards a Characterization of Arctic Mixed-Phase Clouds
Towards a Characterization of Arctic Mixed-Phase Clouds Towards a Characterization of Arctic Mixed-Phase Clouds Shupe, Matthew CIRES/NOAA/ETL Kollias, Pavlos Brookhaven National Laboratory Category: Cloud Properties Mixed-phase clouds play a unique role in the Arctic, where the delicate balance of phases in these clouds can have a profound impact on the surface radiation balance and various cloud-atmosphere-radiation-surface feedback processes. A better understanding of these clouds is clearly important and has been a recent objective of the ARM program. To this end, multiple sensors including radar, lidar, and temperature soundings, have been utilized in an automated cloud type classification scheme for clouds observed at the North Slope of Alaska site. The performance of this new algorithm at identifying mixed-phase cloud conditions is compared with an
Intercomparison of model simulations of mixed-phase clouds observed during the ARM Mixed-Phase Arctic Cloud Experiment. Part I: Single layer cloud
simulation that is in the ice-phase. Note that the y-axis isradiative properties of ice and mixed-phase clouds. Quart.include liquid-phase only, ice-phase only, and mixed-phase.
Klein, Stephen A.
The Mixed-Phase Arctic Cloud Experiment
The Mixed-Phase Arctic Cloud Experiment (M-PACE) was conducted from 27 September through 22 October 2004 over the Department of Energy's Atmospheric Radiation Measurement (ARM) Climate Research Facility (ACRF) on the North Slope of Alaska. The ...
J. Verlinde; J. Y. Harrington; V. T. Yannuzzi; A. Avramov; S. Greenberg; S. J. Richardson; C. P. Bahrmann; G. M. McFarquhar; G. Zhang; N. Johnson; M. R. Poellot; J. H. Mather; D. D. Turner; E. W. Eloranta; D. C. Tobin; R. Holz; B. D. Zak; M. D. Ivey; A. J. Prenni; P. J. DeMott; J. S. Daniel; G. L. Kok; K. Sassen; D. Spangenberg; P. Minnis; T. P. Tooman; M. Shupe; A. J. Heymsfield; R. Schofield
Small Cloud Particle Shapes in Mixed-Phase Clouds
The shapes of cloud particles with maximum dimensions Dmax between 35 and 60 ?m in mixed-phase clouds were studied using high-resolution particle images collected by a cloud particle imager (CPI) during the Mixed-Phase Arctic Cloud Experiment (M-...
Greg M. McFarquhar; Junshik Um; Robert Jackson
Vertical Motions in Arctic Mixed-Phase Stratiform Clouds
The characteristics of Arctic mixed-phase stratiform clouds and their relation to vertical air motions are examined using ground-based observations during the Mixed-Phase Arctic Cloud Experiment (MPACE) in Barrow, Alaska, during fall 2004. The ...
Matthew D. Shupe; Pavlos Kollias; P. Ola G. Persson; Greg M. McFarquhar
Mixed-Phase Cloud Retrievals Using Doppler Radar Spectra
Mixed-Phase Cloud Retrievals Using Mixed-Phase Cloud Retrievals Using Doppler Radar Spectra M. D. Shupe, S. Y. Matrosov, and T. L. Schneider National Oceanic and Atmospheric Administration Environmental Technology Laboratory Boulder, Colorado P. Kollias Rosentiel School of Marine Atmospheric Sciences University of Miami Miami, Florida Introduction The radar Doppler spectrum contains a wealth of information on cloud microphysical properties. Typically, radar-based cloud retrievals use only the zeroth or first moments of the Doppler spectrum - reflectivity and mean Doppler velocity - to derive quantities such as cloud water content and particle characteristic size (e.g., Liou and Sassen 1994; Matrosov et al. 2002). When using only the moments of the Doppler spectrum, important spectral information can be lost, particularly when the spectrum is
Mixed phase clouds, cloud electrification and remote sensing.
Most of hypothesis trying to explain charge separation in thunderstorm clouds require presence of ice and supercooled water. Thus the existence of ice or at least mixed phase regions near cloud tops should be a necessary (but not a sufficient) condition for development of lightning. We show that multispectral satellite based instruments, like the DOE MTI (Multispectral Thermal Imager) or NASA MODIS (Moderate Resolution Imaging Spectroradiometer), using the near infrared and visible spectral bands are able to distinguish between water, ice and mixed phase cloud regions. An analysis of the MTI images of mixed phase clouds - with spatial resolution of about 20 m - shows regions of pure water, pure ice as well as regions of water/ice mixtures. We suggest that multispectral satellite instruments may be useful for a short time forecast of lightning probabilities.
Chylek, P. (Petr); Borel, C. C. (Christoph C.); Klett, James
The Vertical Profile of Liquid and Ice Water Content in Midlatitude Mixed-Phase Altocumulus Clouds
The microphysical properties of mixed-phase altocumulus clouds are investigated using in situ airborne measurements acquired during the ninth Cloud Layer Experiment (CLEX-9) over a midlatitude location. Approximately ? of the sampled profiles are ...
Lawrence D. Carey; Jianguo Niu; Ping Yang; J. Adam Kankiewicz; Vincent E. Larson; Thomas H. Vonder Haar
Arctic Mixed-Phase Cloud Properties Derived from Surface-Based Sensors at SHEBA MATTHEW D. SHUPE AND SERGEY Y. MATROSOV
, cloud-top liquid layer from which ice particles formed and fell, although deep, multilayered mixed-phase. These values are all larger than those found in single-phase ice clouds at SHEBA. Vertically resolved cloud phases can coexist is in question. A re- view of model parameterizations shows the lower tem- perature
Shupe, Matthew
Comparison of Aircraft Observations with Mixed-Phase Cloud Simulations
In order to provide guidance for the further improvement of a mixed-phase cloud scheme being developed for use in an NWP model, comparisons of dynamical, thermodynamical, and microphysical variables between in situ aircraft data and model data ...
Paul A. Vaillancourt; Andr� Tremblay; Stewart G. Cober; George A. Isaac
A Focus On Mixed-Phase Clouds
The phase composition and microphysical structure of clouds define the manner in which they modulate atmospheric radiation and contribute to the hydrologic cycle. Issues regarding cloud phase partitioning and transformation come to bear directly ...
Matthew D. Shupe; John S. Daniel; Gijs de Boer; Edwin W. Eloranta; Pavlos Kollias; Edward P. Luke; Charles N. Long; David D. Turner; Johannes Verlinde
Using Surface Remote Sensors to Derive Mixed-Phase Cloud Radiative Forcing:
Using Surface Remote Sensors to Derive Mixed-Phase Cloud Radiative Forcing: Using Surface Remote Sensors to Derive Mixed-Phase Cloud Radiative Forcing: An Example from M-PACE Title Using Surface Remote Sensors to Derive Mixed-Phase Cloud Radiative Forcing: An Example from M-PACE Publication Type Journal Article Year of Publication 2011 Authors de Boer, Gijs, William D. Collins, Surabi Menon, and Charles N. Long Journal Atmospheric Chemistry and Physics Volume 11 Start Page 11937 Pagination 11937-11949 Abstract Measurements from ground-based cloud radar, high spectral resolution lidar and microwave radiometer are used in conjunction with a column version of the Rapid Radiative Transfer Model (RRTMG) and radiosonde measurements to derive the surface radiative properties under mixed-phase cloud conditions. These clouds were observed during the United States Department of Energy (US DOE) Atmospheric Radiation Measurement (ARM) Mixed-Phase Arctic Clouds Experiment (M-PACE) between September and November of 2004. In total, sixteen half hour time periods are reviewed due to their coincidence with radiosonde launches. Cloud liquid (ice) water paths are found to range between 11.0-366.4 (0.5-114.1) gm-2, and cloud physical thicknesses fall between 286-2075 m. Combined with temperature and hydrometeor size estimates, this information is used to calculate surface radiative flux densities using RRTMG, which are demonstrated to generally agree with measured flux densities from surface-based radiometric instrumentation. Errors in longwave flux density estimates are found to be largest for thin clouds, while shortwave flux density errors are generally largest for thicker clouds. A sensitivity study is performed to understand the impact of retrieval assumptions and uncertainties on derived surface radiation estimates. Cloud radiative forcing is calculated for all profiles, illustrating longwave dominance during this time of year, with net cloud forcing generally between 50 and 90 Wm-2.
Limitations of the Wegener�Bergeron�Findeisen Mechanism in the Evolution of Mixed-Phase Clouds
Phase transformation and precipitation formation in mixed-phase clouds are usually associated with the Wegener�Bergeron�Findeisen (WBF) process in which ice crystals grow at the expense of liquid droplets. The evolution of mixed-phase clouds, ...
Alexei Korolev
Mesoscale Modeling During Mixed-Phase Arctic Cloud Experiment
Mixed-phase arctic stratus clouds are the predominant cloud type in the Arctic (Curry et al. 2000) and through various feedback mechanisms exert a strong influence on the Arctic climate. Perhaps one of the most intriguing of their features is that they tend to have liquid tops that precipitate ice. Despite the fact that this situation is colloidally unstable, these cloud systems are quite long lived - from a few days to over a couple of weeks. It has been hypothesized that mixed-phase clouds are maintained through a balance between liquid water condensation resulting from the cloud-top radiative cooling and ice removal by precipitation (Pinto 1998; Harrington et al. 1999). In their modeling study Harrington et al. (1999) found that the maintenance of this balance depends strongly on the ambient concentration of ice forming nucleus (IFN). In a follow-up study, Jiang et al. (2002), using only 30% of IFN concentration predicted by Meyers et al. (1992) IFN parameterization were able to obtain results similar to the observations reported by Pinto (1998). The IFN concentration measurements collected during the Mixed-Phase Arctic Cloud Experiment (M-PACE), conducted in October 2004 over the North Slope of Alaska and the Beaufort Sea (Verlinde et al. 2005), also showed much lower values then those predicted (Prenne, pers. comm.) by currently accepted ice nucleation parameterizations (e.g. Meyers et al. 1992). The goal of this study is to use the extensive IFN data taken during M-PACE to examine what effects low IFN concentrations have on mesoscale cloud structure and coastal dynamics.
Avramov, A.; Harringston, J.Y.; Verlinde, J.
, radar-based retrieval methods. On average, mixed-phase cloud ice particle mean diameters increase fromTOWARDS A CHARACTERIZATION OF ARCTIC MIXED-PHASE CLOUDS Shupe, M. CIRES/NOAA/ETL Kollias, P Laboratory P.O. Box, Upton, NY www.bnl.gov ABSTRACT Mixed-phase clouds play a unique role in the Arctic
Final Technical Report for "Ice nuclei relation to aerosol properties: Data analysis and model parameterization for IN in mixed-phase clouds"�? (DOE/SC00002354)
Clouds play an important role in weather and climate. In addition to their key role in the hydrologic cycle, clouds scatter incoming solar radiation and trap infrared radiation from the surface and lower atmosphere. Despite their importance, feedbacks involving clouds remain as one of the largest sources of uncertainty in climate models. To better simulate cloud processes requires better characterization of cloud microphysical processes, which can affect the spatial extent, optical depth and lifetime of clouds. To this end, we developed a new parameterization to be used in numerical models that describes the variation of ice nuclei (IN) number concentrations active to form ice crystals in mixed-phase (water droplets and ice crystals co-existing) cloud conditions as these depend on existing aerosol properties and temperature. The parameterization is based on data collected using the Colorado State University continuous flow diffusion chamber in aircraft and ground-based campaigns over a 14-year period, including data from the DOE-supported Mixed-Phase Arctic Cloud Experiment. The resulting relationship is shown to more accurately represent the variability of ice nuclei distributions in the atmosphere compared to currently used parameterizations based on temperature alone. When implemented in one global climate model, the new parameterization predicted more realistic annually averaged cloud water and ice distributions, and cloud radiative properties, especially for sensitive higher latitude mixed-phase cloud regions. As a test of the new global IN scheme, it was compared to independent data collected during the 2008 DOE-sponsored Indirect and Semi-Direct Aerosol Campaign (ISDAC). Good agreement with this new data set suggests the broad applicability of the new scheme for describing general (non-chemically specific) aerosol influences on IN number concentrations feeding mixed-phase Arctic stratus clouds. Finally, the parameterization was implemented into a regional cloud-resolving model to compare predictions of ice crystal concentrations and other cloud properties to those observed in two intensive case studies of Arctic stratus during ISDAC. Our implementation included development of a prognostic scheme of ice activation using the IN parameterization so that the most realistic treatment of ice nuclei, including their budget (gains and losses), was achieved. Many cloud microphysical properties and cloud persistence were faithfully reproduced, despite a tendency to under-predict (by a few to several times) ice crystal number concentrations and cloud ice mass, in agreement with some other studies. This work serves generally as the basis for improving predictive schemes for cloud ice crystal activation in cloud and climate models, and more specifically as the basis for such a scheme to be used in a Multi-scale Modeling Format (MMF) that utilizes a connected system of cloud-resolving models on a global grid in an effort to better resolve cloud processes and their influence on climate.
Paul J. DeMott, Anthony J. Prenni; Sonia M. Kreidenweis
Simulations of Arctic Mixed-Phase Clouds in Forecasts with CAM3 and AM2 for M-PACE
Simulations of mixed-phase clouds in short-range forecasts with the National Center for Atmospheric Research Community Atmosphere Model version 3 (CAM3) and the Geophysical Fluid Dynamics Laboratory (GFDL) climate model (AM2) for the Mixed-Phase Arctic Cloud Experiment (M-PACE) are performed under the DOE CCPP-ARM Parameterization Testbed (CAPT), which initializes the climate models with analysis data produced from numerical weather prediction (NWP) centers. It is shown that CAM3 significantly underestimates the observed boundary layer mixed-phase clouds and cannot realistically simulate the variations with temperature and cloud height of liquid water fraction in the total cloud condensate based an oversimplified cloud microphysical scheme. In contrast, AM2 reasonably reproduces the observed boundary layer clouds while its clouds contain much less cloud condensate than CAM3 and the observations. Both models underestimate the observed cloud top and base for the boundary layer clouds. The simulation of the boundary layer mixed-phase clouds and their microphysical properties is considerably improved in CAM3 when a new physically based cloud microphysical scheme is used. The new scheme also leads to an improved simulation of the surface and top of the atmosphere longwave radiative fluxes in CAM3. It is shown that the Bergeron-Findeisen process, i.e., the ice crystal growth by vapor deposition at the expense of coexisting liquid water, is important for the models to correctly simulate the characteristics of the observed microphysical properties in mixed-phase clouds. Sensitivity tests show that these results are not sensitive to the analysis data used for model initializations. Increasing model horizontal resolution helps capture the subgrid-scale features in Arctic frontal clouds but does not help improve the simulation of the single-layer boundary layer clouds. Ice crystal number density has large impact on the model simulated mixed-phase clouds and their microphysical properties and needs to be accurately represented in climate models.
Xie, Shaocheng; Boyle, James; Klein, Stephen A.; Liu, Xiaohong; Ghan, Steven J.
Intercomparison of model simulations of mixed-phase clouds observed during the ARM Mixed-Phase Arctic Cloud Experiment. Part II: Multi-layered cloud
Results are presented from an intercomparison of single-column and cloud-resolving model simulations of a deep, multi-layered, mixed-phase cloud system observed during the ARM Mixed-Phase Arctic Cloud Experiment. This cloud system was associated with strong surface turbulent sensible and latent heat fluxes as cold air flowed over the open Arctic Ocean, combined with a low pressure system that supplied moisture at mid-level. The simulations, performed by 13 single-column and 4 cloud-resolving models, generally overestimate the liquid water path and strongly underestimate the ice water path, although there is a large spread among the models. This finding is in contrast with results for the single-layer, low-level mixed-phase stratocumulus case in Part I of this study, as well as previous studies of shallow mixed-phase Arctic clouds, that showed an underprediction of liquid water path. The overestimate of liquid water path and underestimate of ice water path occur primarily when deeper mixed-phase clouds extending into the mid-troposphere were observed. These results suggest important differences in the ability of models to simulate Arctic mixed-phase clouds that are deep and multi-layered versus shallow and single-layered. In general, models with a more sophisticated, two-moment treatment of the cloud microphysics produce a somewhat smaller liquid water path that is closer to observations. The cloud-resolving models tend to produce a larger cloud fraction than the single-column models. The liquid water path and especially the cloud fraction have a large impact on the cloud radiative forcing at the surface, which is dominated by the longwave flux for this case.
Morrison, H; McCoy, R B; Klein, S A; Xie, S; Luo, Y; Avramov, A; Chen, M; Cole, J; Falk, M; Foster, M; Genio, A D; Harrington, J; Hoose, C; Khairoutdinov, M; Larson, V; Liu, X; McFarquhar, G; Poellot, M; Shipway, B; Shupe, M; Sud, Y; Turner, D; Veron, D; Walker, G; Wang, Z; Wolf, A; Xu, K; Yang, F; Zhang, G
Retrieval of Cloud Phase Using the Moderate Resolution Imaging Spectroradiometer Data during the Mixed-Phase Arctic Cloud Experiment
Improving climate model predictions over Earth's polar regions requires a comprehensive knowledge of polar cloud microphysics. Over the Arctic, there is minimal contrast between the clouds and background snow surface, making it difficult to detect clouds and retrieve their phase from space. Snow and ice cover, temperature inversions, and the predominance of mixed-phase clouds make it even more difficult to determine cloud phase. Also, since determining cloud phase is the first step toward analyzing cloud optical depth, particle size, and water content, it is vital that the phase be correct in order to obtain accurate microphysical and bulk properties. Changes in these cloud properties will, in turn, affect the Arctic climate since clouds are expected to play a critical role in the sea ice albedo feedback. In this paper, the IR trispectral technique (IRTST) is used as a starting point for a WV and 11-{micro}m brightness temperature (T11) parameterization (WVT11P) of cloud phase using MODIS data. In addition to its ability to detect mixed-phase clouds, the WVT11P also has the capability to identify thin cirrus clouds overlying mixed or liquid phase clouds (multiphase ice). Results from the Atmospheric Radiation Measurement (ARM) MODIS phase model (AMPHM) are compared to the surface-based cloud phase retrievals over the ARM North Slope of Alaska (NSA) Barrow site and to in-situ data taken from University of North Dakota Citation (CIT) aircraft which flew during the Mixed-Phase Arctic Cloud Experiment (MPACE). It will be shown that the IRTST and WVT11P combined to form the AMPHM can achieve a relative high accuracy of phase discrimination compared to the surface-based retrievals. Since it only uses MODIS WV and IR channels, the AMPHM is robust in the sense that it can be applied to daytime, twilight, and nighttime scenes with no discontinuities in the output phase.
Spangenberg, D.; Minnis, P.; Shupe, M.; Uttal, T.; Poellot, M.
Influence of parameterized ice habit on simulated mixed phase Arctic clouds
Influence of parameterized ice habit on simulated mixed phase Arctic clouds Alexander Avramov1 12 February 2010. [1] The phase partitioning of cloud mass between liquid and ice in mixed phase clouds and its dependence on ambient ice nuclei (IN) concentrations and ice habit parameterizations
A Numerical Sensitivity Study of Aerosol Influence on Immersion Freezing in Mixed-Phase Stratiform Clouds
freezing in a mixed-phase stratiform cloud. Immersion freez- ing is represented using a parameterization, and the larger droplets nucleate into ice particles through the immersion freezing process. In mixed-phaseA Numerical Sensitivity Study of Aerosol Influence on Immersion Freezing in Mixed-Phase Stratiform
Eloranta, Edwin W.
Effects of ice number concentration on dynamics of a shallow mixed-phase stratiform cloud
Previous modeling studies have shown a high sensitivity of simulated properties of mixed-phase clouds to ice number concentration, Ni, with many models losing their ability to maintain the liquid phase as Ni increases. Although models differ widely at what Ni the mixed-phase cloud becomes unstable, the transition from a mixed-phase to an ice only cloud in many cases occurs over a narrow range of ice concentration. To gain better understanding of this non-linear model behavior, in this study, we analyze simulations of a mixed-phase stratiform Artic cloud observed on 26 April 2008 during recent Indirect and Semi-Direct Aerosol Campaign (ISDAC). The BASE simulation, in which Ni is constrained to match the measured value, produces a long-lived cloud in a quasi steady state similar to that observed. The simulation without the ice (NO_ICE) produces a comparable but slightly thicker cloud because more moisture is kept in the mixed layer due to lack of precipitation. When Ni is quadrupled relative to BASE (HI_ICE), the cloud starts loosing liquid water almost immediately and the liquid water path is reduced by half in less than two hours. The changes in liquid water are accompanied by corresponding reduction in the radiative cooling of the layer and a slow down in the vertical mixing, confirming the important role of interactions among microphysics, radiation and dynamics in this type of clouds. Deviations of BASE and HI_ICE from NO_ICE are used to explore the linearity of the model response to variation in Ni. It is shown that at early stages, changes in liquid and ice water as well as in radiative cooling/heating rates are proportional to the Ni change, while changes in the vertical buoyancy flux are qualitatively different in HI_ICE compared to BASE. Thus, while the positive feedback between the liquid water path and radiative cooling of the cloud layer is essential for glaciation of the cloud at higher Ni, the non-linear (with respect to Ni) reduction in positive buoyancy flux within and below the liquid cloud layer emerges as the process that influences the initial response of the mixed layer dynamics to the appearance of ice and subsequently determines the sustainability of liquid water in the cloud in this case.
Ovchinnikov, Mikhail; Korolev, Alexei; Fan, Jiwen
Statistical Analysis of Aerosol Effects on Simulated Mixed-Phase Clouds and Precipitation in the Alps
Increasing the aerosol number in warm-phase clouds is thought to decrease the rain formation rate, whereas the physical processes taking place in mixed-phase clouds are more uncertain. Increasing number concentrations of soluble aerosols may ...
Elias M. Zubler; Ulrike Lohmann; Daniel L�thi; Christoph Sch�r; Andreas Muhlbauer
Studying Mixed-Phased Clouds Using Ground-Based Active and Passive...
when >0C and only ice crystals when < -40C, between 0 and -40C, clouds can be of ice, water, or mixed-phase composition (Rauber and Tokay 1991; Cober et al. 2001). Cloud...
Results are presented from an intercomparison of single-column and cloud-resolving model simulations of a cold-air outbreak mixed-phase stratocumulus cloud observed during the Atmospheric Radiation Measurement (ARM) program's Mixed-Phase Arctic Cloud Experiment. The observed cloud occurred in a well-mixed boundary layer with a cloud top temperature of -15 C. The observed liquid water path of around 160 g m{sup -2} was about two-thirds of the adiabatic value and much greater than the mass of ice crystal precipitation which when integrated from the surface to cloud top was around 15 g m{sup -2}. The simulations were performed by seventeen single-column models (SCMs) and nine cloud-resolving models (CRMs). While the simulated ice water path is generally consistent with the observed values, the median SCM and CRM liquid water path is a factor of three smaller than observed. Results from a sensitivity study in which models removed ice microphysics indicate that in many models the interaction between liquid and ice-phase microphysics is responsible for the large model underestimate of liquid water path. Despite this general underestimate, the simulated liquid and ice water paths of several models are consistent with the observed values. Furthermore, there is some evidence that models with more sophisticated microphysics simulate liquid and ice water paths that are in better agreement with the observed values, although considerable scatter is also present. Although no single factor guarantees a good simulation, these results emphasize the need for improvement in the model representation of mixed-phase microphysics. This case study, which has been well observed from both aircraft and ground-based remote sensors, could be a benchmark for model simulations of mixed-phase clouds.
Klein, S A; McCoy, R B; Morrison, H; Ackerman, A; Avramov, A; deBoer, G; Chen, M; Cole, J; DelGenio, A; Golaz, J; Hashino, T; Harrington, J; Hoose, C; Khairoutdinov, M; Larson, V; Liu, X; Luo, Y; McFarquhar, G; Menon, S; Neggers, R; Park, S; Poellot, M; von Salzen, K; Schmidt, J; Sednev, I; Shipway, B; Shupe, M; Spangenberg, D; Sud, Y; Turner, D; Veron, D; Falk, M; Foster, M; Fridlind, A; Walker, G; Wang, Z; Wolf, A; Xie, S; Xu, K; Yang, F; Zhang, G
An Analytic Scaling Law for the Depositional Growth of Snow in Thin Mixed-Phase Layer Clouds
In various practical problems, such as assessing the threat of aircraft icing or calculating radiative transfer, it is important to know whether mixed-phase clouds contain significant liquid water content. Some mixed-phase clouds remain ...
Vincent E. Larson; Adam J. Smith
LES Simulations of Roll Clouds Observed During Mixed- Phase Arctic Cloud Experiment
Roll clouds, and associated roll convection, are fairly common features of the atmospheric boundary layer. While these organized cumuliform clouds are found over many regions of the planet, they are quite ubiquitous near the edge of the polar ice sheets. In particular, during periods of off-ice flow, when cold polar air flows from the ice pack over the relatively warm ocean water, strong boundary layer convection develops along with frequent rolls. According to Bruemmer and Pohlman (2000), most of the total cloud cover in the Arctic is due to roll clouds. In an effort to examine the influences of mixed-phase microphysics on the boundary layer evolution of roll clouds during off-ice flow, Olsson and Harrington (2000) used a 2D mesoscale model coupled to a bulk microphysical scheme (see Section 2). Their results showed that mixed-phase clouds produced more shallow boundary layers with weaker turbulence than liquid-phase cases. Furthermore, their results showed that because of th e reduced turbulent drag on the atmosphere in the mixed-phase case, regions of mesoscale divergence in the marginal ice-zone were significantly affected. A follow-up 2D study (Harrington and Olsson 2001) showed that the reduced turbulent intensity in mixed-phase cases was due to precipitation. Ice precipitation caused downdraft stabilization which fed back and caused a reduction in the surface heat fluxes. In this work, we extend the work of Olsson and Harrington (2000) and Harrington and Olsson (2001) by examining the impacts of ice microphysics on roll convection. We will present results that illustrate how microphysics alters roll cloud structure and dynamics.
Greenberg, S.D.; Harrington, J.Y.; Prenni, A.; DeMott, P.
Evaluation of a New Mixed-Phase Cloud Microphysics Parameterization with CAM3 Single-Column Model and M-PACE Observations
Most global climate models generally prescribe the partitioning of condensed water into liquid droplets and ice crystals in mixed-phase clouds according to a temperature-dependent function, which affects modeled cloud phase, cloud lifetime and radiative properties. This study evaluates a new mixed-phase cloud microphysics parameterization (for ice nucleation and water vapor deposition) against the Atmospheric Radiation Measurement (ARM) Mixed-phase Arctic Cloud Experiment (M-PACE) observations using the NCAR Community Atmospheric Model Version 3 (CAM3) single column model (SCAM). It is shown that SCAM with the new scheme produces a more realistic simulation of the cloud phase structure and the partitioning of condensed waterinto liquid droplets against observations during the M-PACE than the standard CAM. Sensitivity test indicates that ice number concentration could play an important role in the simulated mixed-phase cloud microphysics, and thereby needs to be realistically represented in global climate models.
Liu, Xiaohong; Xie, Shaocheng; Ghan, Steven J.
Radiative Influences on Glaciation Time-Scales of Mixed-Phase Clouds
Radiative Influences on Glaciation Time-Scales of Mixed-Phase Clouds Radiative Influences on Glaciation Time-Scales of Mixed-Phase Clouds Harrington, Jerry The Pennsylvania State University Category: Modeling Mixed-phase stratus clouds are dominant in the Arctic during much of the year. These clouds typically have liquid tops that precipitate ice. Time scales for the complete glaciation of such clouds (the Bergeron process) are typically computed using the classical mass growth equations for crystals and liquid drops. However, mixed phase arctic stratus have significant infrared cooling and solar heating (during the warm season) rates that can affect the growth of water drops and ice crystals, and therefore the strength of the Bergeron process. To examine the influence of radiative heating and cooling on the Bergeron process, we incorporate a
Results are presented from an intercomparison of single-column and cloud-resolving model simulations of a cold-air outbreak mixed-phase stratocumulus cloud observed during the Atmospheric Radiation Measurement (ARM) program's Mixed-Phase Arctic Cloud Experiment. The observed cloud occurred in a well-mixed boundary layer with a cloud top temperature of -15 C. The observed average liquid water path of around 160 g m{sup -2} was about two-thirds of the adiabatic value and much greater than the average mass of ice crystal precipitation which when integrated from the surface to cloud top was around 15 g m{sup -2}. The simulations were performed by seventeen single-column models (SCMs) and nine cloud-resolving models (CRMs). While the simulated ice water path is generally consistent with the observed values, the median SCM and CRM liquid water path is a factor of three smaller than observed. Results from a sensitivity study in which models removed ice microphysics suggest that in many models the interaction between liquid and ice-phase microphysics is responsible for the large model underestimate of liquid water path. Despite this general underestimate, the simulated liquid and ice water paths of several models are consistent with the observed values. Furthermore, there is evidence that models with more sophisticated microphysics simulate liquid and ice water paths that are in better agreement with the observed values, although considerable scatter is also present. Although no single factor guarantees a good simulation, these results emphasize the need for improvement in the model representation of mixed-phase microphysics.
Klein, Stephen A.; McCoy, Renata B.; Morrison, Hugh; Ackerman, Andrew S.; Avramov, Alexander; de Boer, Gijs; Chen, Mingxuan; Cole, Jason N.S.; Del Genio, Anthony D.; Falk, Michael; Foster, Michael J.; Fridlind, Ann; Golaz, Jean-Christophe; Hashino, Tempei; Harrington, Jerry Y.; Hoose, Corinna; Khairoutdinov, Marat F.; Larson, Vincent E.; Liu, Xiaohong; Luo, Yali; McFarquhar, Greg M.; Menon, Surabi; Neggers, Roel A. J.; Park, Sungsu; Poellot, Michael R.; Schmidt, Jerome M.; Sednev, Igor; Shipway, Ben J.; Shupe, Matthew D.; Spangenberg, Douglas A.; Sud, Yogesh C.; Turner, David D.; Veron, Dana E.; von Salzen, Knut; Walker, Gregory K.; Wang, Zhien; Wolf, Audrey B.; Xie, Shaocheng; Xu, Kuan-Man; Yang, Fanglin; Zhang, Gong
Representation of Arctic Mixed-Phase clouds and the Wegener-Bergeron-Findeisen Process in Climate Models: Perspectives from a Cloud-Resolving Study
Two types of Arctic mixed-phase clouds observed during the ISDAC and M-PACE field campaigns are simulated using a 3-dimensional cloud-resolving model (CRM) with size-resolved cloud microphysics. The modeled cloud properties agree reasonably well with aircraft measurements and surface-based retrievals. Cloud properties such as the probability density function (PDF) of vertical velocity (w), cloud liquid and ice, the regime of ice growth at the expense of liquid water (i.e., Wegener-Bergeron-Findeisen (WBF) process), and the inherent relationships among cloud properties/processes in the mixed-phase layers are examined to gain insights for improving the representation of the mixed-phase processes in General Circulation Models (GCMs). We find that, the WBF process only occurs in about 50% of the mixed-phase regime with the vast majority occurring in the downdrafts. In updrafts both liquid and ice grow simultaneously. But in GCMs, it is not necessary to treat the WBF process at the subgrid scale. Our CRM results produce a w distribution well represented by a Gaussian normal function, validating, at least for arctic clouds, the subgrid treatment used in GCMs. Our CRM results also support the assumption frequently used in GCMs that mixed phase clouds maintain water vapor very near liquid saturation. A Gamma function with a fixed variance does not accurately represent the subgrid variability of cloud liquid. The PDFs of cloud liquid and cloud ice can be fitted with Gamma functions, and a normal function can be used for total water, but the variance should not be fixed. The relationship between the ice depositional growth rate and cloud ice strongly depends on the capacitance of ice particles. The assumption for the capacitance of ice particles (e.g., 1.0 for spheres) used in GCMs could lead to a large deviation in ice depositional growth. At large sales, the maximum overlap assumption looks appropriate.
Fan, Jiwen; Ghan, Steven J.; Ovchinnikov, Mikhail; Liu, Xiaohong; Rasch, Philip J.; Korolev, Alexei
Intercomparison of Bulk Cloud Microphysics Schemes in Mesoscale Simulations of Springtime Arctic Mixed-Phase Stratiform Clouds
A persistent, weakly forced, horizontally extensive mixed-phase boundary layer cloud observed on 4�5 May 1998 during the Surface Heat Budget of the Arctic Ocean (SHEBA)/First International Satellite Cloud Climatology Project (ISCCP) Regional ...
H. Morrison; J. O. Pinto
In Situ Aircraft Measurements of the Vertical Distribution of Liquid and Ice Water Content in Midlatitude Mixed-Phase Clouds
The vertical distribution of liquid and ice water content and their partitioning is studied using 34 cases of in situ measured microphysical properties in midlatitude mixed-phase clouds, with liquid water path ranging from near zero to ~248 g m?2, ...
Yoo-Jeong Noh; Curtis J. Seaman; Thomas H. Vonder Haar; Guosheng Liu
Effects of Aerosol Solubility and Regeneration on Mixed-Phase Orographic Clouds and Precipitation
A detailed bin aerosol-microphysics scheme has been implemented into the Weather Research and Forecast Model to investigate the effects of aerosol solubility and regeneration on mixed-phase orographic clouds and precipitation. Two-dimensional ...
Lulin Xue; Amit Teller; Roy Rasmussen; Istvan Geresdi; Zaitao Pan; Xiaodong Liu
Improvements of a Mixed-Phase Cloud Scheme Using Aircraft Observations
To improve the quality of forecasts of mixed-phase clouds in winter storms, some aspects of a cloud scheme are examined in detail. Modifications to the basic formalism and specification of selected parameters of the cloud model are studied, and ...
Andr� Tremblay; Paul A. Vaillancourt; Stewart G. Cober; Anna Glazer; George A. Isaac
Evaluation of Mixed-Phase Cloud Microphysics Parameterizations with the NCAR Single Column Climate Model (SCAM) and ARM Observations
Mixed-phase stratus clouds are ubiquitous in the Arctic and play an important role in climate in this region. However, climate models have generally proven unsuccessful at simulating the partitioning of condensed water into liquid droplets and ice crystals in these Arctic clouds, which affect modeled cloud phase, cloud lifetime and radiative properties. An ice nucleation parameterization and a vapor deposition scheme were developed that together provide a physically-consistent treatment of mixed-phase clouds in global climate models. These schemes have been implemented in the National Center for Atmospheric Research (NCAR) Community Atmospheric Model Version 3 (CAM3). This report documents the performance of these schemes against ARM Mixed-phase Arctic Cloud Experiment (M-PACE) observations using the CAM single column model version (SCAM). SCAM with our new schemes has a more realistic simulation of the cloud phase structure and the partitioning of condensed water into liquid droplets against observations during the M-PACE than the standard CAM simulations.
Liu, X; Ghan, SJ; Xie, S
Ice Formation in Arctic Mixed-Phase Clouds: Insights from a 3-D Cloud-Resolving Model with Size-Resolved Aerosol and Cloud Microphysics
The single-layer mixed-phase clouds observed during the Atmospheric Radiation Measurement (ARM) program�s Mixed-Phase Arctic Cloud Experiment (MPACE) are simulated with a 3-dimensional cloud-resolving model the System for Atmospheric Modeling (SAM) coupled with an explicit bin microphysics scheme and a radar-lidar simulator. Two possible ice enhancement mechanisms � activation of droplet evaporation residues by condensation-followed-by-freezing and droplet freezing by contact freezing inside-out, are scrutinized by extensive comparisons with aircraft and radar and lidar measurements. The locations of ice initiation associated with each mechanism and the role of ice nuclei (IN) in the evolution of mixed-phase clouds are mainly addressed. Simulations with either mechanism agree well with the in-situ and remote sensing measurements on ice microphysical properties but liquid water content is slightly underpredicted. These two mechanisms give very similar cloud microphysical, macrophysical, dynamical, and radiative properties, although the ice nucleation properties (rate, frequency and location) are completely different. Ice nucleation from activation of evaporation nuclei is most efficient near cloud top areas concentrated on the edges of updrafts, while ice initiation from the drop freezing process has no significant location preference (occurs anywhere that droplet evaporation is significant). Both enhanced nucleation mechanisms contribute dramatically to ice formation with ice particle concentration of 10-15 times higher relative to the simulation without either of them. The contribution of ice nuclei (IN) recycling from ice particle evaporation to IN and ice particle concentration is found to be very significant in this case. Cloud can be very sensitive to IN initially and form a nonquilibrium transition condition, but become much less sensitive as cloud evolves to a steady mixed-phase condition. The parameterization of Meyers et al. [1992] with the observed MPACE IN concentration is able to predict the observed mixed-phase clouds reasonably well. This validation may facilitate the application of this parameterization in the cloud and climate models to simulate Arctic clouds.
Fan, Jiwen; Ovtchinnikov, Mikhail; Comstock, Jennifer M.; McFarlane, Sally A.; Khain, Alexander
Simulating mixed-phase Arctic stratus clouds: Sensitivity to ice initiationmechanisms
The importance of Arctic mixed-phase clouds on radiation and the Arctic climate is well known. However, the development of mixed-phase cloud parameterization for use in large scale models is limited by lack of both related observations and numerical studies using multidimensional models with advanced microphysics that provide the basis for understanding the relative importance of different microphysical processes that take place in mixed-phase clouds. To improve the representation of mixed-phase cloud processes in the GISS GCM we use the GISS single-column model coupled to a bin resolved microphysics (BRM) scheme that was specially designed to simulate mixed-phase clouds and aerosol-cloud interactions. Using this model with the microphysical measurements obtained from the DOE ARM Mixed-Phase Arctic Cloud Experiment (MPACE) campaign in October 2004 at the North Slope of Alaska, we investigate the effect of ice initiation processes and Bergeron-Findeisen process (BFP) on glaciation time and longevity of single-layer stratiform mixed-phase clouds. We focus on observations taken during October 9th-10th, which indicated the presence of a single-layer mixed-phase clouds. We performed several sets of 12-hour simulations to examine model sensitivity to different ice initiation mechanisms and evaluate model output (hydrometeors concentrations, contents, effective radii, precipitation fluxes, and radar reflectivity) against measurements from the MPACE Intensive Observing Period. Overall, the model qualitatively simulates ice crystal concentration and hydrometeors content, but it fails to predict quantitatively the effective radii of ice particles and their vertical profiles. In particular, the ice effective radii are overestimated by at least 50%. However, using the same definition as used for observations, the effective radii simulated and that observed were more comparable. We find that for the single-layer stratiform mixed-phase clouds simulated, process of ice phase initiation due to freezing of supercooled water in both saturated and subsaturated (w.r.t. water) environments is as important as primary ice crystal origination from water vapor. We also find that the BFP is a process mainly responsible for the rates of glaciation of simulated clouds. These glaciation rates cannot be adequately represented by a water-ice saturation adjustment scheme that only depends on temperature and liquid and solid hydrometeors contents as is widely used in bulk microphysics schemes and are better represented by processes that also account for supersaturation changes as the hydrometeors grow.
Sednev, I.; Menon, S.; McFarquhar, G.
Simulating mixed-phase Arctic stratus clouds: sensitivity to ice initiation mechanisms
The importance of Arctic mixed-phase clouds on radiation and the Arctic climate is well known. However, the development of mixed-phase cloud parameterization for use in large scale models is limited by lack of both related observations and numerical studies using multidimensional models with advanced microphysics that provide the basis for understanding the relative importance of different microphysical processes that take place in mixed-phase clouds. To improve the representation of mixed-phase cloud processes in the GISS GCM we use the GISS single-column model coupled to a bin resolved microphysics (BRM) scheme that was specially designed to simulate mixed-phase clouds and aerosol-cloud interactions. Using this model with the microphysical measurements obtained from the DOE ARM Mixed-Phase Arctic Cloud Experiment (MPACE) campaign in October 2004 at the North Slope of Alaska, we investigate the effect of ice initiation processes and Bergeron-Findeisen process (BFP) on glaciation time and longevity of single-layer stratiform mixed-phase clouds. We focus on observations taken during 9th-10th October, which indicated the presence of a single-layer mixed-phase clouds. We performed several sets of 12-h simulations to examine model sensitivity to different ice initiation mechanisms and evaluate model output (hydrometeors concentrations, contents, effective radii, precipitation fluxes, and radar reflectivity) against measurements from the MPACE Intensive Observing Period. Overall, the model qualitatively simulates ice crystal concentration and hydrometeors content, but it fails to predict quantitatively the effective radii of ice particles and their vertical profiles. In particular, the ice effective radii are overestimated by at least 50%. However, using the same definition as used for observations, the effective radii simulated and that observed were more comparable. We find that for the single-layer stratiform mixed-phase clouds simulated, process of ice phase initiation due to freezing of supercooled water in both saturated and undersaturated (w.r.t. water) environments is as important as primary ice crystal origination from water vapor. We also find that the BFP is a process mainly responsible for the rates of glaciation of simulated clouds. These glaciation rates cannot be adequately represented by a water-ice saturation adjustment scheme that only depends on temperature and liquid and solid hydrometeors contents as is widely used in bulk microphysics schemes and are better represented by processes that also account for supersaturation changes as the hydrometeors grow.
Sednev, Igor; Sednev, I.; Menon, S.; McFarquhar, G.
Radiative Processes in Upper Tropospheric Mixed-Phase Clouds
The diffusional mass evolution of hydrometeors in upper tropospheric clouds for various radiative conditions in the cloud and for varying ambient moisture Supply is simulated using a time dependent microphysical model. Radiation can play an ...
Douglas A. Wesley; Stephen K. Cox
Observed Microphysical Structure ofObserved Microphysical Structure of MidMid--Level, MixedLevel, Mixed--Phase CloudsPhase Clouds
Level, Mixed--Phase CloudsPhase Clouds DOD Center for Geosciences/ Atmospheric Research Colorado State understood, but they cover ~ 22% of globe. Mixed-Phase Structure of Clouds Unknown. 30% are mixed-phase --- i.e. contain both ice and liquid. We need to know ice structure for weather and climate forecasts, e
Evaluation of Mixed-Phase Cloud Parameterizations in Short-Range Weather Forecasts with CAM3 and AM2 for Mixed-Phase Arctic Cloud Experiment
By making use of the in-situ data collected from the recent Atmospheric Radiation Measurement Mixed-Phase Arctic Cloud Experiment, we have tested the mixed-phase cloud parameterizations used in the two major U.S. climate models, the National Center for Atmospheric Research Community Atmosphere Model version 3 (CAM3) and the Geophysical Fluid Dynamics Laboratory climate model (AM2), under both the single-column modeling framework and the U.S. Department of Energy Climate Change Prediction Program-Atmospheric Radiation Measurement Parameterization Testbed. An improved and more physically based cloud microphysical scheme for CAM3 has been also tested. The single-column modeling tests were summarized in the second quarter 2007 Atmospheric Radiation Measurement metric report. In the current report, we document the performance of these microphysical schemes in short-range weather forecasts using the Climate Chagne Prediction Program Atmospheric Radiation Measurement Parameterizaiton Testbest strategy, in which we initialize CAM3 and AM2 with realistic atmospheric states from numerical weather prediction analyses for the period when Mixed-Phase Arctic Cloud Experiment was conducted.
Xie, S; Boyle, J; Klein, S; Liu, X; Ghan, S
Simulating Arctic mixed-phase clouds: Sensitivity to environmental...
as well as aggregates to precipitation fluxes and radar reflectivity. Observations of icewater drop size distributions, cloud phase, etc., allow us to constrain model...
Observed Microphysical Structure of Midlevel, Mixed-Phase Clouds
This paper analyzes airborne measurements of six midlevel clouds observed over the Great Plains of the United States in late 1999 and early 2000 during the fifth of the Complex Layered-Cloud Experiments (CLEX-5). Data show that these innocuous-...
Robert P. Fleishauer; Vincent E. Larson; Thomas H. Vonder Haar
Relative Humidity in Liquid, Mixed-Phase, and Ice Clouds
The results of in situ observations of the relative humidity in liquid, mixed, and ice clouds typically stratiform in nature and associated with mesoscale frontal systems at temperatures ?45�C < Ta < ?5�C are presented. The data were collected ...
Alexei Korolev; George A. Isaac
Arctic Mixed-Phase Clouds Simulated by a Cloud-Resolving Model: Comparison with ARM Observations and Sensitivity to Microphysics Parameterizations
Single-layer mixed-phase stratiform (MPS) Arctic clouds, which formed under conditions of large surface heat flux combined with general subsidence during a subperiod of the Atmospheric Radiation Measurement (ARM) Program�s Mixed-Phase Arctic ...
Yali Luo; Kuan-Man Xu; Hugh Morrison; Greg McFarquhar
Aerosol Influence on Mixed-Phase Clouds in CAM-Oslo
A new treatment of mixed-phase cloud microphysics has been implemented in the general circulation model, Community Atmosphere Model (CAM)-Oslo, which combines the NCAR CAM2.0.1 and a detailed aerosol module. The new treatment takes into account ...
Trude Storelvmo; J�n Egill Kristj�nsson; Ulrike Lohmann
DOE/SC-ARM-P-07-006 Evaluation of Mixed-Phase Cloud Microphysics
6 6 Evaluation of Mixed-Phase Cloud Microphysics Parameterizations with the NCAR Single Column Climate Model (SCAM) and ARM Observations Second Quarter 2007 ARM Metric Report April 2007 Xiaohong Liu and Steven J. Ghan Pacific Northwest National Laboratory Richland, Washington Shaocheng Xie Lawrence Livermore National Laboratory Livermore, California Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research X. Lui, S.J. Ghan, and S. Xie, DOE/SC-ARM/P-07-006 Summary Mixed-phase stratus clouds are ubiquitous in the Arctic and play an important role in climate in this region. However, climate models have generally proven unsuccessful at simulating the partitioning of condensed water
Sensitivity Studies of Aerosol�Cloud Interactions in Mixed-Phase Orographic Precipitation
Anthropogenic aerosols serve as a source of both cloud condensation nuclei (CCN) and ice nuclei (IN) and affect microphysical properties of clouds. Increasing aerosol number concentration is assumed to retard the cloud droplet coalescence and the ...
Andreas Muhlbauer; Ulrike Lohmann
Mesoscale Modeling of Springtime Arctic Mixed-Phase Stratiform Clouds Using a New Two-Moment Bulk Microphysics Scheme
A new two-moment bulk microphysics scheme is implemented into the polar version of the fifth-generation Pennsylvania State University�NCAR Mesoscale Model (MM5) to simulate arctic mixed-phase boundary layer stratiform clouds observed during ...
Sensitivity Studies of the Importance of Dust Ice Nuclei for the Indirect Aerosol Effect on Stratiform Mixed-Phase Clouds
New parameterizations of contact freezing and immersion freezing in stratiform mixed-phase clouds (with temperatures between 0� and ?35�C) for black carbon and mineral dust assumed to be composed of either kaolinite (simulation KAO) or ...
U. Lohmann; K. Diehl
Estimation of Mixed-Phase Cloud Optical Depth and Position Using In Situ Radiation and Cloud Microphysical Measurements Obtained from a Tethered-Balloon Platform
Microphysical and radiative measurements in boundary layer mixed-phase clouds (MPCs), consisting of ice crystals and liquid droplets, have been analyzed. These cloud measurements were collected during a May�June 2008 tethered-balloon campaign in ...
M. Sikand; J. Koskulics; K. Stamnes; B. Hamre; J. J. Stamnes; R. P. Lawson
Intercomparison of cloud model simulations of Arctic mixed-phase boundary layer clouds observed during SHEBA/FIRE-ACE
An intercomparison of six cloud-resolving and large-eddy simulation models is presented. This case study is based on observations of a persistent mixed-phase boundary layer cloud gathered on 7 May, 1998 from the Surface Heat Budget of Arctic Ocean (SHEBA) and First ISCCP Regional Experiment - Arctic Cloud Experiment (FIRE-ACE). Ice nucleation is constrained in the simulations in a way that holds the ice crystal concentration approximately fixed, with two sets of sensitivity runs in addition to the baseline simulations utilizing different specified ice nucleus (IN) concentrations. All of the baseline and sensitivity simulations group into two distinct quasi-steady states associated with either persistent mixed-phase clouds or all-ice clouds after the first few hours of integration, implying the existence of multiple equilibria. These two states are associated with distinctly different microphysical, thermodynamic, and radiative characteristics. Most but not all of the models produce a persistent mixed-phase cloud qualitatively similar to observations using the baseline IN/crystal concentration, while small increases in the IN/crystal concentration generally lead to rapid glaciation and conversion to the all-ice state. Budget analysis indicates that larger ice deposition rates associated with increased IN/crystal concentrations have a limited direct impact on dissipation of liquid in these simulations. However, the impact of increased ice deposition is greatly enhanced by several interaction pathways that lead to an increased surface precipitation flux, weaker cloud top radiative cooling and cloud dynamics, and reduced vertical mixing, promoting rapid glaciation of the mixed-phase cloud for deposition rates in the cloud layer greater than about 1-2x10-5 g kg-1 s-1. These results indicate the critical importance of precipitation-radiative-dynamical interactions in simulating cloud phase, which have been neglected in previous fixed-dynamical parcel studies of the cloud phase parameter space. Large sensitivity to the IN/crystal concentration also suggests the need for improved understanding of ice nucleation and its parameterization in models.
Morrison, H.; Zuidema, Paquita; Ackerman, Andrew; Avramov, Alexander; de Boer, Gijs; Fan, Jiwen; Fridlind, Ann; Hashino, Tempei; Harrington, Jerry Y.; Luo, Yali; Ovchinnikov, Mikhail; Shipway, Ben
Using Doppler spectra to separate hydrometeor populations and analyze ice precipitation in multilayered mixed-phase clouds
Multimodality of cloud radar Doppler spectra is used to partition cloud particle phases and to separate distinct ice populations in the radar sample volume, thereby facilitating analysis of individual ice showers in multilayered mixed-phase clouds. A 35-GHz cloud radar located at Barrow, Alaska, during the Mixed-Phase Arctic Cloud Experiment collected the Doppler spectra. Data from a pair of collocated depolarization lidars confirmed the presence of two liquid cloud layers reported in this study. Surprisingly, both of these cloud layers were embedded in ice precipitation yet maintained their liquid. Our spectral separation of the ice precipitation yielded two distinct ice populations: ice initiated within the two liquid cloud layers and ice precipitation formed in higher cloud layers. Comparisons of ice fall velocity versus radar reflectivity relationships derived for distinct showers reveal that a single relationship might not properly represent the ice showers during this period.
Rambukkange, Mahlon P.; Verlinde, J.; Eloranta, E. W.; Flynn, Connor J.; Clothiaux, Eugene E.
Parameterization of the Extinction Coefficient in Ice and Mixed-Phase Arctic Clouds during the ISDAC Field Campaign
This report documents the history of attempts to directly measure cloud extinction, the current measurement device known as the Cloud Extinction Probe (CEP), specific problems with direct measurement of extinction coefficient, and the attempts made here to address these problems. Extinction coefficient is one of the fundamental microphysical parameters characterizing bulk properties of clouds. Knowledge of extinction coefficient is of crucial importance for radiative transfer calculations in weather prediction and climate models given that Earth's radiation budget (ERB) is modulated much by clouds. In order for a large-scale model to properly account for ERB and perturbations to it, it must ultimately be able to simulate cloud extinction coefficient well. In turn this requires adequate and simultaneous simulation of profiles of cloud water content and particle habit and size. Similarly, remote inference of cloud properties requires assumptions to be made about cloud phase and associated single-scattering properties, of which extinction coefficient is crucial. Hence, extinction coefficient plays an important role in both application and validation of methods for remote inference of cloud properties from data obtained from both satellite and surface sensors (e.g., Barker et al. 2008). While estimation of extinction coefficient within large-scale models is relatively straightforward for pure water droplets, thanks to Mie theory, mixed-phase and ice clouds still present problems. This is because of the myriad forms and sizes that crystals can achieve, each having their own unique extinction properties. For the foreseeable future, large-scale models will have to be content with diagnostic parametrization of crystal size and type. However, before they are able to provide satisfactory values needed for calculation of radiative transfer, they require the intermediate step of assigning single-scattering properties to particles. The most basic of these is extinction coefficient, yet it is rarely measured directly, and therefore verification of parametrizations is difficult. The obvious solution is to be able to measure microphysical properties and extinction at the same time and for the same volume. This is best done by in situ sampling by instruments mounted on either balloon or aircraft. The latter is the usual route and the one employed here. Yet the problem of actually measuring extinction coefficient directly for arbitrarily complicated particles still remains unsolved.
Korolev, A; Shashkov, A; Barker, H
A FIRE-ACE/SHEBA Case Study of Mixed-Phase Arctic Boundary Layer Clouds: Entrainment Rate Limitations on Rapid Primary Ice Nucleation Processes
Observations of long-lived mixed-phase Arctic boundary layer clouds on 7 May 1998 during the First International Satellite Cloud Climatology Project (ISCCP) Regional Experiment (FIRE)�Arctic Cloud Experiment (ACE)/Surface Heat Budget of the Arctic ...
Ann M. Fridlind; Bastiaan van Diedenhoven; Andrew S. Ackerman; Alexander Avramov; Agnieszka Mrowiec; Hugh Morrison; Paquita Zuidema; Matthew D. Shupe
The Sensitivity of Springtime Arctic Mixed-Phase Stratocumulus Clouds to Surface Layer and Cloud-Top Inversion Layer Moisture Sources
In this study a series of idealized large eddy simulations is used to understand the relative impact of cloud top and subcloud layer sources of moisture on the microphysical-radiative-dynamical feedbacks in an Arctic mixed-phase stratocumulus (...
Amy Solomon; Matthew D. Shupe; Ola Persson; Hugh Morrison; Takanobu Yamaguchi; Peter M. Caldwell; Gijs de Boer
A Scheme for Calculation of the Liquid Fraction in Mixed-Phase Stratiform Clouds in Large-Scale Models
A scheme for calculation of the liquid fraction fl in mixed-phase stratiform clouds has been developed for use in large-scale models. An advantage of the scheme, compared to the interpolation in temperature that is typically used, is that it ...
Leon D. Rotstayn; Brian F. Ryan; Jack J. Katzfey
Minimalist Model of Ice Microphysics in Mixed-phase Stratiform Clouds
The question of whether persistent ice crystal precipitation from super cooled layer clouds can be explained by time-dependent, stochastic ice nucleation is explored using an approximate, analytical model, and a large-eddy simulation (LES) cloud model. The updraft velocity in the cloud defines an accumulation zone, where small ice particles cannot fall out until they are large enough, which will increase the residence time of ice particles in the cloud. Ice particles reach a quasi-steady state between growth by vapor deposition and fall speed at cloud base. The analytical model predicts that ice water content (wi) has a 2.5 power law relationship with ice number concentration ni. wi and ni from a LES cloud model with stochastic ice nucleation also confirm the 2.5 power law relationship. The prefactor of the power law is proportional to the ice nucleation rate, and therefore provides a quantitative link to observations of ice microphysical properties.
Yang, F.; Ovchinnikov, Mikhail; Shaw, Raymond A.
Evaluation of A New Mixed-Phase Cloud Microphysics Parameterization with the NCAR Climate Atmospheric Model (CAM3) and ARM Observations Fourth Quarter 2007 ARM Metric Report
Mixed-phase clouds are composed of a mixture of cloud droplets and ice crystals. The cloud microphysics in mixed-phase clouds can significantly impact cloud optical depth, cloud radiative forcing, and cloud coverage. However, the treatment of mixed-phase clouds in most current climate models is crude and the partitioning of condensed water into liquid droplets and ice crystals is prescribed as temperature dependent functions. In our previous 2007 ARM metric reports a new mixed-phase cloud microphysics parameterization (for ice nucleation and water vapor deposition) was documented and implemented in the NCAR Community Atmospheric Model Version 3 (CAM3). The new scheme was tested against the Atmospheric Radiation Measurement (ARM) Mixed-phase Arctic Cloud Experiment (M-PACE) observations using the single column modeling and short-range weather forecast approaches. In this report this new parameterization is further tested with CAM3 in its climate simulations. It is shown that the predicted ice water content from CAM3 with the new parameterization is in better agreement with the ARM measurements at the Southern Great Plain (SGP) site for the mixed-phase clouds.
X Liu; SJ Ghan; S Xie; J Boyle; SA Klein
ARM - Measurement - Cloud phase
property that captures the state o f the hydrometeors within a cloud (liquid, ice, or mixed-phase). This is distinct from cloud type that involves property descriptors...
A Modeling Case Study of Mixed-Phase Clouds over the Southern Ocean and Tasmania
The cloud structure associated with two frontal passages over the Southern Ocean and Tasmania is investigated. The first event, during August 2006, is characterized by large quantities of supercooled liquid water and little ice. The second case, ...
Anthony E. Morrison; Steven T. Siems; Michael J. Manton; Alex Nazarov
AMSU-B Observations of Mixed-Phase Clouds over Land
Measurements from passive microwave satellite instruments such as the Advanced Microwave Sounding Unit B (AMSU-B) are sensitive to both liquid and ice cloud particles. Radiative transfer modeling is exploited to simulate the response of the AMSU-...
M. N. Deeter; J. Vivekanandan
M. : Role of a parameterized ice-phase mi- crophysics in anof contact nucleation in ice phase initiation in clouds, J.simulated, process of ice phase initiation due to freezing
Sednev, I.
A Dual-Wavelength Radar Method for Ice-Water Characterization in Mixed-Phase Clouds
A dual-wavelength method to differentiate supercooled water from ice and to measure mass content in each phase in cold stratiform clouds is proposed and discussed. The differential attenuation Ad, whose direct measurement is available with dual-...
Marielle Gosset; Henri Sauvageot
Black carbon enrichment in atmospheric ice particle residuals observed in lower tropospheric mixed phase clouds
The enrichment of black carbon (BC) in residuals of small ice crystals was investigated during intensive experiments in winter 2004 and 2005 at the high alpine research station Jungfraujoch (3580 m asl, Switzerland). Two inlets were used to sample the bulk aerosol (residuals of cloud droplets and ice crystals as well as non-activated aerosol particles) and the residual particles of small ice crystals (diameter 5 - 20 ?m). An enrichment of the BC mass fraction in the ice particle residuals was observed by investigating the measured BC mass concentration as a fraction of the bulk (submicrometer) aerosol mass concentration sampled by the two inlets. On average, the BC mass fraction was 5% for the bulk aerosol and 27% for the ice particle residuals. The observed enrichment of BC in ice particle residuals suggests that BC containing particles preferentially act as ice nuclei, with important implications for the indirect aerosol effect via glaciation of clouds.
Cozic, J.; Mertes, S.; Verheggen, B.; Cziczo, Daniel J.; Gallavardin, S. J.; Walter, S.; Baltensperger, Urs; Weingartner, E.
Black carbon enrichment in atmospheric ice particle residuals observed in lower trophospheric mixed phase clouds
The enrichment of black carbon (BC) in residuals of small ice particles was investigated during intensive experiments in winter 2004 and 2005 at the high alpine research station Jungfraujoch (3580 m asl, Switzerland). Two inlets were used to sample the bulk aerosol (residuals of cloud droplets and ice crystals as well as non-activated aerosol particles) and the residual particles of small ice crystals (diameter 5 - 20 m). An enrichment of the BC mass fraction in the ice particle residuals was observed by investigating the measured BC mass concentration as a fraction of the bulk (submicrometer) aerosol mass concentration sampled by the two inlets. On average, the BC mass fraction was 5% for the bulk aerosol and 14% for the ice particle residuals. The observed enrichment of BC in ice particle residuals suggests that BC may act as ice nuclei, with important implications for the indirect aerosol effect via glaciation of clouds.
Cozic, J.; Mertes, S.; Verheggen, B.; Cziczo, Dan; Gallavardin, S. J.; Walter, S.; Baltensperger, Urs; Weingartner, E.
The dependence of ice microphysics on aerosol concentration in arctic mixed-phase stratus clouds during ISDAC and M-PACE
Cloud and aerosol data acquired by the National Research Council of Canada (NRC) Convair-580 aircraft in, above, and below single-layer arctic stratocumulus cloud during the Indirect and Semi-Direct Aerosol Campaign (ISDAC) in April 2008 were used to test three aerosol indirect effects hypothesized to act in mixed-phase clouds: the riming indirect effect, the glaciation indirect effect, and the cold second indirect effect. The data showed a correlation of R= 0.75 between liquid drop number concentration, Nliq, inside cloud and ambient aerosol number concentration NPCASP below cloud. This, combined with increasing liquid water content LWC with height above cloud base and the nearly constant profile of Nliq, suggested that liquid drops were nucleated from aerosol at cloud base. No strong evidence of a riming indirect effect was observed, but a strong correlation of R = 0.69 between ice crystal number concentration Ni and NPCASP above cloud was noted. Increases in ice nuclei (IN) concentration with NPCASP above cloud combined with the subadiabatic LWC profiles suggest possible mixing of IN from cloud top consistent with the glaciation indirect effect. The higher Nice and lower effective radius rel for the more polluted ISDAC cases compared to data collected in cleaner single-layer stratocumulus conditions during the Mixed-Phase Arctic Cloud Experiment is consistent with the operation of the cold second indirect effect. However, more data in a wider variety of meteorological and surface conditions, with greater variations in aerosol forcing, are required to identify the dominant aerosol forcing mechanisms in mixed-phase arctic clouds.
Jackson, Robert C.; McFarquhar, Greg; Korolev, Alexei; Earle, Michael; Liu, Peter S.; Lawson, R. P.; Brooks, Sarah D.; Wolde, Mengistu; Laskin, Alexander; Freer, Matthew
Cloud Properties Working Group Break Out Session
(Kollias; Albecht) Q2: Growth of ice crystals in different environments: Ice initiation, ice growth regimes, precipitation formation, mixed-phase cloud lifecycle. (Korolev) Q3:...
Storm Peak Lab Cloud Property Validation
Storm Peak Lab Cloud Storm Peak Lab Cloud Property Validation Experiment (STORMVEX) Operated by the Atmospheric Radiation Measurement (ARM) Climate Research Facility for the U.S. Department of Energy, the second ARM Mobile Facility (AMF2) begins its inaugural deployment November 2010 in Steamboat Springs, Colorado, for the Storm Peak Lab Cloud Property Validation Experiment, or STORMVEX. For six months, the comprehensive suite of AMF2 instruments will obtain measurements of cloud and aerosol properties at various sites below the heavily instrumented Storm Peak Lab, located on Mount Werner at an elevation of 3220 meters. The correlative data sets that will be created from AMF2 and Storm Peak Lab will equate to between 200 and 300 in situ aircraft flight hours in liquid, mixed phase, and precipitating
8, 1175511819, 2008 mixed-phase Arctic
, process of ice phase initiation due to freezing of25 supercooled water in both saturatedACPD 8, 1175511819, 2008 Simulating mixed-phase Arctic stratus clouds I. Sednev et al. Title Page.0 License. Atmospheric Chemistry and Physics Discussions Simulating mixed-phase Arctic stratus clouds
Paris-Sud XI, Université de
Simulation of Effects of Atmospheric Aerosols on Deep Turbulent Convective Clouds Using a Spectral Microphysics Mixed-Phase Cumulus Cloud Model. Part II: Sensitivity Study
Effects of different size distributions of cloud condensational nuclei (CCN) on the evolution of deep convective clouds under dry unstable continental thermodynamic conditions are investigated using the spectral microphysics Hebrew University ...
A. Khain; A. Pokrovsky
Simulation of Effects of Atmospheric Aerosols on Deep Turbulent Convective Clouds Using a Spectral Microphysics Mixed-Phase Cumulus Cloud Model. Part I: Model Description and Possible Applications
An updated version of the spectral (bin) microphysics cloud model developed at the Hebrew University of Jerusalem [the Hebrew University Cloud Model (HUCM)] is described. The model microphysics is based on the solution of the equation system for ...
A. Khain; A. Pokrovsky; M. Pinsky; A. Seifert; V. Phillips
Impact of cloud microphysics on squall line organization
of turbulent- microphysical interactions and impact on optical properties. * Mixed-phase and ice clouds. We will use microphysical retrievals and aircraft observations from...
Cloud Properties Working Group Low Clouds Update
Cloud Properties Working Group Cloud Properties Working Group Low Clouds Update Low Clouds Update Jennifer Comstock Jennifer Comstock Dave Turner Dave Turner Andy Andy Vogelmann Vogelmann Instruments Instruments 90/150 GHz microwave radiometer 90/150 GHz microwave radiometer Deployed during COPS AMF Deployed during COPS AMF Exploring calibration w/ DPR ( Exploring calibration w/ DPR ( Crewell Crewell & & L L ö ö hnert hnert ) ) See COPS Breakout, Wednesday evening See COPS Breakout, Wednesday evening 183 GHz (GVR) deployed at the NSA 183 GHz (GVR) deployed at the NSA Neural network algorithm to retrieve PWV & LWP (Maria Neural network algorithm to retrieve PWV & LWP (Maria Cadeddu Cadeddu ) ) Potential VAP candidate (RPWG) Potential VAP candidate (RPWG)
Optical Properties and Phase of Some Midlatitude, Midlevel Clouds in ECLIPS
Several cloud optical quantities were measured for the first time in midlevel, mixed-phase clouds. These included cloud infrared emittance and absorption coefficient (10�12 ?m), effective backscatter-to-extinction ratio, and lidar depolarization ...
S. A. Young; C. M. R. Platt; R. T. Austin; G. R. Patterson
Heterogeneous chemistry of atmospheric mineral dust particles and their resulting cloud-nucleation properties
ice nucleation in ice and mixed- phase clouds are: 1. WhatWhat is the phase, hygroscopicity, and warm and ice cloudmixed phase clouds, while cirrus clouds are composed of ice
Sullivan, Ryan Christopher
of liquid, ice, and mixed-phase clouds have been processed in BBHRP for the ACRF Southern Great Plains (SGP, and phase of clouds above each ACRF site. Various approaches to retrieve the microphysical properties, including those from Microbase, the current `reference' retrieval approach in BBHRP. At the NSA, mixed-phase
Zenith Radiance Retrieval of Cloud Properties
retrievals of cloud properties retrievals of cloud properties from the AMF/COPS campaign Preliminary retrievals of cloud properties from the AMF/COPS campaign Christine Chiu, UMBC/JCET Alexander Marshak, GSFC Yuri Knyazikhin, Boston University Warren Wiscombe, GSFC Christine Chiu, UMBC/JCET Alexander Marshak, GSFC Yuri Knyazikhin, Boston University Warren Wiscombe, GSFC The cloud optical properties of interest are: The cloud optical properties of interest are: * Cloud optical depth τ - the great unknown * Radiative cloud fraction * Cloud effective drop size, r eff * Cloud optical depth τ - the great unknown * Radiative cloud fraction * Cloud effective drop size, r eff τ = 3 2 LWP r eff r eff in μm, LWP in g/m 2 The 2-ch narrow-field-of-view radiometer (2NFOV) The 2-ch narrow-field-of-view radiometer
Deployment of a Tethered-Balloon System for Microphysics and Radiative Measurements in Mixed-Phase Clouds at Ny-�lesund and South Pole
A tethered-balloon system capable of making microphysical and radiative measurements in clouds is described and examples of measurements in boundary layer stratus clouds in the Arctic and at the South Pole are presented. A 43-m3 helium-filled ...
R. Paul Lawson; Knut Stamnes; Jakob Stamnes; Pat Zmarzly; Jeff Koskuliks; Chris Roden; Qixu Mo; Michael Carrithers; Geoffrey L. Bland
Cirrus Cloud Properties from a Cloud-Resolving Model Simulation Compared to Cloud Radar Observations
Cloud radar data collected at the Atmospheric Radiation Measurement (ARM) Program's Southern Great Plains site were used to evaluate the properties of cirrus clouds that occurred in a cloud-resolving model (CRM) simulation of the 29-day summer ...
Yali Luo; Steven K. Krueger; Gerald G. Mace; Kuan-Man Xu
Cumulus Cloud Properties Derived Using Landsat Satellite Data
Landsat Multispectral Scanner (MSS) digital data are used to remotely sense cumulus cloud properties such as cloud fraction and cloud reflectance, along with the distribution of cloud number and cloud fraction as a function of cloud size. The ...
Bruce A. Wielicki; Ronald M. Welch
Investigation of Microphysical Parameterizations of Snow and Ice in Arctic Clouds during M-PACE through ModelObservation Comparisons
Investigation of Microphysical Parameterizations of Snow and Ice in Arctic Clouds during M the microphysical properties of Arctic mixed-phase stratocumulus. Intensive measurements taken during the Department of Energy Atmospheric Radiation Measurement Program Mixed-Phase Arctic Cloud Experiment (M
Solomon, Amy
Mixed-Phase Microphysics and Cloud Electrification
A number of experimental studies have shown that sublimating ice acquires negative charge and ice undergoing vapor deposition acquires positive charge. Microphysical calculations are performed to determine the diffusional state (i.e., sublimation ...
E. R. Williams; R. Zhang; J. Rydock
Cloud properties derived from the High Spectral Resolution Lidar...
Cloud properties derived from the High Spectral Resolution Lidar during MPACE Eloranta, Edwin University of Wisconsin Category: Field Campaigns Cloud properties were derived from...
A Potential Role for Immersion Freezing in Arctic Mixed-Phase Stratus
Potential Role for Immersion Freezing in Arctic Mixed-Phase Stratus Potential Role for Immersion Freezing in Arctic Mixed-Phase Stratus Gijs de Boer, Edwin W. Eloranta, Tempei Hashino, and Gregory J. Tripoli The University of Wisconsin - Madison (1) Introduction Ice formation appears to a dominant factor controlling the lifecycle of Arctic mixed-phase clouds. To date, our understanding of ice formation in these long-lasting cloud structures does not explain the formation of observed ice amounts. Particularly puzzling are observa-
Q. J. R. Meteorol. Soc. (2006), 132, pp. 16931715 doi: 10.1256/qj.05.145 Evaluation of a large-eddy model simulation of a mixed-phase altocumulus
of mixed-phase clouds, the case shows the importance of using: (i) separate prognostic ice and liquid water-eddy model simulation of a mixed-phase altocumulus cloud using microwave radiometer, lidar and Doppler radar February 2006) SUMMARY Using the Met Office large-eddy model (LEM) we simulate a mixed-phase altocumulus
Hogan, Robin
MODIS Cloud-Top Property Refinements for Collection 6
This paper summarizes the Collection-6 refinements in the Moderate Resolution Imaging Spectroradiometer (MODIS) operational cloud-top properties algorithm. The focus is on calibration improvements and on cloud macrophysical properties including ...
Bryan A. Baum; W. Paul Menzel; Richard A. Frey; David C. Tobin; Robert E. Holz; Steve A. Ackerman; Andrew K. Heidinger; Ping Yang
An Arctic Springtime Mixed-Phase Cloudy Boundary Layer Observed during SHEBA
The microphysical characteristics, radiative impact, and life cycle of a long-lived, surface-based mixed-layer, mixed-phase cloud with an average temperature of approximately ?20�C are presented and discussed. The cloud was observed during the ...
P. Zuidema; B. Baker; Y. Han; J. Intrieri; J. Key; P. Lawson; S. Matrosov; M. Shupe; R. Stone; T. Uttal
A High Resolution Hydrometer Phase Classifier Based on Analysis of Cloud Radar Doppler Spectra.
The lifecycle and radiative properties of clouds are highly sensitive to the phase of their hydrometeors (i.e., liquid or ice). Knowledge of cloud phase is essential for specifying the optical properties of clouds, or else, large errors can be introduced in the calculation of the cloud radiative fluxes. Current parameterizations of cloud water partition in liquid and ice based on temperature are characterized by large uncertainty (Curry et al., 1996; Hobbs and Rangno, 1998; Intriery et al., 2002). This is particularly important in high geographical latitudes and temperature ranges where both liquid droplets and ice crystal phases can exist (mixed-phase cloud). The mixture of phases has a large effect on cloud radiative properties, and the parameterization of mixed-phase clouds has a large impact on climate simulations (e.g., Gregory and Morris, 1996). Furthermore, the presence of both ice and liquid affects the macroscopic properties of clouds, including their propensity to precipitate. Despite their importance, mixed-phase clouds are severely understudied compared to the arguably simpler single-phase clouds. In-situ measurements in mixed-phase clouds are hindered due to aircraft icing, difficulties distinguishing hydrometeor phase, and discrepancies in methods for deriving physical quantities (Wendisch et al. 1996, Lawson et al. 2001). Satellite-based retrievals of cloud phase in high latitudes are often hindered by the highly reflecting ice-covered ground and persistent temperature inversions. From the ground, the retrieval of mixed-phase cloud properties has been the subject of extensive research over the past 20 years using polarization lidars (e.g., Sassen et al. 1990), dual radar wavelengths (e.g., Gosset and Sauvageot 1992; Sekelsky and McIntosh, 1996), and recently radar Doppler spectra (Shupe et al. 2004). Millimeter-wavelength radars have substantially improved our ability to observe non-precipitating clouds (Kollias et al., 2007) due to their excellent sensitivity that enables the detection of thin cloud layers and their ability to penetrate several non-precipitating cloud layers. However, in mixed-phase clouds conditions, the observed Doppler moments are dominated by the highly reflecting ice crystals and thus can not be used to identify the cloud phase. This limits our ability to identify the spatial distribution of cloud phase and our ability to identify the conditions under which mixed-phase clouds form.
Luke,E.; Kollias, P.
Relating Satellite-Observed Cloud Properties from MODIS to Meteorological Conditions for Marine Boundary Layer Clouds
This study examines 6 yr of cloud properties observed by the Moderate Resolution Imaging Spectroradiometer (MODIS) on board the NASA Terra satellite in five prominent marine boundary layer (MBL) cloud regions (California, Peru, Canary, Angola, ...
Guang J. Zhang; Andrew M. Vogelmann; Michael P. Jensen; William D. Collins; Edward P. Luke
The Retrieval of Ice-Cloud Properties from Cloud Radar and Lidar Synergy
Clouds are an important component of the earth�s climate system. A better description of their microphysical properties is needed to improve radiative transfer calculations. In the framework of the Earth, Clouds, Aerosols, and Radiation Explorer (...
Claire Tinel; Jacques Testud; Jacques Pelon; Robin J. Hogan; Alain Protat; Julien Delano�; Dominique Bouniol
A Summary of the Physical Properties of Cirrus Clouds
A review of existing literature is made to determine typical values for the physical properties cirrus clouds. The properties examined (with typical values and measured ranges) are cloud-center altitude (9 km, 4 to 20 km), cloud thickness (1.5 km,...
David R. Dowling; Lawrence F. Radke
Cloud Properties inferred from 8?12-�m Data
A trispectral combination of observations at 8-, 11-, and 12-�m bands is suggested for detecting cloud and cloud properties in the infrared. Atmospheric ice and water vapor absorption peak in opposite halves of the window region so that positive ...
Kathleen I. Strabala; Steven A. Ackerman; W. Paul Menzel
Statistics of Cloud Optical Properties from Airborne Lidar Measurements
Accurate knowledge of cloud optical properties, such as extinction-to-backscatter ratio and depolarization ratio, can have a significant impact on the quality of cloud extinction retrievals from lidar systems because parameterizations of these ...
John E. Yorks; Dennis L. Hlavka; William D. Hart; Matthew J. McGill
Posters Cloud Microphysical and Radiative Properties Measured
7 7 Posters Cloud Microphysical and Radiative Properties Measured by Combined Lidar, Radar, and Infrared Radiometer W. L. Eberhard and J. M. Intrieri National Oceanic and Atmospheric Administration Environmental Technology Laboratory Boulder, Colorado K. P. Chan and G. Feingold Cooperative Institute for Research in Environmental Sciences Boulder, Colorado also an order of magnitude smaller. These features make simple approximations in scattering calculations adequate for some applications, e.g., Eberhard (1993a). They also provide some unique capabilities, especially the technique described below for measuring drop sizes. One of the four IDP tasks is to characterize cloud signatures obtained by CO 2 lidar. For instance, our earlier work discovered that depolarization from ice particles was almost
Computing and Partitioning Cloud Feedbacks Using Cloud Property Histograms. Part I: Cloud Radiative Kernels
This study proposes a novel technique for computing cloud feedbacks using histograms of cloud fraction as a joint function of cloud-top pressure (CTP) and optical depth (?). These histograms were generated by the International Satellite Cloud ...
Mark D. Zelinka; Stephen A. Klein; Dennis L. Hartmann
ARM - Publications: Science Team Meeting Documents: Cloud Property...
Cloud Property Retrievals using AIRS data during MPACE Huang, Allen University of Wisconsin Li, Jun University of Wisconsin-Madison Baggett, Kevin University of Wisconsin-Madison...
Application of Stochastic Radiative Transfer Theory to the ARM Cloud-Radiative Parameterization Problem
This project had two primary goals: (1) development of stochastic radiative transfer as a parameterization that could be employed in an AGCM environment, and (2) exploration of the stochastic approach as a means for representing shortwave radiative transfer through mixed-phase layer clouds. To achieve these goals, climatology of cloud properties was developed at the ARM CART sites, an analysis of the performance of the stochastic approach was performed, a simple stochastic cloud-radiation parameterization for an AGCM was developed and tested, a statistical description of Arctic mixed phase clouds was developed and the appropriateness of stochastic approach for representing radiative transfer through mixed-phase clouds was assessed. Significant progress has been made in all of these areas and is detailed in the final report.
Dana E. Veron
Study of ice cloud properties using infrared spectral data
The research presented in this thesis involves the study of ice cloud microphysical and optical properties using both hyperspectral and narrowband infrared spectral data. First, ice cloud models are developed for the Infrared Atmospheric Sounding Interferometer (IASI) instrument onboard the METOP-A satellite, which provide the bulk-scattering properties of these clouds for the 8461 IASI channels between 645 and 2760 cm-1. We investigate the sensitivity of simulated brightness temperatures in this spectral region to the bulk-scattering properties of ice clouds containing individual ice crystal habits as well as for one habit distribution. The second part of this thesis describes an algorithm developed to analyze the sensitivity of simulated brightness temperatures at 8.5 and 11.0 �m to changes in effective cloud temperature by adjusting cloud top height and geometric thickness in a standard tropical atmosphere. Applicability of using these channels in a bi-spectral approach to retrieve cirrus cloud effective particle size and optical thickness is assessed. Finally, the algorithm is applied to the retrieval of these ice cloud properties for a case of single-layered cirrus cloud over a tropical ocean surface using measurements from the Moderate Resolution Infrared Spectroradiometer (MODIS). Cloud top height and geometric thickness in the profile are adjusted to assess the influence of effective cloud temperature on the retrieval.
Garrett, Kevin James
Relating Cirrus Cloud Properties to Observed Fluxes: A Critical Assessment
The accuracy needed in cirrus cloud scattering and microphysical properties is quantified such that the radiative effect on climate can he determined. Our ability to compute and observe these properties to within needed accuracies is assessed, ...
A. M. Vogelmann; T. P. Ackerman
Radar and Radiation Properties of Ice Clouds
The authors derive relations of the equivalent radar reflectivity Ze and extinction coefficient ? of ice clouds and confirm the theory by in situ aircraft observations during the First International Satellite Cloud Climatology Project Regional ...
David Atlas; Sergey Y. Matrosov; Andrew J. Heymsfield; Ming-Dah Chou; David B. Wolff
A Potential Role for Immersion Freezing in Arctic Mixed-Phase Stratus Gijs de Boer,Edwin W.Eloranta,Tempei Hashino,and Gregory J.Tripoli
to a dominant factor controlling the lifecycle of Arctic mixed-phase clouds. To date, our understanding of ice Stratus from M-PACE Mixed-Phase Layer Ice Precipitation "Bursts" Time (UT) Altitude(km) Lidar backscatter. - Additionally, Shupe illustrated that ice water content and liquid water content seem to vary in phase with each
Radiosonde observations at Pt. Reyes and cloud properties retrieved from
Radiosonde observations at Pt. Reyes and cloud properties retrieved from Radiosonde observations at Pt. Reyes and cloud properties retrieved from GOES-WEST Inoue, Toshiro MRI/JMA Category: Field Campaigns Low-level cloud formed off the west coast of continents plays an important role in general circulation and climate. Marine Stratus Radiation Aerosol and Drizzle (MASRAD) was conducted at the ARM mobile site deployed at Pt Reyes, California during April to September. Here, we studied the relationship between meteorological parameters observed by GPS sonde and cloud properties observed from GOES-WEST during the MASRAD intensive operational period. Cloud properties are retrieved from VISST (Visible Infrared Solar-infrared Split window Technique). The vertical profile of stability, relative humidity (RH) and wind speed observed by GPS sonde are
Global, Seasonal Cloud Variations from Satellite Radiance Measurements. Part II. Cloud Properties and Radiative Effects
Global, daily, visible and infrared radiance measurements from the NOAA-5 Scanning Radiometer (SR) are analyzed for the months of January, April, July and October 1977 to infer cloud and surface radiative properties and their effects on the Earth ...
William B. Rossow; Andrew A. Lacis
Satellite Determination of Stratus Cloud Microphysical Properties
Satellite measurements of liquid water path from SSM/I, broadband albedo from ERBE, and cloud characteristics from ISCCP are used to study stratus regions. An average cloud liquid water path of 0.120 � 0.032 kg m?2 is derived by dividing the ...
Paquita Zuidema; Dennis L. Hartmann
Effects of Cloud Optical Property Feedbacks on the Greenhouse Warming
Cloud optical properties, in particular the optical thickness, affect the earth-atmosphere radiation budget, and their potential changes associated with climate changes may induce feedback effect. A one-dimensional radiative-forcing model was ...
Gyula Molnar; Wei-Chyung Wang
What Controls Stratocumulus Radiative Properties? Lagrangian Observations of Cloud Evolution
Marine stratocumulus clouds have a large impact on the earth�s radiation budget. Their optical properties vary on two distinct timescales, one associated with the diurnal cycle of solar insolation and another with the downstream transition to ...
Robert Pincus; Marcia B. Baker; Christopher S. Bretherton
Cloud Scavenging Effects on Aerosol Radiative and Cloud-nucleating Properties - Final Technical Report
The optical properties of aerosol particles are the controlling factors in determining direct aerosol radiative forcing. These optical properties depend on the chemical composition and size distribution of the aerosol particles, which can change due to various processes during the particles� lifetime in the atmosphere. Over the course of this project we have studied how cloud processing of atmospheric aerosol changes the aerosol optical properties. A counterflow virtual impactor was used to separate cloud drops from interstitial aerosol and parallel aerosol systems were used to measure the optical properties of the interstitial and cloud-scavenged aerosol. Specifically, aerosol light scattering, back-scattering and absorption were measured and used to derive radiatively significant parameters such as aerosol single scattering albedo and backscatter fraction for cloud-scavenged and interstitial aerosol. This data allows us to demonstrate that the radiative properties of cloud-processed aerosol can be quite different than pre-cloud aerosol. These differences can be used to improve the parameterization of aerosol forcing in climate models.
Ogren, John A.; Sheridan, Patrick S.; Andrews, Elisabeth
Measuring Cloud Properties from Space: A Review
A brief review of observations of clouds using satellites highlights open issues and directions for future studies. The key one is improved treatment of the effects of small-scale spatial inhomogeneity in remote sensing data analyses and in the ...
William B. Rossow
Cirrus clouds in a global climate model with a statistical cirrus cloud scheme
supersaturation in mixed-phase clouds is the saturation vapor pressure weighted by the proportions of ice to be in the liquid phase for clouds warmer than -35ºC, and is assumed to be in the ice phase for cirrus clouds. The conversion of this detrained condensate from liquid phase into the ice phase in the mixed-phase clouds
Meskhidze, Nicholas
Using MSG-SEVIRI Cloud Physical Properties and Weather Radar Observations for the Detection of Cb/TCu Clouds
A new automated daytime cumulonimbus/towering cumulus (Cb/TCu) cloud detection method for the months of May�September is presented that combines information on cloud physical properties retrieved from the Spinning Enhanced Visible and Infrared ...
Cintia Carbajal Henken; Maurice J. Schmeits; Hartwig Deneke; Rob A. Roebeling
The Composite Characteristics of Cirrus Clouds: Bulk Properties Revealed by One Year of Continuous Cloud Radar Data
The properties of midlatitude cirrus clouds are examined using one year of continuous vertically pointing millimeter-wave cloud radar data collected at the Atmospheric Radiation Measurement Program Southern Great Plains site in Oklahoma. The goal ...
Gerald G. Mace; Eugene E. Clothiaux; Thomas P. Ackerman
In Situ Observations of the Microphysical Properties of Wave, Cirrus, and Anvil Clouds. Part I: Wave Clouds
The microphysical properties of wave clouds based on data collected during 17 missions flown by a Learjet research aircraft are presented and discussed. This extensive dataset expands upon previous aircraft studies of wave clouds and introduces ...
Brad A. Baker; R. Paul Lawson
In Situ Observations of Cirrus Cloud Microphysical Properties Using the Counterflow Virtual Impactor
This study presents a new technique for making in situ measurements of cirrus cloud microphysical properties. Sampling of cirrus clouds was performed using a counterflow virtual impactor (CVI). The CVI was used to sample cloud elements larger ...
K. B. Noone; K. J. Noone; J. Heintzenberg; J. Str�m; J. A. Ogren
Impact of Ice Crystal Roughness on Satellite Retrieved Cloud Properties
Ice Crystal Roughness on Satellite Retrieved Cloud Properties Ice Crystal Roughness on Satellite Retrieved Cloud Properties P. Minnis 1 , P. W. Heck 2 , R. F. Arduini 3 , R. Palikonda 3 , J. K. Ayers 3 , M. M. Khaiyer 3 , P. Yang 4 , Y. Xie 4 3 Science Systems & Applications, Inc. Hampton, VA 1 NASA Langley Research Center Hampton, VA Current Cirrus Models Inadequate Cirrus cloud optical depths τ (heights z e ) are often over (under) estimated when derived from solar reflectances. In situ data suggest smaller asymmetry factors, g, than used in most retrieval models. Multi-angle measurements point to smoother phase functions than for solid, smooth xtals. Calculations show that solid crystals with roughened facets or embedded bubbles --both observed in real cirrus particles-- yield smoother phase functions & smaller g
ARM - Field Campaign - Colorado: The Storm Peak Lab Cloud Property
govCampaignsColorado: The Storm Peak Lab Cloud Property Validation govCampaignsColorado: The Storm Peak Lab Cloud Property Validation Experiment (STORMVEX) Campaign Links STORMVEX Website Related Campaigns Colorado: CFH/CMH Deployment to StormVEx 2011.02.01, Mace, AMF Colorado: SP2 Deployment at StormVEx 2010.11.15, Sedlacek, AMF Colorado : Cavity Attenuated Phase Shift 2010.11.15, Massoli, AMF Colorado: Infrared Thermometer (IRT) 2010.11.15, Mace, AMF Colorado: StormVEX Aerosol Size Distribution 2010.11.15, Hallar, AMF Colorado: Direct Measurements of Snowfall 2010.11.15, McCubbin, AMF Colorado: Thunderhead Radiative Flux Analysis Campaign 2010.11.15, Long, AMF Colorado: Ice Nuclei and Cloud Condensation Nuclei Characterization 2010.11.15, Cziczo, AMF Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA.
A Characterization of Cirrus Cloud Properties That Affect Laser Propagation
Future high-altitude laser systems may be affected by cirrus clouds. Laser transmission models were applied to measured and retrieved cirrus properties to determine cirrus impact on power incident on a target or receiver. A major goal was to see ...
Donald C. Norquist; Paul R. Desrochers; Patrick J. McNicholl; John R. Roadcap
Correlated k-Distribution Treatment of Cloud Optical Properties and Related Radiative Impact
A new scheme of water cloud optical properties is proposed for correlated k-distribution (CKD) models, in which the correlation in spectral distributions between the gaseous absorption coefficient and cloud optical properties is maintained. This ...
Peng Lu; Hua Zhang; Jiangnan Li
Aircraft Observations of Sub-cloud Aerosol and Convective Cloud Physical Properties
This research focuses on aircraft observational studies of aerosol-cloud interactions in cumulus clouds. The data were collected in the summer of 2004, the spring of 2007 and the mid-winter and spring of 2008 in Texas, central Saudi Arabia and Istanbul, Turkey, respectively. A set of 24 pairs of sub-cloud aerosol and cloud penetration data are analyzed. Measurements of fine and coarse mode aerosol concentrations from 3 different instruments were combined and fitted with lognormal distributions. The fit parameters of the lognormal distributions are compared with cloud droplet effective radii retrieved from 260 cloud penetrations. Cloud condensation nuclei (CCN) measurements for a subset of 10 cases from the Istanbul region are compared with concentrations predicted from aerosol size distributions. Ammonium sulfate was assumed to represent the soluble component of aerosol with dry sizes smaller than 0.5 mm and sodium chloride for aerosol larger than 0.5 mm. The measured CCN spectrum was used to estimate the soluble fraction. The correlations of the measured CCN concentration with the predicted CCN concentration were strong (R2 > 0.89) for supersaturations of 0.2, 0.3 and 0.6%. The measured concentrations were typically consistent with an aerosol having a soluble fraction between roughly 0.5 and 1.0, suggesting a contribution of sulfate or some other similarly soluble inorganic compound. The predicted CCN were found to vary by +or-3.7% when the soluble fraction was varied by 0.1. Cumulative aerosol concentrations at cutoff dry diameters of 1.1, 0.1 and 0.06 mm were found to be correlated with cloud condensation nuclei concentrations but not with maximum cloud base droplet concentrations. It is also shown that in some cases the predominant mechanisms involved in the formation of precipitation were altered and modified by the aerosol properties. This study suggests that CCN-forced variations in cloud droplet number concentration can change the effective radius profile and the type of precipitation hydrometeors. These differences may have a major impact on the global hydrological cycle and energy budget.
Axisa, Duncan
Posters Ship-Based Measurements of Cloud Optical Properties
7 7 Posters Ship-Based Measurements of Cloud Optical Properties During the Atlantic Stratocumulus Transition Experiment A. B. White Cooperative Institute for Research in Environmental Sciences University of Colorado at Boulder National Oceanic and Atmospheric Administration Boulder, Colorado C. W. Fairall National Oceanic and Atmospheric Administration Environmental Research Laboratories Environmental Technology Laboratory Boulder, Colorado Introduction The Atlantic Stratocumulus Transition Experiment (ASTEX), conducted in June 1992, was designed with the broad goal of improving the dynamical, radiative, and microphysical models of marine boundary layer (MBL) clouds. This goal was pursued by combining measurements from a number of different platforms including aircraft,
Autumnal Mixed-Phase Cloudy Boundary Layers in the Arctic
Two mixed-phase cloudy boundary layer events observed over the Arctic ice pack in autumn are extensively analyzed. The local dynamic and thermodynamic structure of the boundary layers is determined from aircraft measurements including analysis of ...
James O. Pinto
Testing cloud microphysics parameterizations in NCAR CAM5 with ISDAC and M-PACE observations
ice nucleation parameterization slightly improves the model performance for low-level mixed-phase ice loss by enhancing ice-albedo feedbacks [Kay et al., 2008]. Arctic clouds are often mixed-phase (i-Direct Aerosol Campaign (ISDAC) and Mixed-Phase Arctic Cloud Experiment (M-PACE), which were conducted at its
The near-infrared colors of the planets directly imaged around the A star HR 8799 are much redder than most field brown dwarfs of the same effective temperature. Previous theoretical studies of these objects have concluded that the atmospheres of planets b, c, and d are unusually cloudy or have unusual cloud properties. Some studies have also found that the inferred radii of some or all of the planets disagree with expectations of standard giant planet evolution models. Here, we compare the available data to the predictions of our own set of atmospheric and evolution models that have been extensively tested against observations of field L and T dwarfs, including the reddest L dwarfs. Unlike some previous studies, we require mutually consistent choices for effective temperature, gravity, cloud properties, and planetary radius. This procedure thus yields plausible values for the masses, effective temperatures, and cloud properties of all three planets. We find that the cloud properties of the HR 8799 planets are not unusual but rather follow previously recognized trends, including a gravity dependence on the temperature of the L to T spectral transition-some reasons for which we discuss. We find that the inferred mass of planet b is highly sensitive to whether or not we include the H- and the K-band spectrum in our analysis. Solutions for planets c and d are consistent with the generally accepted constraints on the age of the primary star and orbital dynamics. We also confirm that, like in L and T dwarfs and solar system giant planets, non-equilibrium chemistry driven by atmospheric mixing is also important for these objects. Given the preponderance of data suggesting that the L to T spectral type transition is gravity dependent, we present an exploratory evolution calculation that accounts for this effect. Finally we recompute the bolometric luminosity of all three planets.
Marley, Mark S. [NASA Ames Research Center, MS-245-3, Moffett Field, CA 94035 (United States); Saumon, Didier [Los Alamos National Laboratory, Mail Stop F663, Los Alamos, NM 87545 (United States); Cushing, Michael [Department of Physics and Astronomy, The University of Toledo, 2801 West Bancroft Street, Toledo, OH 43606 (United States); Ackerman, Andrew S. [NASA Goddard Institute for Space Studies, 2880 Broadway, New York, NY 10025 (United States); Fortney, Jonathan J. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Freedman, Richard, E-mail: firstname.lastname@example.com, E-mail: email@example.com, E-mail: firstname.lastname@example.com, E-mail: firstname.lastname@example.com, E-mail: firstname.lastname@example.com, E-mail: email@example.com [SETI Institute and NASA Ames Research Center, MS-245-3, Moffett Field, CA 94035 (United States)
ARM - Field Campaign - Fall 1997 Cloud IOP
and with surface instruments. Cloud types of interest included single-layer liquid phase, ice-phase, and mixed-phase clouds, as well as multi-layered conditions. To some degree,...
ARM - PI Product - Cloud Properties and Radiative Heating Rates for TWP
ProductsCloud Properties and Radiative Heating Rates for ProductsCloud Properties and Radiative Heating Rates for TWP Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send PI Product : Cloud Properties and Radiative Heating Rates for TWP 2002.01.01 - 2012.02.08 Site(s) TWP General Description A cloud properties and radiative heating rates dataset is presented where cloud properties retrieved using lidar and radar observations are input into a radiative transfer model to compute radiative fluxes and heating rates at three ARM sites located in the Tropical Western Pacific (TWP) region. The cloud properties retrieval is a conditional retrieval that applies various retrieval techniques depending on the available data, that is if lidar, radar or both instruments detect cloud. This Combined Remote
Parameterizing Size Distribution in Ice Clouds
PARAMETERIZING SIZE DISTRIBUTIONS IN ICE CLOUDS David L. Mitchell and Daniel H. DeSlover ABSTRACT An outstanding problem that contributes considerable uncertainty to Global Climate Model (GCM) predictions of future climate is the characterization of ice particle sizes in cirrus clouds. Recent parameterizations of ice cloud effective diameter differ by a factor of three, which, for overcast conditions, often translate to changes in outgoing longwave radiation (OLR) of 55 W m-2 or more. Much of this uncertainty in cirrus particle sizes is related to the problem of ice particle shattering during in situ sampling of the ice particle size distribution (PSD). Ice particles often shatter into many smaller ice fragments upon collision with the rim of the probe inlet tube. These small ice artifacts are counted as real ice crystals, resulting in anomalously high concentrations of small ice crystals (D < 100 �m) and underestimates of the mean and effective size of the PSD. Half of the cirrus cloud optical depth calculated from these in situ measurements can be due to this shattering phenomenon. Another challenge is the determination of ice and liquid water amounts in mixed phase clouds. Mixed phase clouds in the Arctic contain mostly liquid water, and the presence of ice is important for determining their lifecycle. Colder high clouds between -20 and -36 oC may also be mixed phase but in this case their condensate is mostly ice with low levels of liquid water. Rather than affecting their lifecycle, the presence of liquid dramatically affects the cloud optical properties, which affects cloud-climate feedback processes in GCMs. This project has made advancements in solving both of these problems. Regarding the first problem, PSD in ice clouds are uncertain due to the inability to reliably measure the concentrations of the smallest crystals (D < 100 �m), known as the �small mode�. Rather than using in situ probe measurements aboard aircraft, we employed a treatment of ice cloud optical properties formulated in terms of PSD parameters in combination with remote measurements of thermal radiances to characterize the small mode. This is possible since the absorption efficiency (Qabs) of small mode crystals is larger at 12 �m wavelength relative to 11 �m wavelength due to the process of wave resonance or photon tunneling more active at 12 �m. This makes the 12/11 �m absorption optical depth ratio (or equivalently the 12/11 �m Qabs ratio) a means for detecting the relative concentration of small ice particles in cirrus. Using this principle, this project tested and developed PSD schemes that can help characterize cirrus clouds at each of the three ARM sites: SGP, NSA and TWP. This was the main effort of this project. These PSD schemes and ice sedimentation velocities predicted from them have been used to test the new cirrus microphysics parameterization in the GCM known as the Community Climate Systems Model (CCSM) as part of an ongoing collaboration with NCAR. Regarding the second problem, we developed and did preliminary testing on a passive thermal method for retrieving the total water path (TWP) of Arctic mixed phase clouds where TWPs are often in the range of 20 to 130 g m-2 (difficult for microwave radiometers to accurately measure). We also developed a new radar method for retrieving the cloud ice water content (IWC), which can be vertically integrated to yield the ice water path (IWP). These techniques were combined to determine the IWP and liquid water path (LWP) in Arctic clouds, and hence the fraction of ice and liquid water. We have tested this approach using a case study from the ARM field campaign called M-PACE (Mixed-Phase Arctic Cloud Experiment). This research led to a new satellite remote sensing method that appears promising for detecting low levels of liquid water in high clouds typically between -20 and -36 oC. We hope to develop this method in future research.
DeSlover, Daniel; Mitchell, David L.
Determination of the Radiative Properties of Stratiform Clouds from a Nadir-Looking 95-GHz Radar
Several space agencies are presently considering missions with active instruments (radar, lidar), which are able to document cloud stratification and cloud microphysical properties on the global scale. The objective of this paper is to develop an ...
A. Guyot; J. Testud; T. P. Ackerman
Seasonal Variation of the Physical Properties of Marine Boundary Layer Clouds off the California Coast
Marine boundary layer (MBL) clouds can significantly regulate the sensitivity of climate models, yet they are currently poorly simulated. This study aims to characterize the seasonal variations of physical properties of these clouds and their ...
Wuyin Lin; Minghua Zhang; Norman G. Loeb
High and Dry: New Observations of Tropospheric and Cloud Properties above the Greenland Ice Sheet
Cloud and atmospheric properties strongly influence the mass and energy budgets of the Greenland Ice Sheet (GIS). To address critical gaps in the understanding of these systems, a new suite of cloud- and atmosphere-observing instruments has been installed ...
Matthew D. Shupe; David D. Turner; Von P. Walden; Ralf Bennartz; Maria P. Cadeddu; Benjamin B. Castellani; Christopher J. Cox; David R. Hudak; Mark S. Kulie; Nathaniel B. Miller; Ryan R. Neely; III; William D. Neff; Penny M. Rowe
An Estimate of Low-Cloud Feedbacks from Variations of Cloud Radiative and Physical Properties with Sea Surface Temperature on Interannual Time Scales
Simulations of climate change have yet to reach a consensus on the sign and magnitude of the changes in physical properties of marine boundary layer clouds. In this study, the authors analyze how cloud and radiative properties vary with SST ...
Zachary A. Eitzen; Kuan-Man Xu; Takmeng Wong
Systematic Flights Obtain Long-Term Data Set of Cloud Properties
Systematic Flights Obtain Long-Term Data Set of Cloud Properties Systematic Flights Obtain Long-Term Data Set of Cloud Properties Beginning in January 2009, the U.S. Department of Energy's Atmospheric Radiation Measurement (ARM) Climate Research Facility is sponsoring the first-of-its-kind long-term airborne research campaign to obtain data from low-level clouds above its Southern Great Plains (SGP) site. The five-month campaign is centered near Lamont, Oklahoma, a mid-latitude region that experiences a wide range of cloud types, including the "thin" clouds that are the focus of the campaign. Thin clouds contain so little water that the sun can be seen through them. Scientists refer to such clouds as "clouds with low-optical water depth," or CLOWD. Because these clouds are often tenuous and scattered, even some of the best
ISCCP Cloud Properties Associated with Standard Cloud Types Identified in Individual Surface Observations
Individual surface weather observations from land stations and ships are compared with individual cloud retrievals of the International Satellite Cloud Climatology Project (ISCCP), stage C1, for an 8-yr period (1983�91) to relate cloud optical ...
Carole J. Hahn; William B. Rossow; Stephen G. Warren
Improvements in Representations of Cloud Microphysics for BBHRP and Models using Data Collected during M-PACE and TWP-ICE
In our research we proposed to use data collected during the 2004 Mixed-Phase Arctic Cloud Experiment (MPACE) and the 2006 Tropical Warm Pool International Cloud Experiment (TWP-ICE) to improve retrievals of ice and mixed-phase clouds, to improve our understanding of how cloud and radiative processes affect cloud life cycles, and to develop and test methods for using ARM data more effectively in model. In particular, we proposed to: 1) use MPACE in-situ data to determine how liquid water fraction and cloud ice and liquid effective radius (r{sub ei} and r{sub ew}) vary with temperature, normalized cloud altitude and other variables for Arctic mixed-phase clouds, and to use these data to evaluate the performance of model parameterization schemes and remote sensing retrieval algorithms; 2) calculate rei and size/shape distributions using TWP-ICE in-situ data, investigate their dependence on cirrus type (oceanic or continental anvils or cirrus not directly traced to convection), and develop and test representations for MICROBASE; 3) conduct fundamental research enhancing our understanding of cloud/radiative interactions, concentrating on effects of small crystals and particle shapes and sizes on radiation; and 4) improve representations of microphysical processes for models (fall-out, effective density, mean scattering properties, rei and rew) and provide them to ARM PIs. In the course of our research, we made substantial progress on all four goals.
Greg M. McFarquhar
Cloud Type and Macrophysical Property Retrieval Using Multiple Remote Sensors
A cloud detection algorithm based on ground-based remote sensors has been developed that can differentiate among various atmospheric targets such as ice and water clouds, virga, precipitation, and aerosol layers. Standard cloud type and ...
Zhien Wang; Kenneth Sassen
Aerosol Size Distribution, Particle Concentration, and Optical Property Variability near Caribbean Trade Cumulus Clouds: Isolating Effects of Vertical Transport and Cloud Processing from Humidification Using Aircraft Measurements
This paper examines the effect of trade wind cumulus clouds on aerosol properties in the near-cloud environment using data from the Rain in Cumulus over the Ocean (RICO) campaign. Aerosol size distributions, particle concentrations, and optical ...
Robert M. Rauber; Guangyu Zhao; Larry Di Girolamo; Maril� Col�n-Robles
Modeling clouds observed at SHEBA using a bulk microphysics parameterization implemented into a single-column model
cloud fraction, that is, underpredicting the frequency of liquid- or mixed-phase clouds. The mean ice associated with leads, ``clear-sky'' ice crystal precipitation, and persis- tent mixed-phase clouds. BiasesModeling clouds observed at SHEBA using a bulk microphysics parameterization implemented
The Radiative, Cloud, and Thermodynamic Properties of the Major Tropical Western Pacific Cloud Regimes
This study investigates the radiative, cloud, and thermodynamic characteristics of the atmosphere separated into objectively defined cloud regimes in the tropical western Pacific (TWP). A cluster analysis is applied to 2 yr of daytime-only data ...
Christian Jakob; George Tselioudis; Timothy Hume
Properties of Tropical Cloud Ensembles Estimated Using a Cloud Model and an Observed Updraft Population
A simple cloud model is developed which is designed for both diagnostic studies and mesoscale cumulus parameterization experiments. The cloud model is combined with an observed population of tropical convective updrafts and used to examine the ...
William M. Frank; Charles Cohen
Radiation Properties and Emissivity Parameterization of High Level Thin Clouds
To parameterize emissivity of clouds at 11 ?m, a study has been made in an effort to understand the radiation field of thin clouds. The contributions to the intensity and flux from different sources and through different physical processes are ...
Man-Li C. Wu
Non-stoichiometric mixed-phase titania photocatalyst
A mixed anatase-rutile phase, non-stoichiometric titania photocatalyst material is a highly reactive and is a UV and visible light responsive photocastalyst in the as-deposited condition (i.e. without the need for a subsequent thermal treatment). The mixed phase, non-stoichiometric titania thin film material is non-stoichiometric in terms of its oxygen content such that the thin film material shows a marked red-shift in photoresponse.
Chen, Le (Lakewood, CO); Gray, Kimberly A. (Evanston, IL); Graham, Michael E. (Evanston, IL)
Cloud microphysical properties retrieved from downwelling infrared radiance measurements made at Eureka, Nunavut, Canada (2006-2009)
The radiative properties of clouds are related to cloud microphysical and optical properties, including water path, optical depth, particle size, and thermodynamic phase. Ground-based observations provide high quality, long-term, continuous ...
Christopher J. Cox; David D. Turner; Penny M. Rowe; Matthew D. Shupe; Von P. Walden
Synoptic sensitivities of subtropical clouds separating aerosol effects from meteorology
identi?ed as liquid, ice, mixed phase, or uncertain. Here wePhase Infrared Day Histogram Counts Cloud Fraction Liquid Cloud Fraction Iceice as well as the di?erent temperatures at which each phase
Mauger, Guillaume S.
Unraveling the origins of electromechanical response in mixed-phase Bismuth Ferrite
The origin of giant electromechanical response in a mixed-phase rhombohedral-tetragonal BiFeO3 thin film is probed using sub-coercive scanning probe microscopy based multiple-harmonic measurements. Significant contributions to the strain arise from a second-order harmonic response localized at the phase boundaries. Strain and dissipation data, backed by thermodynamic calculations suggest that the source of the enhanced electromechanical response is the motion of phase boundaries. These findings elucidate the key role of labile phase boundaries, both natural and artificial, in achieving thin films with giant electromechanical properties.
Vasudevan, Rama K [ORNL; Okatan, M. B. [University of New South Wales; Liu, Y. Y. [University of Washington, Seattle; Jesse, Stephen [ORNL; Yang, J.-C. [University of California, Berkeley; Liang, W. -I. [National Chiao Tung University, Hsinchu, Taiwan; Chu, Ying-Hao [National Chiao Tung University, Hsinchu, Taiwan; Li, J. Y. [University of Washington, Seattle; Kalinin, Sergei V [ORNL; Valanoor, Nagarajan V [ORNL
The Dependence of Cirrus Cloud-Property Retrievals on Size-Distribution
The Dependence of Cirrus Cloud-Property Retrievals on Size-Distribution The Dependence of Cirrus Cloud-Property Retrievals on Size-Distribution Shape d'Entremont, Robert Atmospheric and Environmental Research, Inc. Mitchell, David Desert Research Institute Category: Cloud Properties Our project has focused on using satellite- and ground-based passive thermal infrared radiance observations to retrieve cirrus cloud properties, most importantly ice water path (IWP), effective particle size (Deff), and visible extinction optical thickness (tau). During this past year we began comparing our cirrus retrieval results with aircraft observations at the ARM CART site, and we are participating in a summary intercomparison study with other retrieval algorithms as a member of the high-clouds working group. Our passive-infrared retrieval scheme, based on different wavelength
heated by the sun, produces rising columns of air in which the moisture condenses into tall fleecy white clouds At night, when the sky is clear, the earth cools to give those...
Cloud properties derived from two lidars over the ARM SGP site
[1] Active remote sensors such as lidars or radars can be used with other data to quantify the cloud properties at regional scale and at global scale (Dupont et al., 2009). Relative to radar, lidar remote sensing is sensitive to very thin and high clouds but has a significant limitation due to signal attenuation in the ability to precisely quantify the properties of clouds with a 20 cloud optical thickness larger than 3. In this study, 10-years of backscatter lidar signal data are analysed by a unique algorithm called STRucture of ATmosphere (STRAT, Morille et al., 2007). We apply the STRAT algorithm to data from both the collocated Micropulse lidar (MPL) and a Raman lidar (RL) at the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site between 1998 and 2009. Raw backscatter lidar signal is processed and 25 corrections for detector deadtime, afterpulse, and overlap are applied. (Campbell et al.) The cloud properties for all levels of clouds are derived and distributions of cloud base height (CBH), top height (CTH), physical cloud thickness (CT), and optical thickness (COT) from local statistics are compared. The goal of this study is (1) to establish a climatology of macrophysical and optical properties for all levels of clouds observed over the ARM SGP site 30 and (2) to estimate the discrepancies induced by the two remote sensing systems (pulse energy, sampling, resolution, etc.). Our first results tend to show that the MPLs, which are the primary ARM lidars, have a distinctly limited range where all of these cloud properties are detectable, especially cloud top and cloud thickness, but even actual cloud base especially during summer daytime period. According to the comparisons between RL and MPL, almost 50% of situations show a signal to noise ratio too low (smaller than 3) for the MPL in order to detect clouds higher than 7km during daytime period in summer. Consequently, the MPLderived annual cycle of cirrus cloud base (top) altitude is biased low, especially for daylight periods, compared with those derived from the RL data, which detects 5 cloud base ranging from 7.5 km in winter to 9.5 km in summer (and tops ranging from 8.6 to 10.5 km). The optically thickest cirrus clouds (COT>0.3) reach 50% of the total population for the Raman lidar and only 20% for the Micropulse lidar due to the difference of pulse energy and the effect of solar irradiance contamination. A complementary study using the cloud fraction 10 derived from the Micropulse lidar for clouds below 5 km and from the Raman lidar for cloud above 5 km allows for better estimation of the total cloud fraction between the ground and the top of the atmosphere. This study presents the diurnal cycle of cloud fraction for each season in comparisons with the Long et al. (2006) cloud fraction calculation derived from radiative flux analysis.
Dupont, Jean-Charles; Haeffelin, Martial; Morille, Y.; Comstock, Jennifer M.; Flynn, Connor J.; Long, Charles N.; Sivaraman, Chitra; Newsom, Rob K.
Cloud Properties Derived from Visible and Near-infrared Reflectance in the
Cloud Properties Derived from Visible and Near-infrared Reflectance in the Cloud Properties Derived from Visible and Near-infrared Reflectance in the Presence of Aerosols Hofmann, Odele University of Colorado at Boulder Pilewskie, Peter University of Colorado Gore, Warren NASA Ames Research Center Russell, Phil NASA Ames Research Center Livingston, John SRI International Redemann, Jens BAERI/NASA Ames Research Center Bergstrom, Robert Bay Area Environmental Research Institute Platnick, Steven NASA-GSFC Daniel, John NOAA Aeronomy Laboratory Category: Cloud Properties The New England Air Quality Study - Intercontinental Transport and Chemical Transformation (NEAQS-ITCT) experiment conducted in July-August 2004 included objectives on the effects of urban-industrial pollution aerosols on cloud radiative properties, the so-called indirect effect. Measurements
A GCM Parameterization for the Shortwave Radiative Properties of Water Clouds
A new parameterization is presented for the shortwave radiative properties of water clouds, which is fast enough to be included in general circulation models (GCMs). It employs the simple relationships found by Slingo and Schrecker for the ...
A. Slingo
Implementation of the Daytime Cloud Optical and Microphysical Properties Algorithm (DCOMP) in PATMOS-x
This paper describes the daytime cloud optical and microphysical properties (DCOMP) retrieval for the Pathfinder Atmosphere�s Extended (PATMOS-x) climate dataset. Within PATMOS-x, DCOMP is applied to observations from the Advanced Very High ...
Andi Walther; Andrew K. Heidinger
An Accurate Parameterization of the Solar Radiative Properties of Cirrus Clouds for Climate Models
An accurate parameterization of the solar radiative properties of cirrus clouds is developed based on improved light scattering calculations. Here 28 ice crystal size distributions from in situ aircraft observations in both tropical and ...
Qiang Fu
Microwave Radiative Transfer through Clouds Composed of Realistically Shaped Ice Crystals. Part I. Single Scattering Properties
This paper presents the results of a detailed study of the microwave single scattering properties of ice crystals expected in cirrus clouds. The discrete dipole approximation is used to compute scattering quantities of particles ranging in size ...
K. Franklin Evans; Graeme L. Stephens
Radiative Impacts of Free-Tropospheric Clouds on the Properties of Marine Stratocumulus
Observations from multiple satellites and large-eddy simulations (LESs) from the Regional Atmospheric Modeling System (RAMS) are used to determine the extent to which free-tropospheric clouds (FTCs) affect the properties of stratocumulus. ...
Matthew W. Christensen; Gustavo G. Carri�; Graeme L. Stephens; William R. Cotton
On the Identification of the Large-Scale Properties of Tropical Convection using Cloud Regimes
The use of cloud regimes in identifying tropical convection and the associated large-scale atmospheric properties is investigated. The regimes are derived by applying cluster analysis to satellite retrievals of daytime-averaged frequency ...
Jackson Tan; Christian Jakob; Todd P. Lane
A Simple Method to Retrieve Cloud Properties from Atmospheric Transmittance and Liquid Water Column Measurements
A deeper knowledge of the effects and interactions of clouds in the climatic system requires developing both satellite and ground-based methods to assess their optical properties. A simple method based on a parameterized inversion of a radiative ...
Salvador Matamoros; Josep-Abel Gonz�lez; Josep Calb�
Cloud Properties and Their Seasonal and Diurnal Variability from TOVS Path-B
Eight years of cloud properties retrieved from Television Infrared Observation Satellite-N (TIROS-N) Observational Vertical Sounder (TOVS) observations aboard the NOAA polar orbiting satellites are presented. The relatively high spectral ...
C. J. Stubenrauch; A. Ch�din; G. R�del; N. A. Scott; S. Serrar
Sensitivity of Simulated Global Climate to Perturbations in Low Cloud Microphysical Properties. Part II: Spatially Localized Perturbations
The sensitivity of the global climate to spatially localized (20��70�N) perturbations in the microphysical properties of low clouds is investigated using a general circulation model coupled to a mixed layer ocean with fixed cloud distributions. ...
C-T. Chen; V. Ramaswamy
Long-term impacts of aerosols on vertical development of cloud and precipitation
Aerosols alter cloud density and the radiative balance of the atmosphere. This leads to changes in cloud microphysics and atmospheric stability, which can either suppress or foster the development of clouds and precipitation. The net effect is largely unknown, but depends on meteorological conditions and aerosol properties. Here, we examine the long-term impact of aerosols on the vertical development of clouds and rainfall frequencies, using a 10-year dataset of aerosol, cloud and meteorological variables collected in the Southern Great Plains in the United States. We show that cloud-top height and thickness increase with aerosol concentration measured near the ground in mixed-phase clouds-which contain both liquid water and ice-that have a warm, low base. We attribute the effect, which is most significant in summer, to an aerosol-induced invigoration of upward winds. In contrast, we find no change in cloud-top height and precipitation with aerosol concentration in clouds with no ice or cool bases. We further show that precipitation frequency and rain rate are altered by aerosols. Rain increases with aerosol concentration in deep clouds that have a high liquid-water content, but declines in clouds that have a low liquid-water content. Simulations using a cloud-resolving model confirm these observations. Our findings provide unprecedented insights of the long-term net impacts of aerosols on clouds and precipitation.
Li Z.; Liu Y.; Niu, F.; Fan, J.; Rosenfeld, D.; Ding, Y.
Radiative Properties of Cirrus Clouds in the Infrared Region
A multiple-scattering radiative transfer model is employed to evaluate the 11 ?m and the broad-band infrared (IR) fluxes, cooling rates and emittances in model cirrus clouds for a number of standard vertical atmospheric profiles of temperature ...
Graeme L. Stephens
Cloud Activating Properties of Aerosol Observed during CELTIC
Measurements of aerosol size distribution, chemical composition, and cloud condensation nuclei (CCN) concentration were performed during the Chemical Emission, Loss, Transformation, and Interactions with Canopies (CELTIC) field program at Duke ...
Craig A. Stroud; Athanasios Nenes; Jose L. Jimenez; Peter F. DeCarlo; J. Alex Huffman; Roelof Bruintjes; Eiko Nemitz; Alice E. Delia; Darin W. Toohey; Alex B. Guenther; Sreela Nandi
Radiative Properties of Cirrus Clouds Derived from Surface Interferometric Measurements
Beam transmittance, emittance, reflectance, and outgoing radiance are inferred from interferometric measurements in the infrared window region for 14 temperate continental and 12 subtropical cirrus cloud cash observed during FIRE II at Parsons, ...
Gordon H. Beck; John M. Davis; S. K. Cox
Retrieving Properties of Thin Clouds from Solar Aureole Measurements
This paper describes a newly designed Sun and Aureole Measurement (SAM) aureolegraph and the first results obtained with this instrument. SAM measurements of solar aureoles produced by cirrus and cumulus clouds were taken at the Atmospheric ...
J. G. DeVore; A. T. Stair; A. LePage; D. Rall; J. Atkinson; D. Villanucci; S. A. Rappaport; P. C. Joss; R. A. McClatchey
Evaluation of Tropical Cirrus Cloud Properties and Dynamical...
through the TTL into the stratosphere. The ability of large-scale models to correctly forecast tropical cirrus occurrence is important in predicting the role of these clouds on...
Retrieval of Cloud Microphysical Properties from MODIS and AIRS
The Moderate Resolution Imaging Spectroradiometer (MODIS) and the Atmospheric Infrared Sounder (AIRS) measurements from the NASA Earth Observing System Aqua satellite enable global monitoring of the distribution of clouds during day and night. ...
Jun Li; Hung-Lung Huang; Chian-Yi Liu; Ping Yang; Timothy J. Schmit; Heli Wei; Elisabeth Weisz; Li Guan; W. Paul Menzel
Factors influencing the microphysics and radiative properties of liquid-dominated Arctic clouds: insight from observations of aerosol and clouds during ISDAC
Aircraft measurements during the Indirect and Semi-Direct Aerosol Campaign (ISDAC) in April 2008 are used to investigate aerosol indirect effects in Arctic clouds. Two aerosol-cloud regimes are considered in this analysis: single-layer stratocumulus cloud with below-cloud aerosol concentrations (N{sub a}) below 300 cm{sup -3} on April 8 and April 26-27 (clean cases); and inhomogeneous layered cloud with N{sub a} > 500 cm{sup -3} below cloud base on April 19-20, concurrent with a biomass burning episode (polluted cases). Vertical profiles through cloud in each regime are used to determine average cloud microphysical and optical properties. Positive correlations between the cloud droplet effective radius (Re) and cloud optical depth ({tau}) are observed for both clean and polluted cases, which are characteristic of optically-thin, non-precipitating clouds. Average Re values for each case are {approx} 6.2 {mu}m, despite significantly higher droplet number concentrations (Nd) in the polluted cases. The apparent independence of Re and Nd simplifies the description of indirect effects, such that {tau} and the cloud albedo (A) can be described by relatively simple functions of the cloud liquid water path. Adiabatic cloud parcel model simulations show that the marked differences in Na between the regimes account largely for differences in droplet activation, but that the properties of precursor aerosol also play a role, particularly for polluted cases where competition for vapour amongst the more numerous particles limits activation to larger and/or more hygroscopic particles. The similarity of Re for clean and polluted cases is attributed to compensating droplet growth processes for different initial droplet size distributions.
Earle, Michael; Liu, Peter S.; Strapp, J. Walter; Zelenyuk, Alla; Imre, D.; McFarquhar, Greg; Shantz, Nicole C.; Leaitch, W. R.
Study of Ice Cloud Properties from Synergetic Use of Satellite Observations and Modeling Capabilities
The dissertation first investigates the single-scattering properties of inhomogeneous ice crystals containing air bubbles. Specifically, a combination of the ray-tracing technique and the Monte Carlo method is used to simulate the scattering of light by randomly oriented large hexagonal ice crystals containing spherical or spheroidal air bubbles. The effect of the air bubbles within ice crystals is to smooth the phase functions, diminish the 22� and 46� halo peaks, and reduce the backscatter in comparison with the case of bubble-free ice crystals. Cloud reflectance look-up tables were generated at the wavelengths of 0.65 ?m and 2.13 ?m to examine the impact of accounting for air bubbles in ice crystal morphology on the retrieval of ice cloud optical thickness and effective particle size. To investigate the effect of the representation of aggregates on electromagnetic scattering calculations, an algorithm is developed to efficiently specify the geometries of aggregates and to compute some of their geometric parameters such as the projected area. Based on in situ observations, aggregates are defined as clusters of hexagonal plates with a chain-like overall shape. An aggregate model is developed with 10 ensemble members, each consisting of between 4-12 hexagonal plates. The scattering properties of an individual aggregate ice particle are computed using the discrete dipole approximation or an Improved Geometric Optics Method, depending upon the size parameter. The aggregate model provides an accurate and computationally efficient way to represent all aggregates occurring within ice clouds. We developed an algorithm to determine an appropriate ice cloud model for application to satellite-based retrieval of ice cloud properties. Collocated Moderate Resolution Imaging Spectroradiometer and Multi-angle Imaging SpectroRadiometer (MISR) data are used to retrieve the optical thicknesses of ice clouds as a function of scattering angle in the nine MISR viewing directions. The difference between cloud optical thickness and its averaged value over the nine viewing angles can be used to validate the ice cloud models. Using the data obtained on 2 July 2009, an appropriate ice cloud model is determined. With the presence of all the uncertainties in the current operational satellite-based retrievals of ice cloud properties, this ice cloud model has excellent performance in terms of consistency in cloud property retrievals with the nine MISR viewing angles.
Xie, Yu
Global ice cloud observations: radiative properties and statistics from moderate-resolution imaging spectroradiometer measurements
Ice clouds occur quite frequently, yet so much about these clouds is unknown. In recent years, numerous investigations and field campaigns have been focused on the study of ice clouds, all with the ultimate goal of gaining a better understanding of microphysical and optical properties, as well as determining the radiative impact. Perhaps one of the most recognized instruments used for such research is the Moderate-resolution Imaging Spectroradiometer (MODIS), carried aboard the NASA EOS satellites Terra and Aqua. The present research aims to support ongoing efforts in the field of ice cloud research by use of observations obtained from Terra and Aqua MODIS. First, a technique is developed to infer ice cloud optical depth from the MODIS cirrus reflectance parameter. This technique is based on a previous method developed by Meyer et al. (2004). The applicability of the algorithm is demonstrated with retrievals from level-2 and -3 MODIS data. The technique is also evaluated with the operational MODIS cloud retrieval product and a method based on airborne ice cloud observations. From this technique, an archive of daily optical depth retrievals is constructed. Using simple statistics, the global spatial and temporal distributions of ice clouds are determined. Research has found that Aqua MODIS observes more frequent ice clouds and larger optical depths and ice water paths than does Terra MODIS. Finally, an analysis of the time series of daily optical depth values revealed that ice clouds at high latitudes, which are most likely associated with synoptic scale weather sytems, persist long enough to move with the upper level winds. Tropical ice clouds, however, dissipate more rapidly, and are in all likelihood associated with deep convective cells.
Meyer, Kerry Glynne
Validation of Cloud Properties Derived from GOES-9 Over the ARM TWP Region
Cloud Properties Derived from Cloud Properties Derived from GOES-9 Over the ARM TWP Region M. M. Khaiyer, M. L. Nordeen, D. R. Doelling, and V. Chakrapani Analytical Services and Materials, Inc. Hampton, Virginia P. Minnis and W. L. Smith, Jr. Atmospheric Sciences National Aeronautic and Space Administration Langley Research Center Hampton, Virginia Introduction Satellite data are essential for monitoring clouds and radiative fluxes where ground-based instruments are unavailable. On April 24, 2003, the ninth geostationary operational environmental satellite (GOES-9) began operational coverage of the Tropical Western Pacific (TWP), replacing the failing fifth geostationary meteorological satellite (GMS-5). The GOES-9 imager provides the opportunity for enhanced monitoring of clouds and radiation over the TWP because it has better spatial resolution and
Derivation of Seasonal Cloud Properties at ARM-NSA from Multispectral MODIS Data
Derivation of Seasonal Cloud Properties at ARM-NSA Derivation of Seasonal Cloud Properties at ARM-NSA from Multispectral MODIS Data D. A. Spangenberg Analytical Services and Materials, Inc. Hampton, Virginia P. Minnis National Aeronautics and Space Administration Langley Research Center Hampton, Virginia T. Uttal National Oceanic and Atmospheric Administration Environmental Technology Laboratory Boulder, Colorado Q. Z. Trepte and S. S.-Mack Science Applications International Corporation Hampton, Virginia Introduction Improving climate model predictions over earth's Polar Regions requires a complete knowledge of polar cloud microphysics. Over the Arctic, there is minimal contrast between the clouds and background snow surface observed in satellite data, especially for visible wavelengths. This makes it difficult to
Observed and Simulated Cirrus Cloud Properties at the SGP CART Site
and Simulated Cirrus Cloud Properties and Simulated Cirrus Cloud Properties at the SGP CART Site A. D. Del Genio and A. B. Wolf National Aeronautics and Space Administration Goddard Institute for Space Studies New York, New York G. G. Mace University of Utah Salt Lake City, Utah Introduction Despite their potential importance in a long-term climate change, less is known about cirrus clouds than most other cloud types, for a variety of reasons (Del Genio 2001) including: (1) the difficulty of remotely sensing ice water content (IWC), (2) uncertainty in the identities of ice nuclei and the relative importance of different nucleation processes, (3) significant variations in depth and optical thickness caused by formation and sedimentation of large particles, and (4) our relatively poor documentation of
A Balloon-Borne Continuous Cloud Particle Replicator for Measuring Vertical Profiles of Cloud Microphysical Properties: Instrument Design, Performance, and Collection Efficiency Analysis
The performance of a balloon-borne Formvar replicator that measures continuous profiles of cloud microphysical properties is investigated. The replicator measures the small particles (<100-?m diameter) that are undetectable or poorly resolved by ...
Larry M. Miloshevich; Andrew J. Heymsfield
A Climatology of Midlatitude Continental Clouds from the ARM SGP Central Facility: Part I: Low-Level Cloud Macrophysical, Microphysical, and Radiative Properties
A record of single-layer and overcast low cloud (stratus) properties has been generated using approximately 4000 h of data collected from January 1997 to December 2002 at the Atmospheric Radiation Measurement (ARM) Southern Great Plains Central ...
Xiquan Dong; Patrick Minnis; Baike Xi
The Microbase Value-Added Product: A Baseline Retrieval of Cloud Microphysical Properties
This report describes the Atmospheric Radiation Measurement (ARM) Climate Research Facility baseline cloud microphysical properties (MICROBASE) value-added product (VAP). MICROBASE uses a combination of millimeter-wavelength cloud radar, microwave radiometer, and radiosonde observations to estimate the vertical profiles of the primary microphysical parameters of clouds including the liquid/ice water content and liquid/ice cloud particle effective radius. MICROBASE is a baseline algorithm designed to apply to most conditions and locations using a single set of parameterizations and a simple determination of water phase based on temperature. This document provides the user of this product with guidelines to assist in determining the accuracy of the product under certain conditions. Quality control flags are designed to identify outliers and indicate instances where the retrieval assumptions may not be met. The overall methodology is described in this report through a detailed description of the input variables, algorithms, and output products.
Dunn, M; Johnson, K; Jensen, M
Evaluating cloud retrieval algorithms with the ARM BBHRP framework
Climate and weather prediction models require accurate calculations of vertical profiles of radiative heating. Although heating rate calculations cannot be directly validated due to the lack of corresponding observations, surface and top-of-atmosphere measurements can indirectly establish the quality of computed heating rates through validation of the calculated irradiances at the atmospheric boundaries. The ARM Broadband Heating Rate Profile (BBHRP) project, a collaboration of all the working groups in the program, was designed with these heating rate validations as a key objective. Given the large dependence of radiative heating rates on cloud properties, a critical component of BBHRP radiative closure analyses has been the evaluation of cloud microphysical retrieval algorithms. This evaluation is an important step in establishing the necessary confidence in the continuous profiles of computed radiative heating rates produced by BBHRP at the ARM Climate Research Facility (ACRF) sites that are needed for modeling studies. This poster details the continued effort to evaluate cloud property retrieval algorithms within the BBHRP framework, a key focus of the project this year. A requirement for the computation of accurate heating rate profiles is a robust cloud microphysical product that captures the occurrence, height, and phase of clouds above each ACRF site. Various approaches to retrieve the microphysical properties of liquid, ice, and mixed-phase clouds have been processed in BBHRP for the ACRF Southern Great Plains (SGP) and the North Slope of Alaska (NSA) sites. These retrieval methods span a range of assumptions concerning the parameterization of cloud location, particle density, size, shape, and involve different measurement sources. We will present the radiative closure results from several different retrieval approaches for the SGP site, including those from Microbase, the current 'reference' retrieval approach in BBHRP. At the NSA, mixed-phase clouds and cloud with a low optical depth are prevalent; the radiative closure studies using Microbase demonstrated significant residuals. As an alternative to Microbase at NSA, the Shupe-Turner cloud property retrieval algorithm, aimed at improving the partitioning of cloud phase and incorporating more constrained, conditional microphysics retrievals, also has been evaluated using the BBHRP data set.
Mlawer,E.; Dunn,M.; Mlawer, E.; Shippert, T.; Troyan, D.; Johnson, K. L.; Miller, M. A.; Delamere, J.; Turner, D. D.; Jensen, M. P.; Flynn, C.; Shupe, M.; Comstock, J.; Long, C. N.; Clough, S. T.; Sivaraman, C.; Khaiyer, M.; Xie, S.; Rutan, D.; Minnis, P.
Solar differential rotation and properties of magnetic clouds
The most geoeffective solar drivers are magnetic clouds - a subclass of coronal mass ejections (CME's) distinguished by the smooth rotation of the magnetic field inside the structure. The portion of CME's that are magnetic clouds is maximum at sunspot minimum and mimimum at sunspot maximum. This portion is determined by the amount of helicity carried away by CME's which in turn depends on the amount of helicity transferred from the solar interior to the surface, and on the surface differential rotation. The latter can increase or reduce, or even reverse the twist of emerging magnetic flux tubes, thus increasing or reducing the helicity in the corona, or leading to the violation of the hemispheric helicity rule, respectively. We investigate the CME's associated with the major geomagnetic storms in the last solar cycle whose solar sources have been identified, and find that in 10 out of 12 cases of violation of the hemispheric helicity rule or of highly geoeffective CME's with no magnetic field rotation, they o...
Georgieva, K; Gavruseva, E; Javaraiah, J
The most geoeffective solar drivers are magnetic clouds - a subclass of coronal mass ejections (CME's) distinguished by the smooth rotation of the magnetic field inside the structure. The portion of CME's that are magnetic clouds is maximum at sunspot minimum and mimimum at sunspot maximum. This portion is determined by the amount of helicity carried away by CME's which in turn depends on the amount of helicity transferred from the solar interior to the surface, and on the surface differential rotation. The latter can increase or reduce, or even reverse the twist of emerging magnetic flux tubes, thus increasing or reducing the helicity in the corona, or leading to the violation of the hemispheric helicity rule, respectively. We investigate the CME's associated with the major geomagnetic storms in the last solar cycle whose solar sources have been identified, and find that in 10 out of 12 cases of violation of the hemispheric helicity rule or of highly geoeffective CME's with no magnetic field rotation, they originate from regions with "anti-solar" type of surface differential rotation.
K. Georgieva; B. Kirov; E. Gavruseva; J. Javaraiah
Homogeneous Nucleation Rate for Highly Supercooled Cirrus Cloud Droplets
A mixed-phase hydrometer growth model has been applied to determining the nucleation mode and rate responsible for the glaciation of a highly supercooled liquid cloud studied jointly by ground-based polarization lidar and aircraft in situ probes. ...
Kenneth Sassen; Gregory C. Dodd
Computing and Partitioning Cloud Feedbacks Using Cloud Property Histograms. Part II: Attribution to Changes in Cloud Amount, Altitude, and Optical Depth
Cloud radiative kernels and histograms of cloud fraction, both as functions of cloud-top pressure and optical depth, are used to quantify cloud amount, altitude, and optical depth feedbacks. The analysis is applied to doubled-CO2 simulations from ...
Rapid Daytime Estimation of Cloud Properties over a Large Area from Radiance Distributions
An algorithm is developed to rapidly estimate cloud properties for a large area from daytime imager data. In this context, a large area refers to a grid cell composed of many imager pixels. The algorithm assumes a gamma distribution to model the ...
Andrew K. Heidinger
Effect of Cavities on the Optical Properties of Bullet Rosettes: Implications for Active and Passive Remote Sensing of Ice Cloud Properties
.e., the scattering phase matrix, extinction cross section, and single-scattering albedo) of nonspherical ice the parameterization of the bulk radiative properties of ice clouds, which is a Corresponding author address: Dr. Ping and Passive Remote Sensing of Ice Cloud Properties PING YANG,* ZHIBO ZHANG,* GEORGE W. KATTAWAR, STEPHEN G
Baum, Bryan A.
Quantifying the Impact of Dust on Heterogeneous Ice Generation in Midlevel Supercooled Stratiform Clouds
Dust aerosols have been regarded as effective ice nuclei (IN), but large uncertainties regarding their efficiencies remain. Here, four years of collocated CALIPSO and CloudSat measurements are used to quantify the impact of dust on heterogeneous ice generation in midlevel supercooled stratiform clouds (MSSCs) over the �dust belt�. The results show that the dusty MSSCs have an up to 20% higher mixed-phase cloud occurrence, up to 8 dBZ higher mean maximum Ze (Ze_max), and up to 11.5 g/m2 higher ice water path (IWP) than similar MSSCs under background aerosol conditions. Assuming similar ice growth and fallout history in similar MSSCs, the significant differences in Ze_max between dusty and non-dusty MSSCs reflect ice particle number concentration differences. Therefore, observed Ze_max differences indicate that dust could enhance ice particle concentration in MSSCs by a factor of 2 to 6 at temperatures colder than ?12�C. The enhancements are strongly dependent on the cloud top temperature, large dust particle concentration and chemical compositions. These results imply an important role of dust particles in modifying mixed-phase cloud properties globally.
Zhang, Damao; Wang, Zhien; Heymsfield, Andrew J.; Fan, Jiwen; Liu, Dong; Zhao, Ming
Evaluating Global Aerosol Models and Aerosol and Water Vapor Properties Near Clouds
Project goals: (1) Use the routine surface and airborne measurements at the ARM SGP site, and the routine surface measurements at the NSA site, to continue our evaluations of model aerosol simulations; (2) Determine the degree to which the Raman lidar measurements of water vapor and aerosol scattering and extinction can be used to remotely characterize the aerosol humidification factor; (3) Use the high temporal resolution CARL data to examine how aerosol properties vary near clouds; and (4) Use the high temporal resolution CARL and Atmospheric Emitted Radiance Interferometer (AERI) data to quantify entrainment in optically thin continental cumulus clouds.
Richard A. Ferrare; David D. Turner
A New Double-Moment Microphysics Parameterization for Application in Cloud and Climate Models. Part II: Single-Column Modeling of Arctic Clouds
of the arctic bound- ary layer, the presence of leads (cracks) in the sea ice surface, the persistence of mixed-phaseA New Double-Moment Microphysics Parameterization for Application in Cloud and Climate Models. Part- dicted cloud boundaries and total cloud fraction compare reasonably well with observations. Cloud phase
Zuidema, Paquita
Use of In Situ Observations to Characterize Cloud Microphysical and Radiative Properties: Application to Climate Studies
Use of In Situ Observations to Characterize Use of In Situ Observations to Characterize Cloud Microphysical and Radiative Properties: Application to Climate Studies G. M. McFarquhar and T. Nousiainen Department of Atmospheric Sciences University of Illinois Urbana, Illinois M. S. Timlin, S. F. Iacobellis, and R. C. J. Somerville Scripps Institution of Oceanography La Jolla, California Introduction Cloud radiative feedback is the most important effect determining climate response to human activity. Ice clouds reflect solar radiation and absorb thermal emission from the ground and the lower atmosphere and emit infrared radiation to space. The representation of these processes in models affects future climate predictions and there is much uncertainty in the representation of these processes. The size and
In Situ Observations of the Microphysical Properties of Wave, Cirrus, and Anvil Clouds. Part II: Cirrus Clouds
A Learjet research aircraft was used to collect microphysical data, including cloud particle imager (CPI) measurements of ice particle size and shape, in 22 midlatitude cirrus clouds. The dataset was collected while the aircraft flew 104 ...
R. Paul Lawson; Brad Baker; Bryan Pilson; Qixu Mo
Effects of Aerosols on the Radiative Properties of Clouds
The influence of anthropogenic aerosols, in the form of ship exhaust effluent, on the microphysics and radiative properties of marine stratocumulus is studied using data gathered from the U.K. Met. Office C-130 and the University of Washington C-...
Jonathan P. Taylor; Martin D. Glew; James A. Coakley Jr.; William R. Tahnk; Steven Platnick; Peter V. Hobbs; Ronald J. Ferek
Investigation of the optical and cloud forming properties of pollution, biomass burning, and mineral dust aerosols
This dissertation describes the use of measured aerosol size distributions and size-resolved hygroscopic growth to examine the physical and chemical properties of several particle classes. The primary objective of this work was to investigate the optical and cloud forming properties of a range of ambient aerosol types measured in a number of different locations. The tool used for most of these analyses is a differential mobility analyzer / tandem differential mobility analyzer (DMA / TDMA) system developed in our research group. To collect the data described in two of the chapters of this dissertation, an aircraft-based version of the DMA / TDMA was deployed to Japan and California. The data described in two other chapters were conveniently collected during a period when the aerosol of interest came to us. The unique aspect of this analysis is the use of these data to isolate the size distributions of distinct aerosol types in order to quantify their optical and cloud forming properties. I used collected data during the Asian Aerosol Characterization Experiment (ACE-Asia) to examine the composition and homogeneity of a complex aerosol generated in the deserts and urban regions of China and other Asian countries. An aircraft-based TDMA was used for the first time during this campaign to examine the size-resolved hygroscopic properties of the aerosol. The Asian Dust Above Monterey (ADAM-2003) study was designed both to evaluate the degree to which models can predict the long-range transport of Asian dust, and to examine the physical and optical properties of that aged dust upon reaching the California coast. Aerosol size distributions and hygroscopic growth were measured in College Station, Texas to investigate the cloud nucleating and optical properties of a biomass burning aerosol generated from fires on the Yucatan Peninsula. Measured aerosol size distributions and size-resolved hygroscopicity and volatility were used to infer critical supersaturation distributions of the distinct particle types that were observed during this period. The predicted cloud condensation nuclei concentrations were used in a cloud model to determine the impact of the different aerosol types on the expected cloud droplet concentration. RH-dependent aerosol extinction coefficients were also calculated.
Lee, Yong Seob
Computation of Domain-Averaged Irradiance with a Simple Two-Stream Radiative Transfer Model Including Vertical Cloud Property Correlations
Computation of Domain-Averaged Irradiance Computation of Domain-Averaged Irradiance with a Simple Two-Stream Radiative Transfer Model Including Vertical Cloud Property Correlations S. Kato Center for Atmospheric Sciences Hampton University Hampton, Virginia Introduction Recent development of remote sensing instruments by Atmospheric Radiation Measurement (ARM?) Program provides information of spatial and temporal variability of cloud structures. However it is not clear what cloud properties are required to express complicated cloud fields in a realistic way and how to use them in a relatively simple one-dimensional (1D) radiative transfer model to compute the domain averaged irradiance. To address this issue, a simple shortwave radiative transfer model that can treat the vertical cloud optical property correlation is developed. The model is based on the gamma-weighted
Simulating mixed-phase Arctic stratus clouds: Sensitivity to ice initiation mechanisms
M. : Role of a parameterized ice-phase micro- physics in anconcentration (N i ) for ice phase in experiments with icei L ?1 Table 8. Composite ice phase effective radius (R ei )
parameterization in BRM scheme accounts for two general mech- anisms distinguishable according to the involvement of liquid phase in the ice
Mixed-Phase Arctic Cloud Experiment (M-PACE): the Field Campaign
DOE Data Explorer (OSTI)
This case study presents data from 27 Sep 2004 to 22 Oct 2004 and covers a region from 65N to 75N latitude and from 160W to 145W longitude.
- and mixed-phase hydrometeors (cloud ice, snow, graupel, and hail) are often excluded or limited due of interactions of ice-phase cloud hydrometeors with volatile chemicals have found that they may significantly. 2. ICE- AND MIXED-PHASE CHEMISTRY 2.1 Gas-Solid Transfer Gas-phase chemical species can diffuse
Stuart, Amy L.
Wide-Angle Imaging Lidar Deployment at the ARM Southern Great Plains Site: Intercomparison of Cloud Property Retrievals
The Wide-Angle Imaging Lidar (WAIL), a new instrument that measures cloud optical and geometrical properties by means of off-beam lidar returns, was deployed as part of a multi-instrument campaign to probe a cloud field at the Atmospheric ...
Igor N. Polonsky; Steven P. Love; Anthony B. Davis
DRAFT, Revised June 2012 Aerosol cloud-mediated radiative forcing: highly uncertain and
clouds is even lower than for the shallow clouds, as mixed phase and ice processes play an important role state of cloud and aerosol parameterizations, but intense research efforts aimed at improving. Respectively, the parameterization of these processes for GCMs is further away than for the low clouds
Daniel, Rosenfeld
Observational Constraints on the Cloud Thermodynamic Phase in Midlatitude Storms CATHERINE M. NAUD
in the ice versus the liquid phase. Early prognostic cloud water parameterizations for stratiform clouds supercooled liquid water gradually gives way to ice in the mixed-phase regions of clouds are still poorlyObservational Constraints on the Cloud Thermodynamic Phase in Midlatitude Storms CATHERINE M. NAUD
Interrelationships between Cloud Properties and Sea Surface Temperatures on Seasonal and Interannual Time Scales
Monthly means of selected variables of the 2.5� International Satellite Cloud Climatology Project (ISCCP) C2 total cloud cover (CC), cloud-top pressure (CTP), and cloud water (CW) are statistically related to sea surface temperature (SST). The ...
Bryan C. Weare
Measurements of Transformations in the Physical and Chemical Properties of Clouds Associated with Onshore Flow in Washington State
Preliminary measurements of several physical and chemical parameters associated with clouds in two cases of onshore flow over western Washington suggest that the physical and chemical properties of maritime, cloudy air passing over this region ...
Dean A. Hegg; Lawrence F. Radke; Peter V. Hobbs
Top-of-Atmosphere Albedo Estimation from Angular Distribution Models Using Scene Identification from Satellite Cloud Property Retrievals
The next generation of earth radiation budget satellite instruments will routinely merge estimates of global top-of-atmosphere radiative fluxes with cloud properties. This information will offer many new opportunities for validating radiative ...
Norman G. Loeb; Fr�d�ric Parol; Jean-Claude Buriez; Claudine Vanbauce
Properties of Northern Hemisphere Polar Stratospheric Clouds and Volcanic Aerosol in 1991/92 from UARS/ISAMS Satellite Measurements
Observations of polar stratospheric clouds by the Improved Stratospheric and Mesospheric Sounder (ISAMS) experiment on the Upper Atmospheric Research Satellite (UARS) have revealed new details of their global properties and behavior. These ...
F. W. Taylor; A. Lambert; R. G. Grainger; C. D. Rodgers; J. J. Remedios
A 3-Year Climatology of Cloud and Radiative Properties Derived from GOES-8 Data Over the Southern Great Plains
3-Year Climatology of Cloud and Radiative Properties 3-Year Climatology of Cloud and Radiative Properties Derived from GOES-8 Data Over the Southern Great Plains M. M. Khaiyer, A. D. Rapp, D. R. Doelling, and M. L. Nordeen Analytical Service and Materials, Inc. Hampton, Virginia P. Minnis, W. L. Smith, Jr., and L. Nguyen Atmospheric Sciences Division National Aeronautics and Space Administration Langley Research Center Hampton, Virginia Introduction While the various instruments maintained at the Atmospheric Radiation Measurement (ARM) Program Southern Great Plains (SGP) Central Facility (CF) provide detailed cloud and radiation measurements for a small area, satellite cloud property retrievals provide a means of examining the large-scale properties of the surrounding region over an extended period of time. Seasonal and inter-annual
Cirrus Cloud Properties and the Large-Scale Meteorological Environment: Relationships Derived from A-Train and NCEP�NCAR Reanalysis Data
Empirical knowledge of how cirrus cloud properties are coupled with the large-scale meteorological environment is a prerequisite for understanding the role of microphysical processes in the life cycle of cirrus cloud systems. Using active and ...
Elizabeth Berry; Gerald G. Mace
Comparison of CALIPSO-Like, LaRC, and MODIS Retrievals of Ice-Cloud Properties over SIRTA in France and Florida during CRYSTAL-FACE
This study compares cirrus-cloud properties and, in particular, particle effective radius retrieved by a Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO)-like method with two similar methods using Moderate-Resolution ...
M. Chiriaco; H. Chepfer; P. Minnis; M. Haeffelin; S. Platnick; D. Baumgardner; P. Dubuisson; M. McGill; V. No�l; J. Pelon; D. Spangenberg; S. Sun-Mack; G. Wind
Bullet rosette particles are common in ice clouds, and the bullets may often be hollow. Here the single-scattering properties of randomly oriented hollow bullet rosette ice particles are investigated. A bullet, which is an individual branch of a ...
Ping Yang; Zhibo Zhang; George W. Kattawar; Stephen G. Warren; Bryan A. Baum; Hung-Lung Huang; Yong X. Hu; David Winker; Jean Iaquinta
STORMVEX: The Storm Peak Lab Cloud Property Validation Experiment Science and Operations Plan
During the Storm Peak Lab Cloud Property Validation Experiment (STORMVEX), a substantial correlative data set of remote sensing observations and direct in situ measurements from fixed and airborne platforms will be created in a winter season, mountainous environment. This will be accomplished by combining mountaintop observations at Storm Peak Laboratory and the airborne National Science Foundation-supported Colorado Airborne Multi-Phase Cloud Study campaign with collocated measurements from the second ARM Mobile Facility (AMF2). We describe in this document the operational plans and motivating science for this experiment, which includes deployment of AMF2 to Steamboat Springs, Colorado. The intensive STORMVEX field phase will begin nominally on 1 November 2010 and extend to approximately early April 2011.
Mace, J; Matrosov, S; Shupe, M; Lawson, P; Hallar, G; McCubbin, I; Marchand, R; Orr, B; Coulter, R; Sedlacek, A; Avallone, L; Long, C
Posters Diagnostic Analysis of Cloud Radiative Properties R.C.J. Somerville and S. F. Iacobellis
1 1 Posters Diagnostic Analysis of Cloud Radiative Properties R.C.J. Somerville and S. F. Iacobellis Scripps Institution of Oceanography University of California, San Diego La Jolla, California Introduction A current dilemma of climate modeling is that general circulation model (GCM) results are extremely sensitive to parameterizations of certain poorly understood physical processes, most notably cloud-radiation interactions. As a result, models with different plausible parameterizations give very different results. Yet, we have no firm basis for knowing which parameterization is more nearly "correct." It is true that parameterizations are not the only shortcoming of GCMs. Our current ability to create models that will adequately simulate today's climate and predict its evolution
Testing ice microphysics parameterizations in the NCAR Community Atmospheric Model Version 3 using Tropical Warm Pool�International Cloud Experiment data
Cloud properties have been simulated with a new double-moment microphysics scheme under the framework of the single column version of NCAR CAM3. For comparisons, the same simulation was made with the standard single-moment microphysics scheme of CAM3. Results from both simulations were compared favorably with observations during the Tropical Warm Pool- International Cloud Experiment by US Department of Energy Atmospheric Radiation Program in terms of the temporal variation and vertical distribution of cloud fraction and cloud condensate. Major differences between the two simulations are in the magnitude and distribution of ice water content within the mixed-phase cloud during the monsoon period, though the total frozen water (snow plus ice) content is similar. The ice mass content in the mixed-phase cloud from the new scheme is larger than that from the standard scheme, and extends 2 km further downward, which are closer to observations. The dependence of the frozen water mass fraction in total condensate on temperature from the new scheme is also closer to available observations. Outgoing longwave radiation (OLR) at the top of the atmosphere (TOA) from the simulation with the new scheme is in general larger than that with the standard scheme, while the surface downward longwave radiation is similar. Sensitivity tests suggest that different treatments of the ice effective radius contribute significantly to the difference in the TOA OLR in addition to cloud water path. The deep convection process affects both TOA OLR and surface downward longwave radiation. The over-frequently-triggered deep convention process in the model is not the only mechanism for the excess middle and high level clouds. Further evaluation especially for ice cloud properties based on in-situ data is needed.
Wang, Weiguo; Liu, Xiaohong; Xie, Shaocheng; Boyle, James; McFarlane, Sally A.
Liquid-gas mixed phase in nuclear matter at finite temperature
We explore the geometrical structure of Liquid-gas (LG) mixed phase which is relevant to nuclear matter in the crust region of compact stars or supernovae. To get the equation of state (EOS) of the system, the Maxwell construction is found to be applicable to symmetric nuclear matter, where protons and neutrons behave simultaneously. For asymmetric nuclear matter, on the other hand, the phase equilibrium can be obtained by fully solving the Gibbs conditions since the components in the L and G phases are completely different. We also discuss the effects of surface and the Coulomb interaction on the mixed phase.
Toshiki Maruyama; Toshitaka Tatsumi
LIRAD Observations of Tropical Cirrus Clouds in MCTEX. Part II: Optical Properties and Base Cooling in Dissipating Storm Anvil Clouds
During the Maritime Continent Thunderstorm Experiment (MCTEX), several decaying storm anvils were observed. The anvil clouds exhibited typical patterns of fallout and decay over a number of hours of observation. The anvil bases were initially ...
C. M. R. Platt; R. T. Austin; S. A. Young; A. J. Heymsfield
The Impact of Giant Cloud Condensation Nuclei on Drizzle Formation in Stratocumulus: Implications for Cloud Radiative Properties
The impact of giant and ultragiant cloud condensation nuclei (>5-?m radius) on drizzle formation in stratocumuli is investigated within a number of modeling frameworks. These include a simple box model of collection, a trajectory ensemble model (...
Graham Feingold; William R. Cotton; Sonia M. Kreidenweis; Janel T. Davis
The 'Evaluating Global Aerosol Models and Aerosol and Water Vapor Properties Near Clouds' project focused extensively on the analysis and utilization of water vapor and aerosol profiles derived from the ARM Raman lidar at the Southern Great Plains ARM site. A wide range of different tasks were performed during this project, all of which improved quality of the data products derived from the lidar or advanced the understanding of atmospheric processes over the site. These activities included: upgrading the Raman lidar to improve its sensitivity; participating in field experiments to validate the lidar aerosol and water vapor retrievals; using the lidar aerosol profiles to evaluate the accuracy of the vertical distribution of aerosols in global aerosol model simulations; examining the correlation between relative humidity and aerosol extinction, and how these change, due to horizontal distance away from cumulus clouds; inferring boundary layer turbulence structure in convective boundary layers from the high-time-resolution lidar water vapor measurements; retrieving cumulus entrainment rates in boundary layer cumulus clouds; and participating in a field experiment that provided data to help validate both the entrainment rate retrievals and the turbulent profiles derived from lidar observations.
Turner, David, D.; Ferrare, Richard, A.
Exploration of the MODIS Cloud-Top Property Products for the Investigation of Equatorial Wave Systems
The Moderate Resolution Imaging Spectroradiometer (MODIS) observations provide an unprecedented opportunity for studying cloud macrophysical (cloud-top pressure, temperature, height, and phase), microphysical (effective particle size), and ...
Yue Li; Gerald R. North; Ping Yang; Bryan A. Baum
DRAFT, last update 5 January 2012 Aerosol cloud-mediated radiative forcing: highly uncertain and
phase and ice processes. Respectively, the parameterization of these processes for GCMs is further away and aerosol parameterizations, but intense research efforts aimed at improving the realism of cloud lower than for the shallow clouds, as the deep clouds are much more complicated, because mixed phase
Wood, Robert
The Mass Distribution and Assembly of the Milky Way from the Properties of the Magellanic Clouds
We present a new measurement of the mass of the Milky Way (MW) based on observed properties of its largest satellite galaxies, the Magellanic Clouds (MCs), and an assumed prior of a {Lambda}CDM universe. The large, high-resolution Bolshoi cosmological simulation of this universe provides a means to statistically sample the dynamical properties of bright satellite galaxies in a large population of dark matter halos. The observed properties of the MCs, including their circular velocity, distance from the center of the MW, and velocity within the MW halo, are used to evaluate the likelihood that a given halo would have each or all of these properties; the posterior probability distribution function (PDF) for any property of the MW system can thus be constructed. This method provides a constraint on the MW virial mass, 1.2{sup +0.7} - {sub 0.4}(stat.){sup +0.3} - {sub 0.3}(sys.) x 10{sup 12} M {circle_dot} (68% confidence), which is consistent with recent determinations that involve very different assumptions. In addition, we calculate the posterior PDF for the density profile of the MW and its satellite accretion history. Although typical satellites of 10{sup 12} M {circle_dot} halos are accreted over a wide range of epochs over the last 10 Gyr, we find a {approx}72% probability that the MCs were accreted within the last Gyr, and a 50% probability that they were accreted together.
Busha, Michael T.; /KIPAC, Menlo Park /Zurich U.; Marshall, Philip J.; /KIPAC, Menlo Park /Oxford U.; Wechsler, Risa H.; /KIPAC, Menlo Park /SLAC; Klypin, Anatoly; /New Mexico State U.; Primack, Joel; /UC, Santa Cruz, Phys. Dept.
We present a new measurement of the mass of the Milky Way (MW) based on observed properties of its largest satellite galaxies, the Magellanic Clouds (MCs), and an assumed prior of a {Lambda}CDM universe. The large, high-resolution Bolshoi cosmological simulation of this universe provides a means to statistically sample the dynamical properties of bright satellite galaxies in a large population of dark matter halos. The observed properties of the MCs, including their circular velocity, distance from the center of the MW, and velocity within the MW halo, are used to evaluate the likelihood that a given halo would have each or all of these properties; the posterior probability distribution function (PDF) for any property of the MW system can thus be constructed. This method provides a constraint on the MW virial mass, 1.2{sup +0.7}{sub -0.4} (stat.){sup +0.3}{sub -0.3} (sys.) Multiplication-Sign 10{sup 12} M{sub Sun} (68% confidence), which is consistent with recent determinations that involve very different assumptions. In addition, we calculate the posterior PDF for the density profile of the MW and its satellite accretion history. Although typical satellites of 10{sup 12} M{sub Sun} halos are accreted over a wide range of epochs over the last 10 Gyr, we find a {approx}72% probability that the MCs were accreted within the last Gyr, and a 50% probability that they were accreted together.
Busha, Michael T.; Marshall, Philip J.; Wechsler, Risa H. [Kavli Institute for Particle Astrophysics and Cosmology, Physics Department, Stanford University, Stanford, CA 94305 (United States); Klypin, Anatoly [Astronomy Department, New Mexico State University, Las Cruces, NM 88003 (United States); Primack, Joel, E-mail: email@example.com, E-mail: email@example.com, E-mail: firstname.lastname@example.com, E-mail: email@example.com, E-mail: email@example.com [Department of Physics, University of California, Santa Cruz, CA 95064 (United States)
Molecular Cloud Properties and CO Line Emission in z >~ 6 Galaxies
We explore molecular cloud properties and the physics of CO transition lines in z >~ 6 Lyman-break galaxies and predict their CO fluxes using an analytic formalism built from global models of star formation in high-redshift galaxies that minimizes our reliance on local observations. Our model includes a new approach to calculating the molecular gas fraction that takes the total gas density, the star formation rate, and the star formation efficiency in clouds as the principle inputs. This method agrees with chemical equilibrium calculations of the molecular fraction based on local chemistry if galaxies at z >~ 6 have metallicities in the range of 3--30 percent of solar. Such low metallicities in turn imply that much of the carbon in these systems exists in ionized form rather than as CO. Moreover, we find that CO transitions will typically be sub-thermally populated, especially those higher-order lines observable at high redshift with ALMA. Ultimately, we expect current facilities will not be able to observe t...
Mu�oz, Joseph A
DOE/SC-ARM-10-021 STORMVEX: The Storm Peak Lab Cloud Property Validation Experiment
1 1 STORMVEX: The Storm Peak Lab Cloud Property Validation Experiment Science and Operations Plan J Mace Principal Investigator S Matrosov B Orr M Shupe R Coulter P Lawson A Sedlacek G Hallar L Avallone I McCubbin C Long R Marchand September 2010 DISCLAIMER This report was prepared as an account of work sponsored by the U.S. Government. Neither the United States nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service
A Midlatitude Cirrus Cloud Climatology from the Facility for Atmospheric Remote Sensing. Part III: Radiative Properties
In Part III of a series of papers describing the extended time high-cloud observations from the University of Utah Facility for Atmospheric Remote Sensing (FARS) supporting the First International Satellite Cloud Climatology Project (ISCCP) ...
Kenneth Sassen; Jennifer M. Comstock
The Effects of In-Cloud Sulfate Production on Light-Scattering Properties of Continental Aerosol
Model calculations am presented for continental scenarios that demonstrate that the heterogeneity in the chemistry of different size cloud drops can have a significant impact on the amount of sulfate produced in cloud, its size distribution, and ...
Po-Fat Yuen; Dean A. Hegg; Timothy V. Larson
Cluster Analysis of Cloud Properties over the Southern European Mediterranean Area in Observations and a Model
This paper demonstrates how satellite observations of the cloudiness over a complex area such as the European Mediterranean area can be classified into distinct cloud regimes by application of a K-means clustering algorithm to pixel-level cloud ...
Fr�d�rique Ch�ruy; Filipe Aires
Size Distributions and Dynamical Properties of Shallow Cumulus Clouds from Aircraft Observations and Satellite Data
In this paper aircraft observations of shallow cumulus over Florida during the Small Cumulus Microphysics Study (SCMS) are analyzed. Size distributions of cloud fraction, mass flux, and in-cloud buoyancy flux are derived. These distributions ...
Stefaan M. A. Rodts; Peter G. Duynkerke; Harm J. J. Jonker
Clouds at Arctic Atmospheric Observatories. Part I: Occurrence and Macrophysical Properties
Cloud observations over the past decade from six Arctic atmospheric observatories are investigated to derive estimates of cloud occurrence fraction, vertical distribution, persistence in time, diurnal cycle, and boundary statistics. Each ...
Matthew D. Shupe; Von P. Walden; Edwin Eloranta; Taneil Uttal; James R. Campbell; Sandra M. Starkweather; Masataka Shiobara
Arctic Stratus Cloud Properties and Radiative Forcing Derived from Ground-Based Data Collected at Barrow, Alaska
A record of single-layer and overcast low-level Arctic stratus cloud properties has been generated using data collected from May to September 2000 at the Atmospheric Radiation Measurement (ARM) North Slope of Alaska (NSA) (71.3�N, 156.6�W) site ...
Xiquan Dong; Gerald G. Mace
Reply to Comments on ``Seasonal Variation of the Physical Properties of Marine Boundary Layer Clouds off the California Coast''
CloudSat and Cloud-Aerosol Lidar and Infrared Pathfinder Stellite Observations (CALIPSO). J. Geophys
Dispersion of Cloud Droplet Size Distributions, Cloud Parameterization...
National Laboratory Upton, New York Introduction Most studies of the effect of aerosols on cloud radiative properties have considered only changes in the cloud droplet...
Satellite and Surface Data Synergy for Developing a 3D Cloud Structure and Properties Characterization Over the ARM SGP. S...
Satellite and Surface Data Synergy for Developing Satellite and Surface Data Synergy for Developing a 3D Cloud Structure and Properties Characterization Over the ARM SGP Site Stage 1: Cloud Amounts, Optical Depths, and Cloud Heights Reconciliation I. Genkova and C. N. Long Pacific Northwest National Laboratory Richland, Washington P. W. Heck Analytical Services & Materials, Inc. Hampton, Virginia P. Minnis National Aeronautics and Space Administration Langley Research Center Hampton, Virginia Introduction One of the primary Atmospheric Radiation Measurement (ARM) Program objectives is to obtain measurements applicable to the development of models for better understanding of radiative processes in the atmosphere. We address this goal by building a three-dimensional (3D) characterization of the
Microwave radiative transfer in the mixed-phase regions of tropical rainfall
Current physically-based Radiative Transfer Model (RTM) algorithms for estimating oceanic rain use a very simplified hydrometeor profile that ignores the mixed-phase regions (Wilheit et al., 1977). However, to estimate hydrometeor profiles more reasonably in the tropical precipitation regions, understanding of the brightness temperature (Tb) variations in the mixed-phase regions is essential. Further, establishing physical assumptions for microwave radiative transfer in the mixed-phase regions is necessary for quantifying and minimizing the uncertainties in the rainfall retrieval. Consequently, the objective of this study was to quantify uncertainties and to achieve a solid basis for improvement of the current rainfall retrieval, which is based on an RTM. To accomplish this, we examined data taken by the Convair-580 aircraft during the KWAJEX (Kwajalein Experiment). In order to calculate radiative transfer, the AMMR (Airborne Multi-channel Microwave Radiometer) data were combined with radiosonde data and aircraft microphysics data. Analyses were performed for the stratiform and convective rainfall regions respectively. In stratiform precipitation with a bright band, the main concern was to examine the needed physical assumptions for describing the abrupt change of Tb just below the freezing level. In the case of convective precipitation, the focus was to investigate the effective additional rain layer thickness corresponding to the super-cooled water layer above the freezing level. From the results, it was required to assume the bright-band (around 1/2 km below the FL) as having 2 times the absorption as the rain below to explain the Tb variation due to the phase change of hydrometeors. On the other hand, in the case of convective rainfall, it was suggested that approximately from 1/4km to 3km of super-cooled layer thickness should be considered to describe the additional hydrometeor layer due to the strong updrafts in the convective regions.
Jin, Kyoung-Wook
Final measurement of $B^0_s$ mixing phase in the full CDF Run II data set
We report the final CDF measurement of the $B^0_s$ mixing phase, mean lifetime, and decay-width difference through the fit of the time evolution of flavor-tagged $B^0_s \\rightarrow J/\\psi \\phi$ decays. The measurement is based on the full data set of 1.96 TeV $p\\bar{p}$ collisions collected between February 2002 and September 2011 by the CDF experiment. The results are consistent with the standard model and other experimental determinations and are amongst the most precise to date.
Sabato Leo
Discrimination of Mixed- versus Ice-Phase Clouds Using Dual-Polarization Radar with Application to Detection of Aircraft Icing Regions
Dual-polarization radar measurements and in situ measurements of supercooled liquid water and ice particles within orographic cloud systems are used to develop probabilistic criteria for identifying mixed-phase versus ice-phase regions of sub-0�C ...
David M. Plummer; Sabine G�ke; Robert M. Rauber; Larry Di Girolamo
A Coordinated Effort to Improve Parameterization of High-Latitude Cloud and Radiation Processes
The goal of this project is the development and evaluation of improved parameterization of arctic cloud and radiation processes and implementation of the parameterizations into a climate model. Our research focuses specifically on the following issues: (1) continued development and evaluation of cloud microphysical parameterizations, focusing on issues of particular relevance for mixed phase clouds; and (2) evaluation of the mesoscale simulation of arctic cloud system life cycles.
J. O. Pinto, A.H. Lynch
Cirrus Cloud Microphysical Property Retrieval Using Lidar and Radar Measurements. Part II: Midlatitude Cirrus Microphysical and Radiative Properties
The lidar�radar algorithm described in Part I of this set of papers is applied to 1000 h of Raman lidar and millimeter wave cloud radar (MMCR) data collected at the Atmospheric Radiation Measurement program Southern Great Plains Clouds and ...
Nonaqueous seeded growth of flower-like mixed-phase titania nanostructures for photocatalytic applications
A nonaqueous seeded-grown synthesis of three-dimensional TiO{sub 2} nanostructures in the benzyl alcohol reaction system was reported. The synthesis was simple, high-yield, and requires no structural directing or capping agents. It could be largely accelerated by applying microwave heating. The TiO{sub 2} nanostructures had a unique flower-like morphology and high surface area. Furthermore, the structural analyses suggested that the nanostructures had a non-uniform distribution of crystalline phases, with the inner part rich in anatase and the outer part rich in rutile. After heat treatments, the mixed-phase TiO{sub 2} nanostructures exhibited high photocatalytic activities for the photodegradation of methylene blue as compared to Degussa P25. The high photoactivities may be associated with the high surface area and the synergistic effect resulting from the anisotropic mixed-phase nanostructures. The results demonstrate the uniqueness of the nonaqueous seeded growth and the potential of the TiO{sub 2} nanostructures for practical applications. - Graphical abstract: Flower-like TiO{sub 2} nanostructures synthesized by a nonaqueous seeded growth without using any structural directing or capping agents.
Hsu, Y.-C.; Lin, H.-C.; Chen, C.-H.; Liao, Y.-T. [Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Yang, C.-M., E-mail: email@example.com [Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan (China)
Global simulations of ice nucleation and ice supersaturation with an improved cloud scheme in the Community
and supersaturation in CAM. The new model is able to reproduce field observations of ice mass and mixed phase cloudGlobal simulations of ice nucleation and ice supersaturation with an improved cloud scheme; accepted 3 June 2010; published 28 September 2010. [1] A processbased treatment of ice supersaturation
Gettelman, Andrew
targeting the liquid, and radar, the ice. Depolarization measurements can assist in resolving phase to identify liquid, ice, and mixed-phase clouds. __________ NOTICE: This manuscript has been authored IMPLICATIONS FOR CLOUD PHASE IDENTIFICATION E. Luke, P. Kollias, and M. Shupe Presented at the American
Improved Airborne Hot-Wire Measurements of Ice Water Content in Clouds
Airborne measurements of ice water content (IWC) in both ice and mixed phase clouds remain one of the long standing problems in experimental cloud physics. For nearly three decades, IWC has been measured with the help of the Nevzorov hot-wire ...
A. Korolev; J. W. Strapp; G. A. Isaac; E. Emery
ISCCP Cloud Algorithm Intercomparison
The International Satellite Cloud Climatology Project (ISCCP) will provide a uniform global climatology of satellite-measured radiances and derive an experimental climatology of cloud radiative properties from these radiances. A pilot study to ...
W. B. Rossow; F. Mosher; E. Kinsella; A. Arking; M. Desbois; E. Harrison; P. Minnis; E. Ruprecht; G. Seze; C. Simmer; E. Smith
Demonstrating the Potential for First-Class Research in Underdeveloped Countries: Research on Stratospheric Aerosols and Cirrus Clouds Optical Properties, and Radiative Effects in Cuba (1988�2010)
Optical properties of stratospheric aerosols and cirrus clouds and their radiative effects are currently important subjects of research worldwide. Those investigations are typical of developed countries, conducted by several highly specialized groups ...
Juan Carlos Antu�a Marrero; Ren� Estevan Arredondo; Boris Barja Gonz�lez
Obtaining Best Estimates for the Microphysical and Radiative Properties of Tropical Ice Clouds from TWP-ICE In Situ Microphysical Observations
Best estimates of the bulk microphysical and radiative properties (ice water content, visible extinction, effective radius, and total concentration) are derived for three case studies of tropical ice clouds sampled during the Tropical Warm Pool ...
A. Protat; G. M. McFarquhar; J. Um; J. Delano�
A Global Climatology of Single-Layer and Overlapped Clouds and their Optical Properties Developed Using a New Algorithm Applied to Terra/MODIS Data
Global Climatology of Single-Layer and Overlapped Global Climatology of Single-Layer and Overlapped Clouds and their Optical Properties Developed Using a New Algorithm Applied to Terra/MODIS Data F.-L. Chang and Z. Li Earth System Science Interdisciplinary Center University of Maryland College Park, Maryland Z. Li Department of Meteorology University of Maryland College Park, Maryland Introduction To date, weather satellites are the only tool to measure cloud and climate variables on a global scale, an objective addressed by the International Satellite Cloud Climatology Project (ISCCP) (Rossow and Schiffer 1991; Rossow and Schiffer 1999). However, there is a dearth of information concerning the global climatology of cloud vertical structure and cirrus cloud properties. This is because the often-used
ARM - PI Product - Cloud-Scale Vertical Velocity and Turbulent Dissipation
ProductsCloud-Scale Vertical Velocity and Turbulent ProductsCloud-Scale Vertical Velocity and Turbulent Dissipation Rate Retrievals Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send PI Product : Cloud-Scale Vertical Velocity and Turbulent Dissipation Rate Retrievals Site(s) NSA General Description Time-height fields of retrieved in-cloud vertical wind velocity and turbulent dissipation rate, both retrieved primarily from vertically-pointing, Ka-band cloud radar measurements. Files are available for manually-selected, stratiform, mixed-phase cloud cases observed at the North Slope of Alaska (NSA) site during periods covering the Mixed-Phase Arctic Cloud Experiment (MPACE, late September through early November 2004) and the Indirect and Semi-Direct Aerosol Campaign (ISDAC, April-early May
A New Two-Moment Bulk Stratiform Cloud Microphysics Scheme in the Community Atmosphere Model, Version 3 (CAM3). Part II: Single-Column and Global Results
the importance of these interactions and the dif- ficulty in parameterizing clouds due to the wide range prognostic variables for cloud liquid and ice mass, specification of the effective cloud particle size for treating radiative interactions, and limited treatment of mixed-phase processes. There are several
Analysis of Aircraft, Radiosonde, and Radar Observations in Cirrus Clouds Observed during FIRE II: The Interactions between Environmental Structure, Turbulence, and Cloud Microphysical Properties
Ways to determine the turbulence intensity and the horizontal variability in cirrus clouds have been investigated using First International Satellite Cloud Climatology Project (ISCCP) Regional Experiment II aircraft, radiosonde, and radar data. ...
Samantha A. Smith; Anthony D. DelGenio
Testing Cloud Microphysics Parameterizations in NCAR CAM5 with ISDAC and M-PACE Observations
Arctic clouds simulated by the NCAR Community Atmospheric Model version 5 (CAM5) are evaluated with observations from the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Indirect and Semi-Direct Aerosol Campaign (ISDAC) and Mixed-Phase Arctic Cloud Experiment (M-PACE), which were conducted at its North Slope of Alaska site in April 2008 and October 2004, respectively. Model forecasts for the Arctic Spring and Fall seasons performed under the Cloud- Associated Parameterizations Testbed (CAPT) framework generally reproduce the spatial distributions of cloud fraction for single-layer boundary layer mixed-phase stratocumulus, and multilayer or deep frontal clouds. However, for low-level clouds, the model significantly underestimates the observed cloud liquid water content in both seasons and cloud fraction in the Spring season. As a result, CAM5 significantly underestimates the surface downward longwave (LW) radiative fluxes by 20-40 W m-2. The model with a new ice nucleation parameterization moderately improves the model simulations by increasing cloud liquid water content in mixed-phase clouds through the reduction of the conversion rate from cloud liquid to ice by the Wegener-Bergeron- Findeisen (WBF) process. The CAM5 single column model testing shows that change in the homogeneous freezing temperature of rain to form snow from -5 C to -40 C has a substantial impact on the modeled liquid water content through the slowing-down of liquid and rain-related processes. In contrast, collections of cloud ice by snow and cloud liquid by rain are of minor importance for single-layer boundary layer mixed-phase clouds in the Arctic.
Liu, Xiaohong; Xie, Shaocheng; Boyle, James; Klein, Stephen A.; Shi, Xiangjun; Wang, Zhien; Lin, Wuyin; Ghan, Steven J.; Earle, Michael; Liu, Peter; Zelenyuk, Alla
Arctic clouds simulated by the National Center for Atmospheric Research (NCAR) Community Atmospheric Model version 5 (CAM5) are evaluated with observations from the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Indirect and Semi-Direct Aerosol Campaign (ISDAC) and Mixed-Phase Arctic Cloud Experiment (M-PACE), which were conducted at its North Slope of Alaska site in April 2008 and October 2004, respectively. Model forecasts for the Arctic spring and fall seasons performed under the Cloud-Associated Parameterizations Testbed framework generally reproduce the spatial distributions of cloud fraction for single-layer boundary-layer mixed-phase stratocumulus and multilayer or deep frontal clouds. However, for low-level stratocumulus, the model significantly underestimates the observed cloud liquid water content in both seasons. As a result, CAM5 significantly underestimates the surface downward longwave radiative fluxes by 20-40 W m{sup -2}. Introducing a new ice nucleation parameterization slightly improves the model performance for low-level mixed-phase clouds by increasing cloud liquid water content through the reduction of the conversion rate from cloud liquid to ice by the Wegener-Bergeron-Findeisen process. The CAM5 single-column model testing shows that changing the instantaneous freezing temperature of rain to form snow from -5 C to -40 C causes a large increase in modeled cloud liquid water content through the slowing down of cloud liquid and rain-related processes (e.g., autoconversion of cloud liquid to rain). The underestimation of aerosol concentrations in CAM5 in the Arctic also plays an important role in the low bias of cloud liquid water in the single-layer mixed-phase clouds. In addition, numerical issues related to the coupling of model physics and time stepping in CAM5 are responsible for the model biases and will be explored in future studies.
Liu X.; Lin W.; Xie, S.; Boyle, J.; Klein, S. A.; Shi, X.; Wang, Z.; Ghan, S. J.; Earle, M.; Liu, P. S. K.; Zelenyuk, A.
Range�Height Scans of Lidar Depolarization for Characterizing Properties and Phase of Clouds and Precipitation
Backscatter and depolarization lidar measurements from clouds and precipitation are reported as functions of the elevation angle of the pointing lidar direction. The data were recorded by scanning the lidar beam (Nd:YAG) at a constant angular ...
Luc R. Bissonnette; Gilles Roy; Fr�d�ric Fabry
Cirrus Microphysical Properties and Air Motion Statistics Using Cloud Radar Doppler Moments. Part II: Climatology
The algorithm described in Part I has been applied to the millimeter cloud radar observations from January 1999 to December 2005 at the Atmospheric Radiation Measurement Program (ARM) Southern Great Plains (SGP) and Tropical Western Pacific (...
Min Deng; Gerald G. Mace
Laboratory Studies of Scattering Properties of Polluted Cloud Droplets: Implications for FSSP Measurements
Laboratory experiments were conducted in the Mainz vertical wind tunnel to study the effects of pollutants dissolved or suspended in cloud droplets on the droplet size measurements of a Forward Scattering Spectrometer Probe (FSSP). The FSSP is a ...
Karoline Diehl; G�nter Huber; Subir K. Mitra; Manfred Wendisch
An Evaluation of a 94-GHz Radar for Remote Sensing of Cloud Properties
The performance of a 94-GHz radar is evaluated for a variety of cloud conditions. Descriptions of the radar hardware, signal processing, and calibration provide an overview of the radar's capabilities. An important component of the signal ...
E. E. Clothiaux; M. A. Miller; B. A. Albrecht; T. P. Ackerman; J. Verlinde; D. M. Babb; R. M. Peters; W. J. Syrett
Remote Sensing of Cloud Optical Properties from Ground-Based Measurements of Transmittance: A Feasibility Study
The authors present a retrieval technique for the inference of cloud optical depth from data obtained by a ground-based multichannel radiometer for use in climate-related studies. The basic steps of the analysis procedure are considered, ...
E. Leontieva; K. Stamnes
Validating Model Clouds and Their Optical Properties Using Geostationary Satellite Imagery
A real-time validation scheme for diagnosing radiatively active clouds has been in operation for a number of years at the Australian Bureau of Meteorology. It compares IR channel imagery from four geostationary satellites and equivalent forward ...
Zhian Sun; Lawrie Rikus
Remote Sensing of Surface and Cloud Properties in the Arctic from AVHRR Measurements
Algorithms to retrieve cloud optical depth and effective radius in the Arctic using Advanced Very High Resolution Radiometer (AVHRR) data are developed, using a comprehensive radiative transfer model in which the atmosphere is coupled to the ...
W. Han; K. Stamnes; Dan Lubin
Investigation of Regional and Seasonal Variations in Marine Boundary Layer Cloud Properties from MODIS Observations
To aid in understanding the role that marine boundary layer (MBL) clouds play in climate and assist in improving their representations in general circulation models (GCMs), their long-term microphysical and macroscale characteristics are ...
Michael P. Jensen; Andrew M. Vogelmann; William D. Collins; Guang J. Zhang; Edward P. Luke
A Missing Solution to the Transport Equation and Its Effect on Estimation of Cloud Absorptive Properties
Most of the existing cloud radiation models treat liquid water drops of a variety of sizes as an ensemble of particles. The ensemble approach assumes that all drop sizes are well represented in an elementary volume, and its scattering and ...
Y. Knyazikhin; A. Marshak; W. J. Wiscombe; J. V. Martonchik; R. B. Myneni
Radiative Properties of Boundary Layer Clouds: Droplet Effective Radius versus Number Concentration
The plane-parallel model for the parameterization of clouds in global climate models is examined in order to estimate the effects of the vertical profile of the microphysical parameters on radiative transfer calculations for extended boundary ...
Jean-Louis Brenguier; Hanna Pawlowska; Lothar Sch�ller; Rene Preusker; J�rgen Fischer; Yves Fouquart
Computation of Domain-Averaged Irradiance Using Satellite-Derived Cloud Properties
The respective errors caused by the gamma-weighted two-stream approximation and the effective thickness approximation for computing the domain-averaged broadband shortwave irradiance are evaluated using cloud optical thicknesses derived from 1 h ...
Seiji Kato; Fred G. Rose; Thomas P. Charlock
Retrieval of Cloud Microphysical Properties from Thermal Infrared Observations by a Fast Iterative Radiance Fitting Method
An algorithm is presented for inferring the IR optical depth, effective radius, and liquid water path of clouds from multispectral observations of emitted thermal radiation, which takes advantage of the larger number of spectral channels of ...
C. Rathke; J. Fischer
Estimation of Liquid Cloud Properties that Conserve Total-Scene Reflectance Using Satellite Measurements
A new method of deriving statistical moments related to the distribution of liquid water path over partially cloudy scenes is tested using a satellite cloud climatology. The method improves the ability to reconstruct total-scene visible ...
Michael J. Foster; Ralf Bennartz; Andrew Heidinger
Evolution of Severe and Non-severe Convection Inferred from GOES-derived Cloud Properties
Geostationary satellites (e.g. Geostationary Operational Environmental Satellite [GOES]) provide high temporal resolution of cloud development and motion, which is essential to the study of many mesoscale phenomena, including thunderstorms. ...
John L. Cintineo; Michael J. Pavolonis; Justin M. Sieglaff; Andrew K. Heidinger
We investigate the physical properties of dense cores formed in turbulent, magnetized, parsec-scale clumps of molecular clouds, using three-dimensional numerical simulations that include protostellar outflow feedback. The dense cores are identified in the simulated density data cube through a clumpfind algorithm. We find that the core velocity dispersion does not show any clear dependence on the core size, in contrast to Larson's linewidth-size relation, but consistent with recent observations. In the absence of a magnetic field, the majority of the cores have supersonic velocity dispersions. A moderately strong magnetic field reduces the dispersion to a subsonic or at most transonic value typically. Most of the cores are out of virial equilibrium, with the external pressure dominating the self-gravity. The implication is that the core evolution is largely controlled by the outflow-driven turbulence. Even an initially weak magnetic field can retard star formation significantly, because the field is amplified by the outflow-driven turbulence to an equipartition strength, with the distorted field component dominating the uniform one. In contrast, for a moderately strong field, the uniform component remains dominant. Such a difference in the magnetic structure is evident in our simulated polarization maps of dust thermal emission; it provides a handle on the field strength. Recent polarization measurements show that the field lines in cluster-forming clumps are spatially well ordered. It is indicative of a moderately strong, dynamically important field which, in combination with outflow feedback, can keep the rate of star formation in embedded clusters at the observationally inferred, relatively slow rate of several percent per free-fall time.
Nakamura, Fumitaka [National Astronomical Observatory, Mitaka, Tokyo 181-8588 (Japan); Li Zhiyun, E-mail: email@example.com, E-mail: firstname.lastname@example.com [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904 (United States)
Global Distribution and Climate Forcing of Marine Organic Aerosol - Part 2: Effects on Cloud Properties and Radiative Forcing
A series of simulations with the Community Atmosphere Model version 5 (CAM5) with a 7-mode Modal Aerosol Model were conducted to assess the changes in cloud microphysical properties and radiative forcing resulting from marine organic aerosols. Model simulations show that the anthropogenic aerosol indirect forcing (AIF) predicted by CAM5 is decreased in absolute magnitude by up to 0.09 Wm{sup -2} (7 %) when marine organic aerosols are included. Changes in the AIF from marine organic aerosols are associated with small global increases in low-level incloud droplet number concentration and liquid water path of 1.3 cm{sup -3} (1.5 %) and 0.22 gm{sup -2} (0.5 %), respectively. Areas especially sensitive to changes in cloud properties due to marine organic aerosol include the Southern Ocean, North Pacific Ocean, and North Atlantic Ocean, all of which are characterized by high marine organic emission rates. As climate models are particularly sensitive to the background aerosol concentration, this small but non-negligible change in the AIF due to marine organic aerosols provides a notable link for ocean-ecosystem marine low-level cloud interactions and may be a candidate for consideration in future earth system models.
Gantt, Brett; Xu, Jun; Meskhidze, N.; Zhang, Yang; Nenes, Athanasios; Ghan, Steven J.; Liu, Xiaohong; Easter, Richard C.; Zaveri, Rahul A.
Theory for Dual-Wavelength C02 Lidar Method to Distinguish Ice, Mixed-Phase, and Water Clouds
An analytical study shows that the ratio of backscatter from ice particles at two CO2 lidar wavelengths is substantially different from the ratio from water drops. This forms the basis for a new method to discriminate between ice, water, and ...
Wynn L. Eberhard
Statistical Analysis of Forecasting Models across the North Slope of Alaska during the Mixed-Phase Arctic Clouds Experiment
The National Centers for Environmental Prediction�s (NCEP) Eta Model, the models of the European Centre for Medium-Range Weather Forecasts (ECMWF) and the National Aeronautics and Space Administration�s (NASA) Global Modeling and Assimilation ...
Victor T. Yannuzzi; Eugene E. Clothiaux; Jerry Y. Harrington; Johannes Verlinde
FINAL REPORT FOR THE DOE/ARM PROJECT TITLED Representation of the Microphysical and Radiative Properties of Ice Clouds in SCMs and GCMs
The broad goal of this research is to improve climate prediction through better representation of cirrus cloud microphysical and radiative properties in global climate models (GCMs). Clouds still represent the greatest source of uncertainty in climate prediction, and the representation of ice clouds is considerably more challenging than liquid water clouds. While about 40% of cloud condensate may be in the form of ice by some estimates, there have been no credible means of representing the ice particle size distribution and mass removal rates from ice clouds in GCMs. Both factors introduce large uncertainties regarding the global net flux, the latter factor alone producing a change of 10 W/m2 in the global net flux due to plausible changes in effective ice particle fallspeed. In addition, the radiative properties of ice crystals themselves are in question. This research provides GCMs with a credible means of representing the full (bimodal) ice particle size distribution (PSD) in ice clouds, including estimates of the small crystal (D < 65 microns) mode of the PSD. It also provides realistic estimates of mass sedimentation rates from ice clouds, which have a strong impact on their ice contents and radiative properties. This can be done through proper analysis of ice cloud microphysical data from ARM and other field campaigns. In addition, this research tests the ice cloud radiation treatment developed under two previous ARM projects by comparing it against laboratory measurements of ice cloud extinction efficiency and by comparing it with explicit theoretical calculations of ice crystal optical properties. The outcome of this project includes two PSD schemes for ice clouds; one appropriate for mid-latitude cirrus clouds and another for tropical anvil cirrus. Cloud temperature and ice water content (IWC) are the inputs for these PSD schemes, which are based on numerous PSD observations. The temperature dependence of the small crystal mode of the PSD for tropical anvils is opposite to that of mid-latitude cirrus, and this results in very different radiative properties for these two types of cirrus at temperatures less than about 50 C for a given ice water path. In addition, the representative PSD fall velocity is strongly influenced by the small crystal mode, and for temperatures less than 52 C, this fall velocity for mid-latitude cirrus is 2-8 times greater than for tropical anvil cirrus. Finally, the treatment of ice cloud optical properties was found to agree with laboratory measurements and exact theory within 15% for any given wavelength, PSD and ice particle shape. This treatment is analytical, formulated in terms of the PSD and ice particle shape properties. It thus provides the means for explicitly coupling the ice cloud microphysical and radiative properties, and can treat any combination of ice particle shape. It is very inexpensive regarding computer time. When these three deliverables were incorporated into the GCM at the National Center for Atmospheric Research (NCAR) under another project, it was found that the sunlight reflected and the amount of upwelling heat absorbed by cirrus clouds depended strongly on the PSD scheme used (i.e. mid-latitude or tropical anvil). This was largely due to the fall velocities associated with the two PSD schemes, although the PSD shape was also important.
Mitchell, David L.
Cloud Microphysical and Radiative Properties Derived from MODIS, VIRS, AVHRR, and GMS Data Over the Tropical Western Pacific
Microphysical and Radiative Properties Derived Microphysical and Radiative Properties Derived from MODIS, VIRS, AVHRR, and GMS Data Over the Tropical Western Pacific G. D. Nowicki, M. L. Nordeen, P. W. Heck, D. R. Doelling, and M. M. Khaiyer Analytical Services and Materials, Inc. Hampton, Virginia P. Minnis National Aeronautics and Space Administration Atmospheric Sciences Division Langley Research Center Hampton, Virginia S. Sun-Mack Science Applications International Corporation Hampton, Virginia Introduction Utilization of the geostationary meteorological satellite (GMS) imagery has allowed for the derivation of cloud and radiative properties over the Tropical Western Pacific (TWP) on relatively high spatial and temporal scales. The layered bispectral threshold method (LBTM) has been applied to GMS data
Analysis of In situ Observations of Cloud Microphysics from M-PACE Final Report, DOE Grant Agreement No. DE-FG02-06ER64168
This report summarizes the findings and accomplishments of work performed under DOE Grant Agreement No. DE-FG02-06ER64168. The focus of the work was the analysis of in situ observations collected by the University of North Dakota Citation research aircraft during the Mixed-Phase Arctic Cloud Experiment (M-PACE). This project was conducted in 2004 along the North Slope of Alaska. The objectives of the research were: to characterize certain microphysical properties of clouds sampled during M-PACE, including spatial variability, precipitation formation, ice multiplication; to examine instrument performance and certain data processing algorithms; and to collaborate with other M-PACE investigators on case study analyses. A summary of the findings of the first two objectives is given here in parts 1 and 2; full results are contained in reports listed in part 3 of this report. The collaborative efforts are described in the publications listed in part 3.
Michael R. Poellot
The Properties and Formation of Cirrus Clouds over the Tibetan Plateau Based on Summertime Lidar Measurements
As part of the Tibet Ozone, Aerosol and Radiation (TOAR) project, a micropulse lidar was operated in Naqu (31.5�N, 92.1�E; 4508 m MSL) on the Tibetan Plateau to observe cirrus clouds continuously from 19 July to 26 August 2011. During the ...
Q. S. He; C. C. Li; J. Z. Ma; H. Q. Wang; G. M. Shi; Z. R. Liang; Q. Luan; F. H. Geng; X. W. Zhou
BNL | Aerosol, Cloud, Precipitation Interactions
Cloud-Aerosol-Precipitation Interactions Cloud-Aerosol-Precipitation Interactions Atmospheric aerosols exert important "indirect effects" on clouds and climate by serving as cloud condensation nuclei (CCN) and ice nuclei that affect cloud radiative and microphysical properties. For example, an increase in CCN increases the number concentration of droplets enhances cloud albedo, and suppresses precipitation that alters cloud coverage and lifetime. However, in the case of moist and strong convective clouds, increasing aerosols may increase precipitation and enhance storm development. Although aerosol-induced indirect effects on climate are believed to have a significant impact on global climate change, estimating their impact continues to be one of the most uncertain climate forcings.
Studying Clouds and Aerosols with Lidar Depolarization Ratio and Backscatter Relationships
This dissertation consists of three parts, each devoted to a particular issue of significant importance for CALIPSO lidar observation of depolarization ratio (delta) and backscatter (gamma?) to improve current understanding of the microphysical properties of clouds and aerosols. The relationships between depolarization ratio and backscatter allow us to retrieve particle thermodynamic phase and shape and/or orientation of aerosols and clouds. The first part is devoted to the investigation of the relationships between lidar backscatter and the corresponding depolarization ratio for different cloud classifications and aerosol types. For each cloud and aerosol types, layer-averaged backscatter and backscattering depolarization ratio from the CALIPSO measurements are discussed. The present results demonstrate the unique capabilities of the CALIPSO lidar instrument for determining cloud phase and aerosols subtypes. In the second part, we evaluate the MODIS IR cloud phase with the CALIPSO cloud products. The three possible misclassifications of MODIS IR cloud phasealgorithm, which are studied by Nasiri and Kahn (2008) with radiative transfer modeling, are tested by comparing between MODIS IR phase and CALIOP observations. The current results support their hypotheses, which is that the MODIS phase algorithm may tend to classify thin cirrus clouds as water clouds or mixed phase clouds or unknown, and classify midlevel and/or mid-temperature clouds as mixed or unknown phase. In the third part, we present a comparison of mineral dust aerosol retrievals from two instruments, MODIS and CALIPSO lidar. And, we implement and evaluate a new mineral dust detection algorithm based on the analysis of thin dust radiative signature. In comparison, three commonly used visible and IR mineral dust detection algorithms, including BTD procedure, D parameter method, and multi-channel image algorithm, are evaluated with CALIPSO aerosol classification. The comparison reveals that those dust detection algorithms are not effective for optically thin dust layers, but for thick dust storm. The new algorithm using discriminant analysis with CALIPSO observation is much better in detecting thin dust layer of optical thickness between 0.1 and 2.
Cho, Hyoun-Myoung
Radiative Effects of Cloud Inhomogeneity and
cloud-overlap assumptions and optical property approximations (Del Genio et al. 1996; Fowler and Randall 1996; Liang and Wang 1997). While GCMs require convection and cloud...
A Ten-Winter Record of Cloud-Droplet Physical and Chemical Properties at a Mountaintop Site in Colorado
Cloud-droplet spectra and coincident cloud water pH measurements have been made for a portion of ten consecutive winters (1983/84?1992/93) from clouds that enveloped Storm Peak Laboratory in northwestern Colorado; cloud water ion measurements ...
Edward E. Hindman; Mechel A. Campbell; Randolph D. Borys
Cloud Properties Simulated by a Single-Column Model. Part II: Evaluation of Cumulus Detrainment and Ice-Phase Microphysics Using a Cloud-Resolving Model
This paper is the second in a series in which kilometer-scale-resolving observations from the Atmospheric Radiation Measurement Program and output from the University of California, Los Angeles/Colorado State University cloud-resolving model (CRM)...
Yali Luo; Steven K. Krueger; Kuan-Man Xu
Objective Assessment of the Information Content of Visible and Infrared Radiance Measurements for Cloud Microphysical Property Retrievals over the Global Oceans. Part I: Liquid Clouds
The importance of accurately representing the role of clouds in climate change studies has become increasingly apparent in recent years, leading to a substantial increase in the number of satellite sensors and associated algorithms that are ...
Tristan S. L�Ecuyer; Philip Gabriel; Kyle Leesman; Steven J. Cooper; Graeme L. Stephens
Clouds at Arctic Atmospheric Observatories. Part II: Thermodynamic Phase Characteristics
Cloud phase defines many cloud properties and determines the ways in which clouds interact with other aspects of the climate system. The occurrence fraction and characteristics of clouds distinguished by their phase are examined at three Arctic ...
Matthew D. Shupe
Investigation of Thin Cirrus Cloud Optical and Microphysical Properties on the Basis of Satellite Observations and Fast Radiative Transfer Models
This dissertation focuses on the global investigation of optically thin cirrus cloud optical thickness (tau) and microphysical properties, such as, effective particle size (D_(eff)) and ice crystal habits (shapes), based on the global satellite observations and fast radiative transfer models (RTMs). In the first part, we develop two computationally efficient RTMs simulating satellite observations under cloudy-sky conditions in the visible/shortwave infrared (VIS/SWIR) and thermal inferred (IR) spectral regions, respectively. To mitigate the computational burden associated with absorption, thermal emission and multiple scattering, we generate pre-computed lookup tables (LUTs) using two rigorous models, i.e., the line-by-line radiative transfer model (LBLRTM) and the discrete ordinates radiative transfer model (DISORT). The second part introduces two methods (i.e., VIS/SWIR- and IR-based methods) to retrieve tau and D_(eff) from satellite observations in corresponding spectral regions of the two RTMs. We discuss the advantages and weakness of the two methods by estimating the impacts from different error sources on the retrievals through sensitivity studies. Finally, we develop a new method to infer the scattering phase functions of optically thin cirrus clouds in a water vapor absorption channel (1.38-�m). We estimate the ice crystal habits and surface structures by comparing the inferred scattering phase functions and numerically simulated phase functions calculated using idealized habits.
Wang, Chenxi
Microsoft Word - wang_z.doc
Algorithms The Mixed-Phase Cloud Microphysical Property Retrieval Supercooled water with ice virga is a typical type of mixed-phase cloud in arctic, which can be generally...
A Midlatitude Cirrus Cloud Climatology from the Facility for Atmospheric Remote Sensing. Part I: Macrophysical and Synoptic Properties
A uniquely extensive high cloud dataset has been collected from the University of Utah Facility for Atmospheric Remote Sensing in support of the First (ISCCP) International Satellite Cloud Climatology Project Regional Experiment extended time ...
Kenneth Sassen; James R. Campbell
Sensitivity Analysis of Cirrus Cloud Properties from High-Resolution Infrared Spectra. Part I: Methodology and Synthetic Cirrus
A set of simulated high-resolution infrared (IR) emission spectra of synthetic cirrus clouds is used to perform a sensitivity analysis of top-of-atmosphere (TOA) radiance to cloud parameters. Principal component analysis (PCA) is applied to ...
Brian H. Kahn; Annmarie Eldering; Michael Ghil; Simona Bordoni; Shepard A. Clough
The 27�28 October 1986 FIRE IFO Cirrus Case Study: Spectral Properties of Cirrus Clouds in the 8�12 ?m Window
Lidar and high spectral resolution infrared radiance observations taken on board the ER-2 on 28 October 1986 are used to study the radiative properties of cirrus cloud in the 8�12 ?m window region. Measurements from the High-spectral resolution ...
Steven A. Ackerman; W. L. Smith; H. E. Revercomb; J. D. Spinhirne
Development and Comparison of Ground and Satellite-based Retrievals of Cirrus Cloud Physical Properties
This report is the final update on ARM research conducted at DRI through May of 2006. A relatively minor amount of work was done after May, and last month (November), two journal papers partially funded by this project were published. The other investigator on this project, Dr. Bob d'Entremont, will be submitting his report in February 2007 when his no-cost extension expires. The main developments for this period, which concludes most of the DRI research on this project, are as follows: (1) Further development of a retrieval method for cirrus cloud ice particle effective diameter (De) and ice water path (IWP) using terrestrial radiances measured from satellites; (2) Revision and publication of the journal article 'Testing and Comparing the Modified Anomalous Diffraction Approximation'; and (3) Revision and publication of our radar retrieval method for IWC and snowfall rate.
Mitchell, David L
IC cloud: Enabling compositional cloud
Cloud computing has attracted great interest from both academic and industrial communities. Different paradigms, architectures and applications based on the concept of cloud have emerged. Although many of them have been quite successful, efforts are ... Keywords: Cloud computing, cloud elasticity, cloud service, compositional cloud, infrastructure as a service (IaaS)
Yi-Ke Guo; Li Guo
Remote Sounding of High Clouds. V: Infrared Properties and Structures of Tropical Thunderstorm Anvils
The infrared properties and structures of some anvils emanating from local thunderstorms were studied by lidar and infrared radiometry at Darwin, tropical Northern Australia. The anvils were typically from 1 to 2 km deep, at altitudes from 7 to ...
C. M. R. Platt; A. C. Dilley; J. C. Scott; I. J. Barton; G. L. Stephens
Retrieval of Cirrus Cloud Radiative and Backscattering Properties Using Combined Lidar and Infrared Radiometer (LIRAD) Measurements
A method for retrieval of cirrus macrophysical and radiative properties using combined ruby lidar and infrared radiometer measurements is explained in detail. The retrieval algorithm includes estimation of a variable backscatter-to-extinction ...
Jennifer M. Comstock; Kenneth Sassen
Climatology of High Cloud Dynamics Using Profiling ARM Doppler Radar Observations
Ice cloud properties are influenced by cloud-scale vertical air motion. Dynamical properties of ice clouds can be determined via Doppler measurements from ground-based, profiling cloud radars. Here, the decomposition of the Doppler velocities into ...
Heike Kalesse; Pavlos Kollias
Use of ARM/NSA Data to Validate and Improve the Remote Sensing Retrieval of Cloud and Surface Properties in the Arctic from AVHRR Data
ARM/NSA Data to Validate and Improve the ARM/NSA Data to Validate and Improve the Remote Sensing Retrieval of Cloud and Surface Properties in the Arctic from AVHRR Data X. Xiong QSS Group, Inc. National Oceanic and Atmospheric Administration National Environmental Satellite, Data, and Information Service Office of Research and Applications Camp Springs, Maryland R. Storvold and C. Marty Geophysical Institute University of Alaska Fairbanks, Alaska K. H. Stamnes Stevens Institute of Technology Hoboken, New Jersey B. D. Zak Sandia National Laboratories Albuquerque, New Mexico Introduction Clouds in the Arctic have an important impact on the radiative energy balance. However, the effects of clouds still constitute one of the largest uncertainties in the study of climate change. Because the surface
Observations of Cloud-Top Entrainment in Marine Stratocumulus Clouds
Measurements of the thermodynamic and dynamic properties of entrainment events in marine stratocumulus are used to explain why cloud-top entrainment instability may not lead to the breakup of the clouds and to define the role of cloud-top ...
Qing Wang; Bruce A. Albrecht
Subarctic atmospheric aerosol composition: 3. Measured and modeled properties of cloud condensation nuclei
Predicting the ability of aerosol particles to act as cloud condensation nuclei (CCN) is still a challenge and not properly incorporated in current climate models. By using field data from measurements at the sub-arctic Stordalen site, approximately 200 km north of the Arctic Circle, a hygroscopicity closure study was performed. Measured CCN number concentrations were compared with predictions that involved size distribution data and hygroscopicity data measured by a HTDMA as a proxy for the chemical composition of the aerosol. The sensitivity of the predictions to simplifying assumptions re-garding mixing state of the particles and the temporal variability of the chemical composition were explored. It was found that involving the full growth factor probability density function (GF-PDF) or the averaged growth factor (GF) or a constant averaged ?-value resulted in reasonable agreement be-tween predicted and measured CCN number concentrations. Probability distribution histograms of the performances of the different closure approaches revealed that involving the full GF-PDF resulted in the narrowest and most symmetric distribution of the predicted-to-measured CCN number concentra-tion ratio around unity. While also involving the averaged GF showed a good agreement, the constant averaged ?-value-approach resulted in most of the cases in an overestimation of CCN number con-centrations by ~15 %. Approaches where a constant estimated hygroscopicity was involved predicted CCN number concentrations in some cases well but largely overestimated (assuming internally mixed ammonium sulphate particles) or underestimated (assuming internally mixed organic aerosol particles with ? = 0.1) CCN number concentrations. It is therefore recommended that at least an averaged measured proxy for the aerosol�s chemical composition be incorporated in future CCN predictions and climate models.
Kammermann, Lukas; Gysel, Martin; Weingartner, E.; Herich, Hanna; Holst, Thomas; Cziczo, Daniel J.; Svenningsson, Birgitta; Arneth, Almut; Baltensperger, Urs
One-Particle Spectral Function and Local Density of States in a Phenomenological Mixed-Phase Model for High-Temperature Superconductors
The dynamical properties of a recently introduced phenomenological model for high-temperature superconductors are investigated. In the clean limit, it was observed that none of the homogeneous or striped states that are induced by the model at low temperatures can reproduce the recent angle-resolved photoemission results for La{sub 2-x}Sr{sub x}CuO{sub 4} [Yoshida et al., Phys. Rev. Lett. 91, 027001 (2003)], which show a signal with two branches in the underdoped regime. On the other hand, upon including quenched disorder in the model and breaking the homogeneous state into 'patches' that are locally either superconducting or antiferromagnetic, the two-branch spectra can be reproduced. In this picture, the nodal regions are caused by d-wave superconducting clusters. Studying the density of states (DOS), a pseudogap is observed, caused by the mixture of the gapped antiferromagnetic state and a d-wave superconductor. The local DOS can be interpreted using a mixed-phase picture, similar to what is observed in tunneling experiments. It is concluded that a simple phenomenological model for cuprates can capture several of the one-particle features observed in the underdoped regime of these materials.
Mayr, Matthias [Max-Planck-Institut fur Feskorperforschung, Stuttgart, Germany; Alvarez, Gonzalo [ORNL; Moreo, Adriana [ORNL; Dagotto, Elbio R [ORNL
Tropical cloud properties as a function of regime Regimes? Monsoon versus Break * Different synoptic vertical velocity profiles - Changes convective inhibition, corresponding...
ARM - Measurement - Cloud extinction
extinction extinction ARM Data Discovery Browse Data Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Measurement : Cloud extinction The removal of radiant energy from an incident beam by the process of cloud absorption and/or scattering. Categories Cloud Properties Instruments The above measurement is considered scientifically relevant for the following instruments. Refer to the datastream (netcdf) file headers of each instrument for a list of all available measurements, including those recorded for diagnostic or quality assurance purposes. ARM Instruments NEPHELOMETER : Nephelometer Field Campaign Instruments CEP : Cloud Extinction Probe CLDAEROSMICRO : Cloud and Aerosol Microphysical Properties EC-CONVAIR580-BULK : Environment Canada Convair 580 Bulk Parameters
A Model Predicting the Evolution of Ice Particle Size Spectra and Radiative Properties of Cirrus Clouds. Part I: Microphysics
A Lagrangian time-dependent three-dimensional model was developed that predicts the evolution of ice particle size spectra in cirrus clouds in terms of the growth processes of vapor diffusion and aggregation, as well as the cloud updraft profile. ...
David L. Mitchell
Effects of turbulent mixing on the structure and macroscopic properties of stratocumulus clouds demonstrated by a Lagrangian trajectory model
The role of turbulent mixing in formation of the structure of stratocumulus clouds is investigated using a Lagrangian-Eulerian parcel cloud model containing ~2000-5000 adjacent parcels with the linear size of 25-40 m, moving with a turbulent-like ...
L. Magaritz-Ronen; M. Pinsky; A. Khain
The convective structures associated with cloud-to-ground lightning in TOGA COARE Mesoscale Convective Systems
The TOGA COARE experiment was carried out in the western Pacific warm pool region from November 1992 through February 1993. Data from TOGA COARE provide the opportunity for comprehensive studies of tropical oceanic convection. This study seeks to understand more about the structures of tropical mesoscale convective systems in relation to their lightning activity and cold cloud area. The properties of convective cores within the MCSs, as well as their infrared (IR) cloud top temperatures are related to cloud-to-ground lightning. IR and lightning time histories for each case are compared, and the cases ranked by mean flashes per 10000 km2. For selected cases, radar/lightning overlays and vertical profiles of maximum radar reflectivities (VPRRs) are shown in order to describe the convective structures of cells that produced lightning, and also cells that did not produce lightning. IR cloud-top temperature and lightning histories indicate the highly variable nature of the TOGA COARE MCSs. Some MCSs which have very cold cloud-top temperatures have little or no lightning. When a system did produce lightning, more flashes generally occurred during its growth phase. Overall, IR measurements seem to be a poor indicator of lightning due to the lack of a clear relationship between the size of cold cloud-top area and cloud-to-ground flashes. The overall flash rates of the TOGA COARE MCSs support previous work which showed that tropical oceanic convection has an order of magnitude less cloud-to-ground lightning than continental convection. In fact, the highest flash rate for the 13 cases was less than the weakest continental case in a Texas MCS study (Toracinta et al. 1995). Examination of individual VPRR and of all convective VPRR from the 13 cases indicate a pronounced difference between lightning producing and non-lightning producing cells. Lightning producing convective cells have higher radar reflectivity in the 5.0- 8.0 km layer, and a slower decrease with height, both observations indicating larger ice particles in the mixed phase region between 00 C and-200 C.
Restivo, Michael Edward
The Effects of Clouds on Aerosol and Chemical Species Production and Distribution. Part III: Aerosol Model Description and Sensitivity Analysis
A modeling study of the effects of clouds on the evolution and redistribution of aerosol particles in the troposphere is presented. A two-mode, two-moment aerosol evolution model is coupled with a two-dimensional, mixed-phase, two-moment ...
Yiping Zhang; Sonia Kreidenweis; Gregory R. Taylor
Two-moment Bulk Stratiform Cloud Microphysics in the Grid-point Atmospheric Model of IAP LASG (GAMIL)
A two-moment bulk stratiform microphysics scheme, including recently developed physically-based droplet activation/ice nucleation parameterizations has been implemented into the Grid-point Atmospheric Model of IAP LASG (GAMIL) as an effort to enhance the model capability for studying aerosol indirect effects. Unlike the previous one-moment cloud microphysics scheme, the new scheme produces reasonable representation of cloud particle size and number concentration. This scheme captures the observed spatial variations in cloud droplet number concentrations. Simulated ice crystal number concentrations in cirrus clouds qualitatively agree with in-situ observations. The longwave and shortwave cloud forcing are in better agreement with observations. Sensitivity tests show that the column cloud droplet number concentrations calculated from two different droplet activation parameterizations are similar. However, ice crystal number concentration in mixed-phased clouds is sensitive to different heterogeneous freezing formulations. The simulation with high ice crystal number concentration in mixed-phase clouds has less liquid water path and weaker cloud forcing. Furthermore, ice crystal number concentration in cirrus clouds is sensitive to different ice nucleation parameterizations. Sensitivity tests also suggest that impact of pre-existing ice crystals on homogeneous freezing in old clouds should be taken into account.
Shi, Xiangjun; Wang, Bin; Liu, Xiaohong; Wang, Minghuai
A Method for Forecasting Cloud Condensation Nuclei Using Predictions of Aerosol Physical and Chemical Properties from WRF/Chem
Model investigations of aerosol�cloud interactions across spatial scales are necessary to advance basic understanding of aerosol impacts on climate and the hydrological cycle. Yet these interactions are complex, involving numerous physical and ...
Daniel Ward; William Cotton
A Midlatitude Cirrus Cloud Climatology from the Facility for Atmospheric Remote Sensing. Part II: Microphysical Properties Derived from Lidar Depolarization
In Part II of this series of papers describing the results of the extended time observations of cirrus clouds from the University of Utah Facility for Atmospheric Remote Sensing (FARS), the information content of laser backscatter depolarization ...
Kenneth Sassen; Sally Benson
The Role of Ice Particle Shapes and Size Distributions in the Single Scattering Properties of Cirrus Clouds
The roles of ice particle size distributions (SDs) and particle shapes in cirrus cloud solar radiative transfer are investigated by analyzing SDs obtained from optical array probe measurements (particle sizes larger than 20�40 ?m) during ...
Andreas Macke; Peter N. Francis; Greg M. McFarquhar; Stefan Kinne
Cirrus Cloud Properties Derived from POLDER-1/ADEOS Polarized Radiances: First Validation Using a Ground-Based Lidar Network
Bidirectional polarized reflectances measured with the POLDER-1 instrument on board Advanced Earth Observing Satellite-1 have been used to infer cloud altitude and thermodynamical phase (ice/liquid) at a global scale. This paper presents a ...
H�l�ne Chepfer; Philippe Goloub; James Spinhirne; Pierre H. Flamant; Mario Lavorato; Laurent Sauvage; G�rard Brogniez; Jacques Pelon
The 27�28 October 1986 FIRE IFO Cirrus Case Study: Cloud Optical Properties Determined by High Spectral Resolution Lidar
During the FIRE cirrus IFO, the High Spectral Resolution Lidar (HSRL) was operated from a roof top site on the University of Wisconsin�Madison campus. Because the HSRL technique separately measures the molecular and cloud particle backscatter ...
C. J. Grund; E. W. Eloranta
Retrieval of cloud properties using CALIPSO Imaging Infrared Radiometer. Part II: effective diameter and ice water path
The paper describes the version 3 Level 2 operational analysis of the Imaging Infrared Radiometer (IIR) data collected in the framework of the CALIPSO mission to retrieve cirrus cloud effective diameter and ice water path in synergy with the ...
Anne Garnier; Jacques Pelon; Philippe Dubuisson; Ping Yang; Micha�l Faivre; Olivier Chomette; Nicolas Pascal; Pat Lucker; Tim Murray
Cirrus Cloud Microphysical Property Retrieval Using Lidar and Radar Measurements. Part I: Algorithm Description and Comparison with In Situ Data
A retrieval algorithm is described to estimate vertical profiles of cirrus-cloud ice water content (IWC) and general effective size Dge from combined lidar and radar measurements. In the algorithm, the lidar extinction coefficient ? is ...
A Prognostic Cloud Water Parameterization for Global Climate Models
An efficient new prognostic cloud water parameterization designed for use in global climate models is described. The scheme allows for life cycle effects in stratiform clouds and permits cloud optical properties to be determined interactively. ...
Anthony D. Del Genio; Mao-Sung Yao; William Kovari; Kenneth K-W. Lo
Solar Radiative Transfer in Clouds with Vertical Internal Inhomogeneity
To investigate the photon transport in inhomogeneous clouds, a Monte Carlo cloud model with internal variation of optical properties is developed. The data for cloud vertical internal inhomogeneity are chosen from published observations. ...
J. Li; D. J. W. Geldart; Petr Ch�lek
Aerosol Remote Sensing over Clouds Using A-Train Observations
The detection of aerosol above clouds is critical for the estimate of both the aerosol and cloud radiative impacts. In this study, the authors present a new method to retrieve the aerosol properties over clouds that uses the multiangle ...
F. Waquet; J. Riedi; L. C. Labonnote; P. Goloub; B. Cairns; J-L. Deuz�; D. Tanr�
The Albedo Field and Cloud Radiative Forcing Produced by a General Circulation Model with Internally Generated Cloud Optics
A spectral general circulation model (GCM) is run for perpetual January with fixed sea surface temperature conditions. It has internally generated, variable cloud optical properties as well as variable cloud arm and heights. The cloud optics are ...
Thomas P. Charlock; V. Ramanathan
Cloud Particle Phase Determination with the AVHRR
An accurate determination of cloud particle phase is required for the retrieval of other cloud properties from satellite and for radiative flux calculations in climate models. The physical principles underlying phase determination using the ...
Jeffrey R. Key; Janet M. Intrieri
Entrainment and Detrainment in Cumulus Clouds
Vertical redistribution of air and its properties inside convective clouds can be studied by standard thermodynamic analyses (Paluch and saturation point diagrams) if the clouds are nonprecipitating and ice free. It is shown from such analysis ...
Gregory R. Taylor; Marcia B. Baker
Stratocumulus Clouds
This paper reviews the current knowledge of the climatological, structural, and organizational aspects of stratocumulus clouds and the physical processes controlling them. More of Earth�s surface is covered by stratocumulus clouds than by any ...
Robert Wood
Cirrus Cloud Properties Derived from High Spectral Resolution Infrared Spectrometry during FIRE II. Part III: Ground-Based HIS Results
During FIRE II, cirrus clouds were observed in the wavelength range 3�19, �m with two High Resolution Interferometer Sounders as described in the Part I companion paper. One, known as AC-HIS, was mounted on the NASA ER-2 aircraft in order to look ...
A. D. Collard; S. A. Ackerman; W. L. Smith; X. Ma; H. E. Revercomb; R. O. Knuteson; S-C. Lee
Radiative Transfer in Cirrus Clouds. Part IV: On Cloud Geometry, Inhomogeneity, and Absorption
The effects of cloud geometry and inhomogeneity on the radiative properties of cirrus clouds are investigated by using the successive orders of scattering (SOS) approach for radiative transfer. This approach is an integral solution method that em ...
K. N. Liou; N. Rao
Simulations of Arctic mixed-phase clouds using a new aerosol-linked ice nuclei parameterization in a prognostic ice prediction scheme.
??Despite the nearly universally-accepted notion that the Arctic is one of the most important areas to fully understand in the face of a changing global� (more)
Carpenter, James Michael
Statistical cloud coverage as a function of cloud optical thickness
The time-averaged, daylight fractional statistical cloud coverages as a function of cloud optical thickness and selected values of cloud transmission were determined for various geographic areas using D1 data from the International Satellite Cloud Climatology Project (ISCCP). The regions of interest chosen for this report are: global earth, global sea, global land, global coast, and the six 30{degree}-latitude bands over sea, over land, and over coast with longitude 0{degree}--360{degree}. This statistical information is deduced from data determined from satellite measurements of terrestrial, atmospheric and cloud properties by the International Satellite Cloud Climatology Project. In particular the results are based on the ISCCP D1 data base.
Brower, K.L.
ARM - Measurement - Total cloud water
cloud water cloud water ARM Data Discovery Browse Data Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Measurement : Total cloud water The total concentration (mass/vol) of ice and liquid water particles in a cloud; this includes condensed water content (CWC). Categories Cloud Properties Instruments The above measurement is considered scientifically relevant for the following instruments. Refer to the datastream (netcdf) file headers of each instrument for a list of all available measurements, including those recorded for diagnostic or quality assurance purposes. External Instruments NCEPGFS : National Centers for Environment Prediction Global Forecast System Field Campaign Instruments CSI : Cloud Spectrometer and Impactor PDI : Phase Doppler Interferometer
ARM - Measurement - Cloud droplet size
droplet size droplet size ARM Data Discovery Browse Data Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Measurement : Cloud droplet size Linear size (e.g. radius or diameter) of a cloud particle Categories Cloud Properties Instruments The above measurement is considered scientifically relevant for the following instruments. Refer to the datastream (netcdf) file headers of each instrument for a list of all available measurements, including those recorded for diagnostic or quality assurance purposes. Field Campaign Instruments CPI : Cloud Particle Imager CVI-AIR : Counterflow Virtual Impactor MIRAI : JAMSTEC Research Vessel Mirai PDI : Phase Doppler Interferometer UAV-PROTEUS-MICRO : Proteus Cloud Microphysics Instruments SPEC-CPI : Stratton Park Engineering Company - Cloud particle imager
Cloud Chmabers
Video - (Requires Windows Media Player) Build your own cloud chamber - Instructions Project Contact: Tom Jordan Web Maintainer: firstname.lastname@example.com Last Update: May 31, 2011...
Distribution of Local Open-Circuit Voltage on Amorphous and Nanocrystalline Mixed-Phase Si:H and SiGe:H Solar Cells (Poster)
DOE Green Energy (OSTI)
By combining SKPM and AFM, they have developed a method to measure the local V{sub oc} distribution in mixed-phase solar cells. The results clearly show the nanocrystalline aggregation. The V{sub oc} is smaller in the nanocrystalline aggregates than in the surrounding amorphous matrix, and the transition from the low to high V{sub oc} is a gradual change. Although there are some lateral charge redistributions, a clear distinction between the amorphous and nanocrystalline regions has been observed. The current SKPM results and previous C-AFM results provide extra support for the two-diode model for explaining the carrier transport in the mixed-phase solar cells.
Jiang, C.-S.; Moutinho, H. R.; Al-Jassim, M. M.; Kazmerski, L. L.; Yan, B.; Yang, J.; Guha, S.
ARM - Evaluation Product - Cloud Classification VAP
properties includes cloud boundaries, thickness, phase, type, and precipitation information, and hence provides a useful tool for evaluation of model simulations and...
Cloud computing for dynamic systems
Cloud computing is a fast emerging model for enabling dynamic on-demand computing and IT-based services. It promotes dynamic properties and characteristics such as scalability, agility, flexibility, virtualised and distributed on-demand computing. However, ...
Khaled Sabry
ARM - Measurement - Cloud base height
base height base height ARM Data Discovery Browse Data Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Measurement : Cloud base height For a given cloud or cloud layer, the lowest level of the atmosphere where cloud properties are detectable. Categories Cloud Properties Instruments The above measurement is considered scientifically relevant for the following instruments. Refer to the datastream (netcdf) file headers of each instrument for a list of all available measurements, including those recorded for diagnostic or quality assurance purposes. ARM Instruments BLC : Belfort Laser Ceilometer MPL : Micropulse Lidar MWRP : Microwave Radiometer Profiler RL : Raman Lidar VCEIL : Vaisala Ceilometer External Instruments NOAASURF : NOAA Surface Meteorology Data, collected by NWS and NCDC
Distribution of Local Open-Circuit Voltage on Amorphous and Nanocrystalline Mixed-Phase Si:H and SiGe:H Solar Cells: Preprint
Local open-circuit voltage (Voc) distributions on amorphous and nanocrystalline mixed-phase silicon solar cells were measured using a scanning Kelvin probe microscope (SKPM) on the p layer of an n-i-p structure without the top ITO contact. During the measurement, the sample was illuminated with a laser beam that was used for the atomic force microscopy (AFM). Therefore, the surface potential measured by SKPM is the sum of the local Voc and the difference in workfunction between the p layer and the AFM tip. Comparing the SKPM and AFM images, we find that nanocrystallites aggregate in the amorphous matrix with an aggregation size of {approx}0.5 ..mu..m in diameter, where many nanometer-size grains are clustered. The Voc distribution shows valleys in the nanocrystalline aggregation area. The transition from low to high Voc regions is a gradual change within a distance of about 1 ..mu..m. The minimum Voc value in the nanocrystalline clusters in the mixed-phase region is larger than the Voc of a nc-Si:H single-phase solar cell. These results could be due to lateral photo-charge redistribution between the two phases. We have also carried out local Voc measurements on mixed-phase SiGe:H alloy solar cells. The magnitudes of Voc in the amorphous and nanocrystalline regions are consistent with the J-V measurements.
Jiang, C.-S.; Moutinho, H. R.; Al-Jassim, M. M.; Kazmerski, L. L.; Yan, B.; Owens, J. M.; Yang, J.; Guha, S.
Cellular clouds
This paper progresses an analysis of what it means to be a cellular network operator and what form the ownership and control of future cellular networks may take. Alternative modes of ownership may allow for the creation of more flexible cellular networking ... Keywords: Cellular Cloud, Cellular network, Cloud Computing, Cognitive radio, DSA, LTE, MVNO, Services, Utility Cellular Network
Tim Forde; Linda Doyle
Comparison of Airborne In Situ, Airborne Radar�Lidar, and Spaceborne Radar�Lidar Retrievals of Polar Ice Cloud Properties Sampled during the POLARCAT Campaign
This study illustrates the high potential of RALI, the French airborne radar�lidar instrument, for studying cloud processes and evaluating satellite products when satellite overpasses are available. For an Arctic nimbostratus ice cloud collected ...
Julien Delano�; Alain Protat; Olivier Jourdan; Jacques Pelon; Mathieu Papazzoni; R�gis Dupuy; Jean-Francois Gayet; Caroline Jouan
Environmental control of cloud-to-ground lightning polarity in severe storms
In this study, it is hypothesized that the mesoscale environment can indirectly control the cloud-to-ground (CG) lightning polarity of severe storms by directly affecting their structural, dynamical, and microphysical properties, which in turn directly control cloud electrification and CG flash polarity. A more specific hypothesis, which has been supported by past observational and laboratory charging studies, suggests that broad, strong updrafts and associated large liquid water contents in severe storms lead to enhanced positive charging of graupel and hail via the noninductive charging mechanism, the generation of an inverted charge structure, and increased positive CG lightning production. The corollary is that environmental conditions favoring these kinematic and microphysical characteristics should support severe storms generating an anomalously high (> 25%) percentage of positive CG lightning (i.e., positive storms), while environmental conditions relatively less favorable should sustain storms characterized by a typical (? 25%) percentage of positive CG lightning (i.e., negative storms). Forty-eight inflow proximity soundings were analyzed to characterize the environments of nine distinct mesoscale regions of severe storms (four positive and five negative) on six days during May � June 2002 over the central United States. This analysis clearly demonstrated significant and systematic differences in the mesoscale environments of positive and negative storms, which were consistent with the stated hypothesis. When compared to negative storms, positive storms occurred in environments associated with a drier low to midtroposphere, higher cloud base height, smaller warm cloud depth, stronger conditional instability, larger 0-3 km AGL wind shear, stronger 0-2 km AGL storm-relative wind speed, and larger buoyancy in the mixed-phase zone, at a statistically significant level. Differences in the warm cloud depth of positive and negative storms were by far the most dramatic, suggesting an important role for this parameter in controlling CG lightning polarity. Subjective visual inspection of radar imagery revealed no strong relationship between convective mode and CG lightning polarity, and also illustrated that positive and negative severe storms can be equally intense.
Buffalo, Kurt Matthew
In this study, it is hypothesized that the mesoscale environment can indirectly control the cloud-to-ground (CG) lightning polarity of severe storms by directly affecting their structural, dynamical, and microphysical properties, which in turn directly control cloud electrification and CG flash polarity. A more specific hypothesis, which has been supported by past observational and laboratory charging studies, suggests that broad, strong updrafts and associated large liquid water contents in severe storms lead to enhanced positive charging of graupel and hail via the noninductive charging mechanism, the generation of an inverted charge structure, and increased positive CG lightning production. The corollary is that environmental conditions favoring these kinematic and microphysical characteristics should support severe storms generating an anomalously high (> 25%) percentage of positive CG lightning (i.e., positive storms), while environmental conditions relatively less favorable should sustain storms characterized by a typical (? 25%) percentage of positive CG lightning (i.e., negative storms). Forty-eight inflow proximity soundings were analyzed to characterize the environments of nine distinct mesoscale regions of severe storms (four positive and five negative) on six days during May - June 2002 over the central United States. This analysis clearly demonstrated significant and systematic differences in the mesoscale environments of positive and negative storms, which were consistent with the stated hypothesis. When compared to negative storms, positive storms occurred in environments associated with a drier low to midtroposphere, higher cloud base height, smaller warm cloud depth, stronger conditional instability, larger 0-3 km AGL wind shear, stronger 0-2 km AGL storm-relative wind speed, and larger buoyancy in the mixed-phase zone, at a statistically significant level. Differences in the warm cloud depth of positive and negative storms were by far the most dramatic, suggesting an important role for this parameter in controlling CG lightning polarity. Subjective visual inspection of radar imagery revealed no strong relationship between convective mode and CG lightning polarity, and also illustrated that positive and negative severe storms can be equally intense.
Cirrus Cloud Radiative and Microphysical Properties from Ground Observations and In Situ Measurements during FIRE 1991 and Their Application to Exhibit Problems in Cirrus Solar Radiative Transfer Modeling
Measurements from the FIRE 1991 cirrus cloud field experiment in the central United States are presented and analyzed.
S. Kinne; T. P. Ackerman; M. Shiobara; A. Uchiyama; A. J. Heymsfield; L. Miloshevich; J. Wendell; E. Eloranta; C. Purgold; R. W. Bergstrom
Hierarchical Diagnosis J. T. Kiehl, M. W. Moncrieff, J. J. Hack...
model and the cumulus ensemble model, the radiative properties of liquid, mixed phase and ice clouds are parameterized by using the NCAR CCM2 radiation code in...
ARM - Selected Science Team Applications - FY 2009
University: "Ice Nuclei Relation to Aerosol Properties: Data Analysis and Model Parameterization for IN in Mixed-Phase Clouds" Dr. David Randall, Colorado State University:...
Possible Aerosol Effects on Ice Clouds via Contact Nucleation
The indirect effect of aerosols on water clouds, whereby aerosol particles change cloud optical properties, is caused by aerosol-induced changes of the size and number of cloud droplets. This affects the lifetime of the water clouds as well as ...
Ulrike Lohmann
ARM - Field Campaign - Spring Cloud IOP
govCampaignsSpring Cloud IOP govCampaignsSpring Cloud IOP Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Campaign : Spring Cloud IOP 2000.03.01 - 2000.03.26 Lead Scientist : Gerald Mace For data sets, see below. Summary The Atmospheric Radiation Measurement (ARM) Program conducted a Cloud Intensive Operational Period (IOP) in March 2000 that was the first-ever effort to document the 3-dimensional cloud field from observational data. Prior numerical studies of solar radiation propagation through the atmosphere in the presence of clouds have been limited by the necessity to use theoretical representations of clouds. Three-dimensional representations of actual clouds and their microphysical properties, such as the distribution of ice and water, had previously not been possible
We present the 1.1 mm Bolocam Galactic Plane Survey (BGPS) observations of the Gemini OB1 molecular cloud complex, and targeted NH{sub 3} observations of the BGPS sources. When paired with molecular spectroscopy of a dense gas tracer, millimeter observations yield physical properties such as masses, radii, mean densities, kinetic temperatures, and line widths. We detect 34 distinct BGPS sources above 5{sigma} = 0.37 Jy beam{sup -1} with corresponding 5{sigma} detections in the NH{sub 3}(1,1) transition. Eight of the objects show water maser emission (20%). We find a mean millimeter source FWHM of 1.12 pc and a mean gas kinetic temperature of 20 K for the sample of 34 BGPS sources with detections in the NH{sub 3}(1,1) line. The observed NH{sub 3} line widths are dominated by non-thermal motions, typically found to be a few times the thermal sound speed expected for the derived kinetic temperature. We calculate the mass for each source from the millimeter flux assuming the sources are isothermal and find a mean isothermal mass within a 120'' aperture of 230 {+-} 180 M{sub sun}. We find a total mass of 8400 M{sub sun} for all BGPS sources in the Gemini OB1 molecular cloud, representing 6.5% of the cloud mass. By comparing the millimeter isothermal mass to the virial mass calculated from the NH{sub 3} line widths within a radius equal to the millimeter source size, we find a mean virial parameter (M{sub vir}/M {sub iso}) of 1.0 {+-} 0.9 for the sample. We find mean values for the distributions of column densities of 1.0 x 10{sup 22} cm{sup -2} for H{sub 2}, and 3.0 x 10{sup 14} cm{sup -2} for NH{sub 3}, giving a mean NH{sub 3} abundance of 3.0 x 10{sup -8} relative to H{sub 2}. We find volume-averaged densities on the order of 10{sup 3}-10{sup 4} cm{sup -3}. The sizes and densities suggest that in the Gem OB1 region the BGPS is detecting the clumps from which stellar clusters form, rather than smaller, higher density cores where single stars or small multiple systems form.
Dunham, Miranda K.; Evans, Neal J.; Harvey, Paul; Merello, Manuel [Department of Astronomy, The University of Texas at Austin, 1 University Station C1400, Austin, TX 78712-0259 (United States); Rosolowsky, Erik [University of British Columbia, Okanagan, 3333 University Way, Kelowna BC V1V 1V7 (Canada); Cyganowski, Claudia J. [Department of Astronomy, University of Wisconsin, Madison, WI 53706 (United States); Aguirre, James [Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104 (United States); Bally, John; Battersby, Cara; Ginsburg, Adam; Glenn, Jason; Stringfellow, Guy S. [CASA, University of Colorado, 389-UCB, Boulder, CO 80309 (United States); Bradley, Eric Todd [Department of Physics, University of Central Florida, 4000 Central Florida Boulevard, Orlando, FL 32816-2385 (United States); Dowell, Darren [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91104 (United States); Drosback, Meredith [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904 (United States); Schlingman, Wayne; Shirley, Yancy L. [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Walawender, Josh [Institute for Astronomy, University of Hawaii, 640 N. Aohoku Place, Hilo, HI 96720 (United States); Williams, Jonathan P., E-mail: email@example.com [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)
ARM - Measurement - Cloud condensation nuclei
condensation nuclei condensation nuclei ARM Data Discovery Browse Data Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Measurement : Cloud condensation nuclei Small particles (typically 0.0002 mm, or 1/100 th the size of a cloud droplet) about which cloud droplets coalesce. Categories Aerosols, Cloud Properties Instruments The above measurement is considered scientifically relevant for the following instruments. Refer to the datastream (netcdf) file headers of each instrument for a list of all available measurements, including those recorded for diagnostic or quality assurance purposes. ARM Instruments AOS : Aerosol Observing System CCN : Cloud Condensation Nuclei Particle Counter Field Campaign Instruments AOS : Aerosol Observing System
ARM - Measurement - Cloud ice particle
ice particle ice particle ARM Data Discovery Browse Data Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Measurement : Cloud ice particle Particles made of ice found in clouds. Categories Cloud Properties Instruments The above measurement is considered scientifically relevant for the following instruments. Refer to the datastream (netcdf) file headers of each instrument for a list of all available measurements, including those recorded for diagnostic or quality assurance purposes. ARM Instruments MET : Surface Meteorological Instrumentation Field Campaign Instruments REPLICATOR : Balloon-borne Ice Crystal Replicator CPI : Cloud Particle Imager CVI-AIR : Counterflow Virtual Impactor LEARJET : Lear Jet PARTIMG : Particle imager UAV-PROTEUS-MICRO : Proteus Cloud Microphysics Instruments
In Situ Cloud Sensing with Multiple Scattering Lidar: Simulations and Demonstration
Due to the spatially inhomogeneous nature of clouds there are large uncertainties in validating remote sensing retrievals of cloud properties with traditional in situ cloud probes, which have sampling volumes measured in liters. This paper ...
K. Franklin Evans; R. Paul Lawson; Pat Zmarzly; Darren O'Connor; Warren J. Wiscombe
Polarization Lidar at Summit, Greenland for the Detection of Cloud Phase and Particle Orientation
Accurate measurements of cloud properties are necessary to document the full range of cloud conditions and characteristics. The Cloud, Aerosol Polarization and Backscatter Lidar (CAPABL) has been developed to address this need by measuring ...
Ryan R. Neely III; Matthew Hayman; Robert Stillwell; Jeffrey P. Thayer; R. Michael Hardesty; Michael O�Neill; Matthew D. Shupe; Catherine Alvarez
Polarization Lidar at Summit, Greenland, for the Detection of Cloud Phase and Particle Orientation
Ryan R. Neely III; Matthew Hayman; Robert Stillwell; Jeffrey P. Thayer; R. Michael Hardesty; Michael O'Neill; Matthew D. Shupe; Catherine Alvarez
Pre-Cloud Aerosol, Cloud Droplet Concentration, and Cloud Condensation Nuclei from the VAMOS Ocean-Cloud-Atmosphere Land Study (VOCALS) Field Campaign First Quarter 2010 ASR Program Metric Report
In this, the first of a series of Program Metric Reports, we (1) describe archived data from the DOE G-1 aircraft, (2) illustrate several relations between sub-cloud aerosol, CCN, and cloud droplets pertinent to determining the effects of pollutant sources on cloud properties, and (3) post to the data archive an Excel spreadsheet that contains cloud and corresponding sub-cloud data.
Kleinman, LI; Springston, SR; Daum, PH; Lee, Y-N; Sedlacek, AJ; Senum, G; Wang, J
Particle-resolved simulation of aerosol size, composition, mixing state, and the associated optical and cloud condensation nuclei activation properties in an evolving urban plume
The recently developed particle-resolved aerosol box model PartMC-MOSAIC was used to simulate the evolution of aerosol mixing state and the associated optical and cloud condensation nuclei (CCN) activation properties in an idealized urban plume. The model explicitly resolved the size and composition of individual particles from a number of sources and tracked their evolution due to condensation/evaporation, coagulation, emission, and dilution. The ensemble black carbon (BC) specific absorption cross section increased by 40% over the course of two days as a result of BC aging by condensation and coagulation. Three- and four-fold enhancements in CCN/CN ratios were predicted to occur within 6 hours for 0.2% and 0.5% supersaturations (S), respectively. The particle-resolved results were used to evaluate the errors in the optical and CCN activation properties that would be predicted by a conventional sectional framework that assumes monodisperse, internally-mixed particles within each bin. This assumption artificially increased the ensemble BC specific absorption by 14-30% and decreased the single scattering albedo by 0.03-0.07 while the bin resolution had a negligible effect. In contrast, the errors in CCN/CN ratios were sensitive to the bin resolution, and they depended on the chosen supersaturation. For S = 0.2%, the CCN/CN ratio predicted using 100 internally-mixed bins was up to 25% higher than the particle-resolved results, while it was up to 125% higher using 10 internally-mixed bins. Errors introduced in the predicted optical and CCN properties by neglecting coagulation were also quantified.
Zaveri, Rahul A.; Barnard, James C.; Easter, Richard C.; Riemer, Nicole; West, Matthew
Cloud computing beyond objects: seeding the cloud
Cloud computing is an emerging computing milieu which dynamically enables scalable and virtually unlimited resources. This panel will discuss emerging tools, skills and technologies that will ""seed the cloud"" - enabling improved interoperability, security, ... Keywords: cloud computing, skills, technologies, tools
Steven Fraser; Robert Biddle; Scott Jordan; Kate Keahey; Bob Marcus; E. Michael Maximilien; Dave Thomas
The Bolocam Galactic Plane Survey -- III. Characterizing Physical Properties of Massive Star-Forming Regions in the Gemini OB1 Molecular Cloud
We present the 1.1 millimeter Bolocam Galactic Plane Survey (BGPS) observations of the Gemini OB1 molecular cloud complex, and targeted ammonia observations of the BGPS sources. When paired with molecular spectroscopy of a dense gas tracer, millimeter observations yield physical properties such as masses, radii, mean densities, kinetic temperatures and line widths. We detect 34 distinct BGPS sources above 5-sigma=0.37 Jy/beam with corresponding 5-sigma detections in the ammonia (1,1) transition. Eight of the objects show water maser emission (20%). We find a mean millimeter source FWHM of 1.12 pc, and a mean kinetic temperature of 20 K for the sample of 34 BGPS sources. The observed ammonia line widths are dominated by non-thermal motions, typically found to be a few times the thermal sound speed expected for the derived kinetic temperature. We calculate the mass for each source from the millimeter flux assuming the sources are isothermal and find a mean isothermal mass within a 120" aperture of 230 +/- 180 s...
Dunham, Miranda K; Evans, Neal J; Cyganowski, Claudia J; Aguirre, James; Bally, John; Battersby, Cara; Bradley, Eric Todd; Dowell, Darren; Drosback, Meredith; Ginsburg, Adam; Glenn, Jason; Harvey, Paul; Merello, Manuel; Schlingman, Wayne; Shirley, Yancy L; Stringfellow, Guy S; Walawender, Josh; Williams, Jonathan P
Bulk Scattering Properties for the Remote Sensing of Ice Clouds. Part III: High-Resolution Spectral Models from 100 to 3250 cm?1
This study reports on the development of bulk single-scattering models for ice clouds that are appropriate for use in hyperspectral radiative transfer cloud modeling over the spectral range from 100 to 3250 cm?1. The models are developed in a ...
Bryan A. Baum; Ping Yang; Shaima Nasiri; Andrew K. Heidinger; Andrew Heymsfield; Jun Li
ARM - Measurement - Cloud particle size distribution
size distribution size distribution ARM Data Discovery Browse Data Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Measurement : Cloud particle size distribution The number of cloud particles present in any given volume of air within a specified size range, including liquid and ice. Categories Cloud Properties Instruments The above measurement is considered scientifically relevant for the following instruments. Refer to the datastream (netcdf) file headers of each instrument for a list of all available measurements, including those recorded for diagnostic or quality assurance purposes. ARM Instruments WSACR : Scanning ARM Cloud Radar, tuned to W-Band (95GHz) Field Campaign Instruments CPI : Cloud Particle Imager CLDAEROSMICRO : Cloud and Aerosol Microphysical Properties
Aerosol First Indirect Effects on Non-Precipitating Low-Level Liquid Cloud Properties as Simulated by CAM5 at ARM Sites
We quantitatively examine the aerosol first indirect effects (FIE) for non-precipitating low-level single-layer liquid phase clouds simulated by the Community Atmospheric Model version 5 (CAM5) running in the weather forecast mode at three DOE Atmospheric Radiation Measurement (ARM) sites. The FIE is quantified in terms of a relative change in cloud droplet effective radius for a relative change in aerosol accumulation mode number concentration under conditions of fixed liquid water content (LWC). CAM5 simulates aerosol-cloud interactions reasonably well for this specific cloud type, and the simulated FIE is consistent with the long-term observations at the examined locations. The FIE in CAM5 generally decreases with LWC at coastal ARM sites, and is larger by using cloud condensation nuclei rather than aerosol accumulation mode number concentration as the choice of aerosol amount. However, it has no significant variations with location and has no systematic strong seasonal variations at examined ARM sites.
Zhao, Chuanfeng; Klein, Stephen A.; Xie, Shaocheng; Liu, Xiaohong; Boyle, James; Zhang, Yuying
Z .Atmospheric Research 57 2001 5180 www.elsevier.comrlocateratmos
2 , depending on the ice habit. It is also shown that mixed-phase clouds are more sensitive; Radiation budget; Ice optical properties; Mixed phase ) Corresponding author. Tel.: q1-814-863-1584; fax: q1 for the parameterization of cloud optical properties in bulk and bin microphysical models. Implications for arctic cloudy
Harrington, Jerry Y.
Foundations for Statistical-Physical Precipitation Retrieval from Passive Microwave Satellite Measurements. Part I: Brightness-Temperature Properties of a Time-dependent Cloud-Radiation Model
A cloud-radiation model is used to investigate the relationship between emerging microwave brightness temperatures (TB's) and vertically distributed mixtures of liquid and frozen hydrometeors as a means to establish the framework for a hybrid ...
Eric A. Smith; Harry J. Cooper; Xuwu Xiang; Alberto Mugnai; Gregory J. Tripoli
Evaluation of Hydrometeor Phase and Ice Properties in Cloud-Resolving Model Simulations of Tropical Deep Convection Using Radiance and Polarization Measurements
Satellite measurements are used to evaluate the glaciation, particle shape, and effective radius in cloud-resolving model simulations of tropical deep convection. Multidirectional polarized reflectances constrain the ice crystal geometry and the ...
Bastiaan van Diedenhoven; Ann M. Fridlind; Andrew S. Ackerman; Brian Cairns
Information Content and Uncertainties in Thermodynamic Profiles and Liquid Cloud Properties Retrieved from the Ground-Based Atmospheric Emitted Radiance Interferometer (AERI)
The Atmospheric Emitted Radiance Interferometer (AERI) observes spectrally resolved downwelling radiance emitted by the atmosphere in the infrared portion of the electromagnetic spectrum. Profiles of temperature and water vapor, and cloud liquid ...
D.D. Turner; U. L�hnert
The Impact of Ice Crystal Shapes, Size Distributions, and Spatial Structures of Cirrus Clouds on Solar Radiative Fluxes
The solar radiative properties of cirrus clouds depend on ice particle shape, size, and orientation, as well as on the spatial cloud structure. Radiation schemes in atmospheric circulation models rely on estimates of cloud optical thickness only. ...
I. Schlimme; A. Macke; J. Reichardt
Clouds as Seen by Satellite Sounders (3I) and Imagers (ISCCP). Part III: Spatial Heterogeneity and Radiative Effects
Their relatively good spectral resolution makes infrared sounders very useful for the determination of cloud properties (day and night), and their coarse spatial resolution has less effect on clouds with large spatial extents like cirrus clouds. ...
C. J. Stubenrauch; W. B. Rossow; N. A. Scott; A. Ch�din
A Scheme for Parameterizing Ice-Cloud Water Content in General Circulation Models
The optical properties of ice clouds are a primary issue for climate and climate change. Evaluating these optical properties in three-dimensional models for studying climate will require a method to calculate the ice water content of such clouds. ...
Andrew J. Heymsfield; Leo J. Donner
Erroneous Relationships among Humidity and Cloud Forcing Variables in Three Global Climate Models
Links are examined between time-averaged cloud radiative properties, particularly the longwave and shortwave components of cloud radiative forcing (CRF), and properties of the long-term averages of atmospheric soundings, in particular upper-...
Florian Bennhold; Steven Sherwood
Cloud Computing Operations Research
This paper argues that the cloud computing industry faces many decision problems where operations research OR could add tremendous value. To this end, we provide an OR perspective on cloud computing in three ways. First, we compare the cloud computing ... Keywords: cloud IT, cloud computing, green IT, operations research, supply chain
Ilyas Iyoob, Emrah Zarifoglu, A. B. Dieker
Chemical and Physical Properties of Atmospheric Aerosols (a) A Case Study in the Unique Properties of Agricultural Aerosols (b) The Role of Chemical Composition in Ice Nucleation during the Arctic Spring
This study focuses on the analysis of atmospheric particles sampled from two different field campaigns: the field study at a cattle feeding facility in the summer from 2005 to 2008 and the Indirect and Semi-Direct Aerosol Campaign (ISDAC) in 2008. A ground site field study at a representative large cattle feeding facility in the Texas Panhandle was conducted to characterize the particle size distributions, hygroscopicity, and chemical composition of agricultural aerosols. Here, a first comprehensive dataset is reported for these physical and chemical properties of agricultural aerosols appropriate for use in a site-specific emission inventory. The emission rate and transport of the aerosols are also discussed. In addition, mixing ratios of total and gaseous ammonia were measured at the same field in 2007 and 2008. Measurements such as these provide a means to determine whether the fugitive dust emitted from a typical large feedlot represents a health concern for employees of the feeding operation and the nearby community. Detailed chemical composition of aircraft-sampled particles collected during ISDAC was studied. Filter samples were collected under a variety of conditions in and out of mixed phase and ice clouds in the Arctic. Specifically, particles were sampled from a mixed-phase cloud during a period of observed high concentrations of ice nuclei (IN), a biomass plume, and under relatively clean ambient conditions. Composition of particles was studied on a particle-by-particle basis using several microspectroscopy techniques. Based on the elemental composition analysis, more magnesium was found in Arctic cloud residues relative to ambient air. Likewise, based on the carbon speciation analysis, high IN samples contained coated inorganics, carbonate, and black or brown carbon particles. In the samples collected during a flight through a biomass burning plume, water-soluble organic carbon was the dominant overall composition. Due to their hygroscopic nature, these organics may preferably act as cloud condensation nuclei (CCN) rather than IN. Other ambient samples contained relatively higher fractions of organic and inorganic mixtures and less purely water-soluble organics than found in the biomass particles. The most likely source of inorganics would be sea salt. When present, sea salt may further enhance ice nucleation.
Moon, Seong-Gi
Observations of the Madden Julian Oscillation for Cloud Modeling...
Manus MJO IOP * Scientific Focus - What are the primary cloud, precipitation, and thermodynamic property differences between the active and suppressed phases of the MJO,...
Cloud Condensation Nuclei
The state of knowledge of the particles upon which liquid droplets condense to form atmospheric water clouds is presented. The realization of cloud condensation nuclei (CCN) as a distinct aerosol subset originated with the cloud microphysical ...
James G. Hudson
Forecasting of Supercooled Clouds
Using parameterizations of cloud microphysics, a technique to forecast supercooled cloud events is suggested. This technique can be coupled on the mesoscale with a prognostic equation for cloud water to improve aircraft icing forecasts. The ...
Andr� Tremblay; Anna Glazer; Wanda Szyrmer; George Isaac; Isztar Zawadzki
Nailing Down Ice in a Cloud Model
Nailing Down Ice in a Cloud Model Nailing Down Ice in a Cloud Model For original submission and image(s), see ARM Research Highlights http://www.arm.gov/science/highlights/ Research Highlight A research team led by scientists at Pacific Northwest National Laboratory identified specific strengths and weaknesses of four different ice cloud retrieval algorithms. Their comparisons tested the ability of the algorithms to obtain cloud properties from radar and lidar observational measurements. The team noted the sometimes large variances in heating/cooling measurements compared to the observed data. Identifying specific weaknesses will help scientists improve our understanding of cloud properties in the atmosphere, which can be used for climate model development and evaluation. "Measuring the effective size and mass of ice crystals impacts our understanding
Stratocumulus Cloud Field Reflected Fluxes: The Effect of Cloud Shape
Reflected fluxes are calculated for stratocumulus cloud fields as a function of sky cover, cloud aspect ratio, and cloud shape. Cloud liquid water volume is held invariant as cloud shape is varied so that the results can be utilized more ...
R. M. Welch; B. A. Wielicki
Glossary Term - Cloud Chamber
Ceres Previous Term (Ceres) Glossary Main Index Next Term (Composition of the Earth's Atmosphere) Composition of theEarth's Atmosphere Cloud Chamber A cloud chamber showing the...
Precipitating clouds
or virga An multiple sensor based approach to provide water phase as well as ice phase properties Measurements - MWR - MPL or Raman lidar - MMCR The approach Water...
The Retrieval of Marine Stratiform Cloud Properties from Multiple Observations in the 3.9-�m Window under Conditions of Varying Solar Illumination
Radiometric observations in the 3.9-�m region have been used by a number of investigators for the determination of cloud parameters or sea surface temperature at night. Only a few attempts have been made to perform quantitative assessments of ...
Thomas J. Kleespies
ARM - Measurement - Cloud optical depth
optical depth optical depth ARM Data Discovery Browse Data Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Measurement : Cloud optical depth Amount of light cloud droplets or ice particles prevent from passing through a column of atmosphere. Categories Cloud Properties Instruments The above measurement is considered scientifically relevant for the following instruments. Refer to the datastream (netcdf) file headers of each instrument for a list of all available measurements, including those recorded for diagnostic or quality assurance purposes. External Instruments GOES : Geostationary Operational Environmental Satellites Field Campaign Instruments EC-CONVAIR580-BULK : Environment Canada Convair 580 Bulk Parameters GOES : Geostationary Operational Environmental Satellites
Evaluation of the Hydrometeor Layers in the East and West Pacific Within ISCCP Cloud Top Pressure-Optical Depth Bins Using Merged CloudSat and CALIPSO Data
ISCCP provides a multi-decadal and global description of cloud properties that are often grouped into joint histograms of column visible optical depth (?) and effective cloud top pressure (Ptop). It has not been possible until recently to know the ...
Gerald G. Mace; Forrest J. Wrenn
Global Simulations of Ice nucleation and Ice Supersaturation with an Improved Cloud Scheme in the Community Atmosphere Model
A process-based treatment of ice supersaturation and ice-nucleation is implemented in the National Center for Atmospheric Research (NCAR) Community Atmosphere Model (CAM). The new scheme is designed to allow (1) supersaturation with respect to ice, (2) ice nucleation by aerosol particles and (3) ice cloud cover consistent with ice microphysics. The scheme is implemented with a 4-class 2 moment microphysics code and is used to evaluate ice cloud nucleation mechanisms and supersaturation in CAM. The new model is able to reproduce field observations of ice mass and mixed phase cloud occurrence better than previous versions of the model. Simulations indicate heterogeneous freezing and contact nucleation on dust are both potentially important over remote areas of the Arctic. Cloud forcing and hence climate is sensitive to different formulations of the ice microphysics. Arctic radiative fluxes are sensitive to the parameterization of ice clouds. These results indicate that ice clouds are potentially an important part of understanding cloud forcing and potential cloud feedbacks, particularly in the Arctic.
Gettelman, A.; Liu, Xiaohong; Ghan, Steven J.; Morrison, H.; Park, Sungsu; Conley, Andrew; Klein, Stephen A.; Boyle, James; Mitchell, David; Li, J-L F.
Month-Long 2D Cloud-Resolving Model Simulation and Resultant Statistics of Cloud Systems Over the ARM SGP
Month-Long 2D Cloud-Resolving Model Simulation Month-Long 2D Cloud-Resolving Model Simulation and Resultant Statistics of Cloud Systems Over the ARM SGP X. Wu Department of Geological and Atmospheric Sciences Iowa State University Ames, Iowa X.-Z. Liang Illinois State Water Survey University of Illinois Urbana-Champaign, Illinois Introduction The cloud-resolving model (CRM) has recently emerged as a useful tool to develop improved representations of convections, clouds, and cloud-radiation interactions in general circulation models (GCMs). In particular, the fine spatial resolution allows the CRM to more realistically represent the detailed structure of cloud systems, including cloud geometric and radiative properties. The CRM simulations thus provide unique and comprehensive datasets, based on which more realistic GCM
Modeling of Submillimeter Passive Remote Sensing of Cirrus Clouds
The scattering properties of cirrus clouds at submillimeter-wave frequencies are analyzed and characterized in this paper. This study lays a theoretical foundation for using radiometric measurements to investigate and monitor cirrus properties ...
K. Franklin Evans; Steven J. Walter; Andrew J. Heymsfield; Merritt N. Deeter
Antarctic Cloud Radiative Forcing at the Surface Estimated from the AVHRR Polar Pathfinder and ISCCP D1 Datasets, 1985�93
Surface cloud radiative forcing from the newly extended Advanced Very High Resolution Radiometer (AVHRR) Polar Pathfinder (APP-x) dataset and surface cloud radiative forcing calculated using cloud and surface properties from the International ...
Michael J. Pavolonis; Jeffrey R. Key
Continental Liquid-phase Stratus Clouds at SGP: Meteorological Influences
Continental Liquid-phase Stratus Clouds at SGP: Meteorological Influences Continental Liquid-phase Stratus Clouds at SGP: Meteorological Influences and Relationship to Adiabacity Kim, Byung-Gon Kangnung National University Schwartz, Stephen Brookhaven National Laboratory Miller, Mark Brookhaven National Laboratory Min, Qilong State University of New York at Albany Category: Cloud Properties The microphysical properties of continental stratus clouds observed over SGP appear to be substantially influenced by micrometeorological conditions, such as static stability and updraft velocity. These influences may contribute to the observed weak correlation of aerosol light scattering coefficient with cloud-drop effective radius [Kim et al., JGR, 2003], although aerosol light scattering coefficient is not necessarily the most suitable surrogate aerosol property for number concentration of cloud
Microsoft PowerPoint - ARMST2006_mp.ppt
Characterization of Arctic Characterization of Arctic Mixed-Phase Clouds Matthew D. Shupe a , Pavlos Kollias b , Ed Luke b a Cooperative Institute for Research in Environmental Sciences - University of Colorado and NOAA/ESRL/PSD and b Brookhaven National Laboratory, Atmospheric Science Division, Upton, NY Mixed-Phase Cloud Properties Cloud Occurrence. Mixed-phase clouds occur 45% +/- 10% of the time per year at the NSA site. There is a marked increase in mixed-phase cloudiness in the spring and fall transition seasons, mostly at heights below about 1 km. All mixed-phase cloud properties presented in this panel were derived from MMCR and MWR measurements at the NSA site for the time period of March 1998 through December 2004. The statistics in all plots cover this full time period. Microphysical
Intercomparison of Cloud Imagery from the DMSP OLS, NOAA AVHRR, GOES VISSR, and Landsat MSS
Concurrent visible and infrared imagery from four satellite sensors (DMSP OLS, NOAA AVHRR, GOES VISSR, Landsat MSS) have been intercompared. Inherent differences in observed cloud properties and cloud field analyses are noted due to individual ...
R. G. Isaacs; J. C. Barnes
Climatology of Warm Boundary Layer Clouds at the ARM SGP Site and Their Comparison to Models
A 4-yr climatology (1997�2000) of warm boundary layer cloud properties is developed for the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) Program Southern Great Plains (SGP) site. Parameters in the climatology include cloud ...
Manajit Sengupta; Eugene E. Clothiaux; Thomas P. Ackerman
Sources of Error in Dual-Wavelength Radar Remote Sensing of Cloud Liquid Water Content
Dual-wavelength ratio (DWR) techniques offer the prospect of producing high-resolution mapping of cloud microphysical properties, including retrievals of cloud liquid water content (LWC) from reflectivity measured by millimeter-wavelength radars. ...
John K. Williams; J. Vivekanandan
Homogeneous Ice Nucleation and Supercooled Liquid Water in Orographic Wave Clouds
This study investigates ice nucleation mechanisms in cold lenticular wave clouds, a cloud type characterized by quasi-steady-state air motions and microphysical properties. It is concluded that homogeneous ice nucleation is responsible for the ...
Andrew J. Heymsfield; Larry M. Miloshevich
Influence of Cirrus Clouds on Weather and Climate Processes: A Global Perspective
Current understanding and knowledge of the composition and structure of cirrus clouds are reviewed and documented in this paper. In addition, the radiative properties of cirrus clouds as they relate to weather and climate processes are described ...
Kuo-Nan Liou
Calculating Monthly Radiative Fluxes and Heating Rates fromMonthly Cloud Observations
The radiative transfer model from NCAR�s general circulation model CCM3 is modified to calculate monthly radiative fluxes and heating rates from monthly observations of cloud properties from the International Satellite Cloud Climatology Project ...
John W. Bergman; Harry H. Hendon
Gazing at Cirrus Clouds for 25 Years through a Split Window. Part I: Methodology
This paper demonstrates that the split-window approach for estimating cloud properties can improve upon the methods commonly used for generating cloud temperature and emissivity climatologies from satellite imagers. Because the split-window ...
Andrew K. Heidinger; Michael J. Pavolonis
Retrieval of Surface Solar Radiation Budget under Ice Cloud Sky: Uncertainty Analysis and Parameterization
This study investigates and accounts for the influence of various ice cloud parameters on the retrieval of the surface solar radiation budget (SSRB) from reflected flux at the top of the atmosphere (TOA). The optical properties of ice clouds ...
Ying Zhang; Zhanqing Li; Andreas Macke
The Plane-Parallel Albedo Bias of Liquid Clouds from MODIS Observations
The authors present the global plane-parallel shortwave albedo bias of liquid clouds for two months, July 2003 and January 2004. The cloud optical properties necessary to perform the bias calculations come from the operational Moderate Resolution ...
Lazaros Oreopoulos; Robert F. Cahalan; Steven Platnick
The Prospect for Remote Sensing of Cirrus Clouds with a Submillimeter-Wave Spectrometer
Given the substantial radiative effects of cirrus clouds and the need to validate cirrus cloud mass in climate models, it is important to measure the global distribution of cirrus properties with satellite remote sensing. Existing cirrus remote ...
K. Franklin Evans; Aaron H. Evans; Ira G. Nolt; B. Thomas Marshall
Another Look at the Influence of Absorbing Aerosols in Drops on Cloud Absorption: Large Aerosols
Since as early as 1969, solar absorbing aerosols inside of cloud drops have been suggested to influence cloud radiative properties. The absorbing aerosols were invoked to help explain two �anomalies�: 1) the maximum visible albedo of thick ...
Carynelisa Erlick; Dana Schlesinger
3D Atmospheric Radiative Transfer for Cloud System-Resolving Models: Forward Modelling and Observations
Utilization of cloud-resolving models and multi-dimensional radiative transfer models to investigate the importance of 3D radiation effects on the numerical simulation of cloud fields and their properties.
Howard Barker; Jason Cole
An Intercomparison of Microphysical Retrieval Algorithms for Upper-Tropospheric Ice Clouds
The large horizontal extent, with its location in the cold upper troposphere, and ice composition make cirrus clouds important modulators of the Earth's radiation budget and climate. Cirrus cloud microphysical properties are difficult to measure ...
Jennifer M. Comstock; Sally A. McFarlane; Robert d'Entremont; Daniel DeSlover; David D. Turner; Gerald G. Mace; Sergey Y. Matrosov; Matthew D. Shupe; Patrick Minnis; David Mitchell; Kenneth Sassen; Zhien Wang
Global Circuit Model with Clouds
Cloud data from the International Satellite Cloud Climatology Project (ISCCP) database have been introduced into the global circuit model developed by Tinsley and Zhou. Using the cloud-top pressure data and cloud type information, the authors ...
Limin Zhou; Brian A. Tinsley
Cloud Computing Forum & Workshop II
Cloud Computing Forum & Workshop II. Purpose: On May 20, 2010, NIST hosted the first Cloud Computing Forum & Workshop. ...
Entrainment in Cumulus Clouds
Entrainment of dry air into cumulus clouds influences the development of the clouds in a major way. The many aspects of the entrainment process are examined in this paper by critically reviewing the literature from the time when investigations ...
Alan M. Blyth
Clouds in Tropical Cyclones
Clouds within the inner regions of tropical cyclones are unlike those anywhere else in the atmosphere. Convective clouds contributing to cyclogenesis have rotational and deep intense updrafts but tend to have relatively weak downdrafts. Within the ...
Robert A. Houze Jr.
North Australian Cloud Lines
A satellite classification and climatology of propagating mesoscale cloud fines in northern Australia is presented. These cloud fines range from long, narrow lines of shallow convection to extensive deep convective squall lines with mesoscale ...
W. Drosdowsky; G. J. Holland
Clouds within the inner regions of tropical cyclones are unlike those anywhere else in the atmosphere. Convective clouds contributing to cyclogenesis have rotational and deep intense updrafts but tend to have relatively weak downdrafts. Within ...
Automated cloud resource orchestration
Realizing Infrastructure-as-a-Service (IaaS) cloud requires a control platform for orchestrating the provisioning, configuration, management and decommissioning of a distributed set of diverse cloud resources (i.e., compute, storage, network) serving ...
Changbin Liu / Boon Thau Loo
ARM - Measurement - Cloud type
type ARM Data Discovery Browse Data Comments? We would love to hear from you Send us a note below or call us at 1-888-ARM-DATA. Send Measurement : Cloud type Cloud type such as...
Phenomenological Description of Tropical Clouds Using CloudSat Cloud Classification
Two years of tropical oceanic cloud observations are analyzed using the operational CloudSat cloud classification product and Cloud�Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) lidar. Relationships are examined between ...
Ali Behrangi; Terry Kubar; Bjorn Lambrigtsen
Cloud Computing at NERSC
Cloud Computing Energy Efficient Computing Exascale Computing Performance & Monitoring Tools Petascale Initiative Science Gateway Development Storage and IO Technologies Testbeds...
Time Correlations in Backscattering Radar Reflectivity Measurements from Cirrus Clouds
Time Correlations in Backscattering Radar Reflectivity Time Correlations in Backscattering Radar Reflectivity Measurements from Cirrus Clouds K. Ivanova, H. N. Shirer, and E. E. Clothiaux Pennsylvania State University University Park, Pennsylvania T. P. Ackerman Pacific Northwest National Laboratory Richland, Washington Introduction The state variables of the atmosphere exhibit correlations at various spatial and temporal scales. These correlations are crucial for understanding short- and long-term trends in climate. Cirrus clouds are important phenomena in the troposphere affecting climate. To improve future parameterization of cirrus clouds in climate models, we must understand the cloud properties and how they change within the cloud. We consider fluctuations of cloud radar signals obtained at isodepths within cirrus clouds
Surface based remote sensing of aerosol-cloud interactions
Surface based remote sensing of aerosol-cloud interactions Surface based remote sensing of aerosol-cloud interactions Feingold, Graham NOAA/Environmental Technology Laboratory Frisch, Shelby NOAA/Environmental Technology Laboratory Min, Qilong State University of New York at Albany Category: Cloud Properties We will present an analysis of the effect of aerosol on clouds at the Southern Great Plains ARM site. New methods for retrieving cloud droplet effective radius with radar (MMCR), multifilter rotating shadowband radiometer (MFRSR), and microwave radiometer (MWR) will be discussed. Relationships based on adiabatic clouds will be used to constrain retrievals. We will investigate the use of a range of proxies for cloud condensation nuclei, ranging from surface measurements of light scattering and accumulation mode number concentration, to lidar-measured extinction or
Rope Cloud over Land
Satellite imagery is used to document several rope clouds over the southeastern Unites States. Surface and upper-air data are examined for one of the rope clouds and possible reasons for the development and maintenance of this type cloud line are ...
Von S. Woods
User Centric Community Clouds
With the evolution in cloud technologies, users are becoming acquainted with seamless service provision. Nevertheless, clouds are not a user centric technology, and users become completely dependent on service providers. We propose a novel concept for ... Keywords: Cloud infrastructure, Identity management, User-centric systems
Jo�o Paulo Barraca; Alfredo Matos; Rui L. Aguiar
Simulations of cirrus clouds using an explicit cloud model: integrating ARM
Simulations of cirrus clouds using an explicit cloud model: integrating ARM Simulations of cirrus clouds using an explicit cloud model: integrating ARM water vapor and forcing data for analysis of cirrus formation and evolution Comstock, Jennifer Pacific Northwest National Laboratory Lin, Ruei-Fong NASA/Goddard Space Flight Center Starr, David NASA/Goddard Space Flight Center Yang, Ping Texas A&M Category: Modeling Understanding the atmospheric conditions required to initiate cirrus formation and produce observed microphysical properties is crucial to improving the representation of cirrus clouds in climate models. Ice formation in cirrus generally occurs at cold temperatures (below -30 C) and can take the form of either homogeneous or heterogeneous nucleation. The ice supersaturation required for ice formation is smaller for
ARM - Publications: Science Team Meeting Documents
Simulations of Mixed-Phase Altocumulus: An Evaluation of Remote Sensing Simulations of Mixed-Phase Altocumulus: An Evaluation of Remote Sensing Properties Versus Relative Ice/Water Content Sassen, K.(a) and Khvorostyanov, V.I.(b), University of Alaska Faibanks (a), Moscow Central Aerological Observatory (b) Mixed-phase clouds are acknowledged to be a harsh test of remote sensing data-based algorithms designed to derive microphysical and radiative properties. Yet, such clouds are globally ubiquitous. Using a 2-D cloud model with explicit microphysics and radiation, we evaluate the changes in mixed phase clouds caused by increasing ice content until glaciation occurs. The properties of the ice and water particle constituents are resolved independently, revealing the relative radiative contributions from the water phase source cloud versus the ice phase virga. Cloud contents are
Turbulent molecular clouds
Stars form within molecular clouds but our understanding of this fundamental process remains hampered by the complexity of the physics that drives their evolution. We review our observational and theoretical knowledge of molecular clouds trying to confront the two approaches wherever possible. After a broad presentation of the cold interstellar medium and molecular clouds, we emphasize the dynamical processes with special focus to turbulence and its impact on cloud evolution. We then review our knowledge of the velocity, density and magnetic fields. We end by openings towards new chemistry models and the links between molecular cloud structure and star--formation rates.
Hennebelle, Patrick
Testing a New Cirrus Cloud Parameterizaton
Testing a New Cirrus Cloud Parameterization Testing a New Cirrus Cloud Parameterization in NCAR CCM3 D. Zurovac-Jevtic, G. J. Zhang, and V. Ramanathan Center for Atmospheric Sciences Scripps Institute of Oceanography La Jolla, California Introduction Cirrus cloud cover and ice water content (IWC) are the two most important properties of cirrus clouds. However, in general circulation models (GCMs), their treatment is very crude. For example, in the National Center for Atmospheric Research (NCAR) Community Climate Model (CCM3), IWC is prescribed as a function of column-integrated water vapor and height (Hack 1998). The in situ observations in the tropics indicate that the cirrus IWC is an order of magnitude larger than what is prescribed in the model (McFarquhar and Heymsfield 1996). The comparison with the International
Research Highlight
Satellite Retrievals of Mixed-phase Cloud Properties Satellite Retrievals of Mixed-phase Cloud Properties Download a printable PDF Submitter: Ou, S., University of California, Los Angeles Area of Research: Cloud Distributions/Characterizations Working Group(s): Cloud Properties Journal Reference: Ou SS, KN Liou, XJ Wang, A Dybdahl, M Mussetto, LD Carey, J Niu, JA Kankiewicz, S Kidder, and TH Von der Haar. 2009. "Retrievals of mixed-phase cloud properties during the National Polar-Orbiting Operational Environmental Satellite System." Applied Optics, 48(8), 1452-1462. Images of mixed-phase retrieved (a) τi, (b) De, (c) τw, and (d) re for the Terra/MODIS scene of 14 October 2001 over North Platte, Nebraska. Also shown are (e) retrieved τi and τw versus MODIS τ within the pink box and (f) retrieved De and re versus MODIS re within the pink box.
Cloud displays for mobile users in a display cloud
The display cloud model allows users to select local and remote programmable displays, and add them to a user specific cloud display where the user can arrange them freely. On a cloud display, the abstraction representing remote graphical content is ... Keywords: cloud displays, display clouds, ubiquitous displays
Lars Tiede; John Markus Bj�rndalen; Otto J. Anshus
PowerPoint Presentation - No Slide Title
Arctic mixed-phase clouds: Arctic mixed-phase clouds: Sensitivity to ice initiation mechanisms Igor Sednev (firstname.lastname@example.com) and Surabi Menon (email@example.com) Lawrence Berkeley National Laboratory, Berkeley, CA 94720 Motivation The impacts of Arctic mixed-phase clouds on climate in terms of changes in surface radiative budgets remain uncertain due to the complexities in representation of mixed-phase clouds. The environmental conditions that determine Arctic cloud properties need to be thoroughly analyzed to fully represent these clouds in climate models. To evaluate the impact of ice initiation mechanisms on cloud glaciation time and develop a simplified bulk microphysics scheme for use in GCMs we use a modified version of the GISS SCM initialized with data from the DOE Arctic
Evaluation of Model-Predicted Top-of-Atmosphere Radiation and Cloud Parameters over Africa with Observations from GERB and SEVIRI
This study compared the Regional Atmospheric Climate Model version 2 (RACMO) with satellite data by simultaneously looking at cloud properties and top-of-atmosphere (TOA) fluxes. This study used cloud properties retrieved from Spinning Enhanced ...
Wouter Greuell; Erik van Meijgaard; Nicolas Clerbaux; Jan Fokke Meirink
BNL | Cloud Lifecycle Infrastructure
Cloud Life Cycle Infrastructure Cloud Life Cycle Infrastructure An important component of any long-term atmospheric measurement program is the quality control and maintenance of the datastreams from instrument systems. Further, the raw measurements from atmospheric remote sensing instrumentation are not directly useable by the majority of the scientific community. These raw measurements must be interpreted and converted to geophysical quantities that can be more readily used by a greater number of scientists to address important questions regarding the Earth's climate system. The cloud life cycle infrastructure group at BNL is led by Dr. Michael Jensen and is responsible for the development and production of cloud-related value-added products (VAPs). The cloud life cycle infrastructure group also provides mentorships for the millimeter cloud
Reconciling Simulated and Observed Views of Clouds: MODIS, ISCCP, and the Limits of Instrument Simulators
The properties of clouds that may be observed by satellite instruments, such as optical thickness and cloud-top pressure, are only loosely related to the way clouds are represented in models of the atmosphere. One way to bridge this gap is through ...
Robert Pincus; Steven Platnick; Steven A. Ackerman; Richard S. Hemler; Robert J. Patrick Hofmann
Indian Summer Monsoon Drought 2009: Role of Aerosol and Cloud Microphysics
Cloud dynamics played a fundamental role in defining Indian summer monsoon (ISM) rainfall during drought in 2009. The anomalously negative precipitation was consistent with cloud properties. Although, aerosols inhibited the growth of cloud effective radius in the background of sparse water vapor, their role is secondary. The primary role, however, is played by the interactive feedback between cloud microphysics and dynamics owing to reduced efficient cloud droplet growth, lesser latent heating release and shortage of water content. Cloud microphysical processes were instrumental for the occurrence of ISM drought 2009.
Hazra, Anupam; Taraphdar, Sourav; Halder, Madhuparna; Pokhrel, S.; Chaudhari, H. S.; Salunke, K.; Mukhopadhyay, P.; Rao, S. A.
Posters Sensitivity of Cirrus Cloud Radiative
7 7 Posters Sensitivity of Cirrus Cloud Radiative Properties to Ice Crystal Size and Shape in General Circulation Model Simulations D. L. Mitchell Desert Research Institute Reno, Nevada J. E. Kristjánsson Department of Geophysics University of Oslo, Norway M. J. Newman Los Alamos National Laboratory Los Alamos, New Mexico Introduction Recent research (e.g., Mitchell and Arnott 1994) has shown that the radiative properties of cirrus clouds (i.e., optical depth, albedo, emissivity) depend on the shapes and sizes of ice crystals. For instance, the cloud albedo may vary by a factor of two, depending on whether hexagonal columns or bullet rosette ice crystals are assumed for a given ice water path (IWP). This variance occurs primarily because, at sizes characteristic of cirrus
Observations of chemical differentiation in clumpy molecular clouds
We have extensively mapped a sample of dense molecular clouds (L1512, TMC-1C, L1262, Per 7, L1389, L1251E) in lines of HC3N, CH3OH, SO and C^{18}O. We demonstrate that a high degree of chemical differentiation is present in all of the observed clouds. We analyse the molecular maps for each cloud, demonstrating a systematic chemical differentiation across the sample, which we relate to the evolutionary state of the cloud. We relate our observations to the cloud physical, kinematical and evolutionary properties, and also compare them to the predictions of simple chemical models. The implications of this work for understanding the origin of the clumpy structures and chemical differentiation observed in dense clouds are discussed.
J. V. Buckle; S. D. Rodgers; E. S. Wirstr�m; S. B. Charnley; A. J. Markwick-Kemper; H. M. Butner; S. Takakuwa
BNL | Cloud Lifecycle Research
to be one of the major sources of uncertainty in numerical simulations of climate and weather. Improvement of the representation of clouds in numerical models requires fundamental...
Supersaturation Fluctuations in Cirrus Clouds Driven by Colored Noise
Fundamental properties of ice supersaturation variability in cirrus clouds are studied by means of an idealized probabilistic model. Damped supersaturation fluctuations are assumed to be exponentially correlated in time, statistically stationary, ...
B. K�rcher
The characterization of particle clouds using optical imaging techniques
Optical imaging techniques can be used to provide a better understanding of the physical properties of particle clouds. The purpose of this thesis is to design, perform and evaluate a set of experiments using optical imaging ...
Bruce, Elizabeth J. (Elizabeth Jane), 1972-
On the Transition of Contrails into Cirrus Clouds
In situ observations of the microphysical properties of upper-tropospheric contrails and cirrus clouds have been performed during more than 15 airborne missions over central Europe. Experimental and technical aspects concerning in situ ...
F. Schr�der; B. K�rcher; C. Duroure; J. Str�m; A. Petzold; J.-F. Gayet; B. Strauss; P. Wendling; S. Borrmann
Modeling Entrainment and Finescale Mixing in Cumulus Clouds
A model used to study entrainment and mixing of thermodynamic properties in the stratus-topped boundary layer has been extended to represent these processes in cumulus clouds. The new model, called the �explicit mixing parcel model� (EMPM), ...
Steven K. Krueger; Chwen-Wei Su; Patrick A. McMurtry
Assessment Part 2: Cirrus Radiative Flux Study Using RadarLidarAERI Derived Cloud Properties David Tobin, Lori Borg, David Turner, Robert Holz, Daniel DeSlover, Hank Revercomb,...
Cloud Classification Before Luke Howard
A brief outline of the history of cloud painting prior to the first cloud classification schemes of Luke Howard and Lamarck is presented. It is shown that European painters had accurately represented most of the different cloud forms between ...
Stanely David Gedzelman
Radar Reflectivity of Cumulus Clouds
The relationships between the radar reflectivity factor Z and significant physical cloud parameters are studied from a dataset collected with an instrumented aircraft in non- or very weakly precipitating warm clouds. The cloud droplet populations ...
Henri Sauvageot; Jilani Omar
Using Cloud-Resolving Model Simulations of Deep Convection to Inform Cloud Parmaterizations in Large-Scale Models
Using Cloud-Resolving Model Simulations Using Cloud-Resolving Model Simulations of Deep Convection to Inform Cloud Parameterizations in Large-Scale Models S. A. Klein National Oceanic and Atmospheric Administration Geophysical Fluid Dynamics Laboratory Princeton, New Jersey R. Pincus National Oceanic and Atmospheric Administration Cooperative Institute for Research in Environmental Science Climate Diagnostics Center Boulder, Colorado K. -M. Xu National Aeronautics and Space Administration Langley Research Center Hampton, Virginia Abstract Cloud parameterizations in large-scale models struggle to address the significant non-linear effects of radiation and precipitation that arise from horizontal inhomogeneity in cloud properties at scales smaller than the grid box size of the large-scale models. Statistical cloud schemes provide an attractive
An Assessment of the Parameterization of Subgrid-Scale Cloud Effects on Radiative Transfer. Part II: Horizontal Inhomogeneity
The role of horizontal inhomogeneity in radiative transfer through cloud fields is investigated within the context of the two-stream approximation. Spatial correlations between cloud optical properties and the radiance field are introduced in the ...
Norman B. Wood; Philip M. Gabriel; Graeme L. Stephens
The 27�28 October 1986 FIRE IFO Cirrus Case Study: A Five Lidar Overview of Cloud Structure and Evolution
Optical remote sensing measurements of cirrus cloud properties were collected by one airborne and four ground-based lidar systems over a 32-h period during this cue study from the First ISCCP (International Satellite Cloud Climatology Program) ...
Kenneth Sassen; Christian J. Grund; James D. Spinhirne; Michael M. Hardesty; Jose M. Alvarez
Cirrus Clouds and the Large-Scale Atmospheric State: Relationships Revealed by Six Years of Ground-Based Data
The properties of cirrus clouds observed at the Atmospheric Radiation Measurement (ARM) Climate Research Facility (ACRF) in Oklahoma are documented from a nearly continuous 6-yr record of 35-GHz cloud radar data. Cirrus frequency over the ACRF is ...
Gerald G. Mace; Sally Benson; Erik Vernon
Marine Stratocumulus Cloud Fields off the Coast of Southern California Observed Using LANDSAT Imagery. Part II: Textural Analysis
Statistical measures of the spatial distributions of gray levels (cloud reflectivities) are determined for LANDSAT Multispectral Scanner digital data. Textural properties for twelve stratocumulus cloud fields, seven cumulus fields, and two cirrus ...
R. M. Welch; S. K. Sengupta; K. S. Kuo
Molecular Line Absorption in a Scattering Atmosphere. Part III: Pathlength Characteristics and Effects of Spatially Heterogeneous Clouds
The paper analyzes the influence of horizontal variability of clouds on sunlight reflected in a narrow portion of the solar spectrum and how this influence affects the ability to estimate cloud properties from measurements of reflection. This ...
Andrew K. Heidinger; Graeme L. Stephens
ARM - PI Product - Atmospheric State, Cloud Microphysics & Radiative Flux
ProductsAtmospheric State, Cloud Microphysics & ProductsAtmospheric State, Cloud Microphysics & Radiative Flux Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send PI Product : Atmospheric State, Cloud Microphysics & Radiative Flux 1997.01.01 - 2010.12.31 Site(s) NSA SGP TWP General Description This data product contains atmospheric thermodynamics, cloud properties, radiative fluxes and radiative heating rates. The data represent a characterization of the physical state of the atmospheric column compiled on a five-minute temporal and 90m vertical grid. Sources for this information include raw measurements, cloud property and radiative retrievals, retrievals and derived variables from other third-party sources, and radiative calculations using the derived quantities.
Overview of Arctic Cloud and Radiation Characteristics
To provide a background for ARM's activities at the North Slope of Alaska/Adjacent Arctic Ocean sites, an overview is given of our current state of knowledge of Arctic cloud and radiation properties and processes. The authors describe the Arctic ...
Judith A. Curry; Julie L. Schramm; William B. Rossow; David Randall
Molecular cloud regulated star formation in galaxies
We describe a numerical implementation of star formation in disk galaxies, in which the conversion of cooling gas to stars in the multiphase interstellar medium is governed by the rate at which molecular clouds are formed and destroyed. In the model, clouds form from thermally unstable ambient gas and get destroyed by feedback from massive stars and thermal conduction. Feedback in the ambient phase cycles gas into a hot galactic fountain or wind. We model the ambient gas hydrodynamically using smoothed particle hydrodynamics (SPH). However, we cannot resolve the Jeans mass in the cold and dense molecular gas and, therefore, represent the cloud phase with ballistic particles that coagulate when colliding. We show that this naturally produces a multiphase medium with cold clouds, a warm disk, hot supernova bubbles and a hot, tenuous halo. Our implementation of this model is based on the Gadget N-Body code. We illustrate the model by evolving an isolated Milky Way-like galaxy and study the properties of a disk formed in a rotating spherical collapse. Many observed properties of disk galaxies are reproduced well, including the molecular cloud mass spectrum, the molecular fraction as a function of radius, the Schmidt law, the stellar density profile and the appearance of a galactic fountain.
C. M. Booth; T. Theuns; T. Okamoto
Using ARM data to correct plane-parallel satellite retrievals of cloud
Using ARM data to correct plane-parallel satellite retrievals of cloud Using ARM data to correct plane-parallel satellite retrievals of cloud properties Dong, Xiquan University of North Dakota Minnis, Patrick NASA Langley Research Center Xi, Baike University of North Dakota Khaiyer, Mandana Analytical Services and Material, Inc. Category: Cloud Properties The angular variations of cloud properties derived from GOES data are examined using simultaneously collocated ARM surface observations/retrievals at the DOE ARM SGP site during the 6-yr period from January 1997 to December 2002. The dependencies of GOES cloud retrievals on solar zenith angle (SZA), scattering angle (SCA), and relative azimuth angle (RZA) are investigated for single-layer and overcast low-level stratus clouds. The GOES-retrieved cloud-droplet effective radius (re),
Cloud Computing Forum & Workshop IV
Cloud Computing Forum & Workshop IV. ... NIST announces the Cloud Computing Forum & Workshop IV to be held on November 2, 3 and 4, 2011. ...
A new approach for simultaneously retrieving cloud albedo and cloud fraction from surface-based shortwave radiation measurements
ENVIRONMENTAL ENVIRONMENTAL RESEARCH LETTERS Environ. Res. Lett. 8 (2013) 044023 (9pp) doi:10.1088/1748-9326/8/4/044023 A new approach for simultaneously retrieving cloud albedo and cloud fraction from surface-based shortwave radiation measurements Yu Xie and Yangang Liu Environmental Sciences Department, Brookhaven National Laboratory, Upton, NY 11973, USA E-mail: email@example.com Received 27 June 2013 Accepted for publication 8 October 2013 Published 30 October 2013 Online at stacks.iop.org/ERL/8/044023 Abstract Surface-based measurements of shortwave (SW) radiative fluxes contain valuable information on cloud properties, but have not been fully used to infer those properties. Here a new analytical approach is presented that simultaneously infers cloud albedo and cloud fraction from surface-based measurements of total and direct radiative fluxes. An inspection of the
Toward Understanding of Differences in Current Cloud Retrievals of ARM Ground-based Measurements
Accurate observations of cloud microphysical properties are needed for evaluating and improving the representation of cloud processes in climate models. However, large differences are found in current cloud products retrieved from ground-based remote sensing measurements using various retrieval algorithms. Understanding the differences is an important step to address uncertainties in the cloud retrievals. In this study, an in-depth analysis of nine existing ground-based cloud retrievals using ARM remote sensing measurements is carried out. We place emphasize on boundary layer overcast clouds and high level ice clouds, which are the focus of many current retrieval development efforts due to their radiative importance and relatively simple structure. Large systematic discrepancies in cloud microphysical properties are found in these two types of clouds among the nine cloud retrieval products, particularly for the cloud liquid and ice effective radius. It is shown that most of these large differences have their roots in the retrieval algorithms used by these cloud products, including the retrieval theoretical bases, assumptions, as well as input and constraint parameters. This study suggests the need to further validate current retrieval theories and assumptions and even the development of new retrieval algorithms with more observations under different cloud regimes.
Zhao, Chuanfeng; Xie, Shaocheng; Klein, Stephen A.; Protat, Alain; Shupe, Matthew D.; McFarlane, Sally A.; Comstock, Jennifer M.; Delanoe, Julien; Deng, Min; Dunn, Maureen; Hogan, Robin; Huang, Dong; Jensen, Michael; Mace, Gerald G.; McCoy, Renata; O'Conner, Ewan J.; Turner, Dave; Wang, Zhien
Cryptographic cloud storage
We consider the problem of building a secure cloud storage service on top of a public cloud infrastructure where the service provider is not completely trusted by the customer. We describe, at a high level, several architectures that combine recent and ...
Seny Kamara; Kristin Lauter
CONTRIBUTED Green Cloud Computing
widely dis- cussed, the shift in energy usage in a cloud computing model has received little attention cloud computing services typically operate. We consider energy consumption models of the transport of energy per bit also allows the results to be easily scaled to any usage level. We consider both public
Tucker, Rod
Table 3 Lubricant properties...45.0 6.80 103 0.67 �?� �?� 5W-30 motor oil, SG/CD, energy conserving II, ILSAC,
McFarquhar, G. Zhang, M.R. Poellot, P.J. DeMott, A.J. Prenni and A.J. Heymsfield, 2007: Ice properties of single-layer stratocumulus during the Mixed-Phase Arctic Cloud...
Characterizing Mixed-Phase Clouds from the Ground: a Status Report Characterizing Mixed-Phase Clouds from the Ground: a Status Report Download a printable PDF Submitter: Shupe, M., University of Colorado Area of Research: Cloud Distributions/Characterizations Working Group(s): Cloud Properties Journal Reference: Shupe, MD, JS Daniel, G De Boer, EW Eloranta, P Kollias, E Luke, CN Long, DD Turner, and J Verlinde. 2008. "A focus on mixed-phase clouds: The status of ground-based observational methods." Bulletin of the American Meteorological Society, accepted for publication in October 2008 issue. Figure 1. Retrieved cloud properties for 9 October 2004 at Barrow: (a) Multisensor cloud phase classification, (b) radar Doppler spectra cloud phase classification, (c) ice water content, (d) ice particle effective radius, (e) adiabatic liquid water content scaled to the microwave
Mixed-Phase Clouds: Simulation of Optical Mixed-Phase Clouds: Simulation of Optical and Radiative Properties T. B. Zhuravleva Institute of Atmospheric Optics Tomsk, Russia A. G. Petrushin Institute of Experimental Meteorology Obninsk, Russia Introduction Generally, the radiative properties of ice-crystal and mixed-phase clouds are studied using a plane- parallel, horizontally homogeneous cloud model. However, this model neglects horizontal inhomogeneity, a characteristic of the real clouds arising due to stochastic cloud geometry. In many cases, this neglect leads to unsatisfactory treatment of solar radiative transfer in the cloudy atmosphere. The present work is aimed at studying the combined effects of the random cloud geometry and cloud phase composition on the albedo R, diffuse transmittance Q
Cloud Computing Forensic Science Workshop
Cloud Computing Forensic Science Workshop. Purpose: The New Frontiers in IT and Measurement Science Rapid advances ...
A marketplace for cloud resources
Cloud computing is an emerging paradigm aimed to offer users pay-per-use computing resources, while leaving the burden of managing the computing infrastructure to the cloud provider. We present a new programming and pricing model that gives the cloud ... Keywords: cloud computing, iaas, large-scale scheduling, pricing models, worst-case execution time
Thomas A. Henzinger; Anmol V. Singh; Vasu Singh; Thomas Wies; Damien Zufferey
Energy.gov (U.S. Department of Energy (DOE)) Indexed Site
7 7 AUDIT REPORT PERSONAL PROPERTY AT THE OAK RIDGE OPERATIONS OFFICE AND THE OFFICE OF SCIENTIFIC AND TECHNICAL INFORMATION U.S. DEPARTMENT OF ENERGY OFFICE OF INSPECTOR GENERAL OFFICE OF AUDIT SERVICES APRIL 1998 Page 10 DEPARTMENT OF ENERGY Washington, DC 20585 April 6, 1998 MEMORANDUM FOR THE MANAGER, OAK RIDGE OPERATIONS OFFICE AND THE DIRECTOR, OFFICE OF SCIENTIFIC AND TECHNICAL INFORMATION FROM: Terry L. Brendlinger Eastern Regional Audit Office Office of Inspector General SUBJECT: INFORMATION: Audit Report on "Personal Property at the Oak Ridge Operations Office and the Office of Scientific and Technical Information" BACKGROUND The Oak Ridge Operations Office (Operations Office) and the Office of Scientific and Technical Information
ARM - Field Campaign - MASRAD: Cloud Study from the 2NFOV at Pt. Reyes
govCampaignsMASRAD: Cloud Study from the 2NFOV at Pt. Reyes Field govCampaignsMASRAD: Cloud Study from the 2NFOV at Pt. Reyes Field Campaign Campaign Links AMF Point Reyes Website Related Campaigns MArine Stratus Radiation Aerosol and Drizzle (MASRAD) IOP 2005.03.14, Miller, AMF Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Campaign : MASRAD: Cloud Study from the 2NFOV at Pt. Reyes Field Campaign 2005.06.02 - 2005.09.30 Lead Scientist : Warren Wiscombe For data sets, see below. Description Cloud optical depth is one of the most important cloud optical properties, and vital for any cloud-radiation parameterization. Our ARM Science Team project has pioneered an algorithm to retrieve cloud optical depth in a fully three-dimensional cloud situation using zenith radiances from the ARM
A new model of cloud drop distribution that simulates the observed drop
A new model of cloud drop distribution that simulates the observed drop A new model of cloud drop distribution that simulates the observed drop clustering: effect of clustering on extinction coefficient estimates Knyazikhin, Yuri Boston University Marshak, Alexander NASA Goddard Space Flight Center Larsen, Michael Michigan Technological University Wiscombe, Warren BNL/NASA Goddard Space Flight Center Category: Modeling Cloud droplet size distribution is one of the most fundamental subjects in cloud physics. Understanding of spatial distribution and small-scale fluctuations of cloud droplets is essential for both cloud physics and atmospheric radiation. For cloud physics, it relates to the coalescence growth of raindrops while for radiation, it has a strong impact on a cloud's radiative properties. We have developed new size dependent models
The cloud condensation nuclei and ice nuclei effects on tropical anvil characteristics and water vapor of the tropical tropopause layer
Cloud anvils from deep convective clouds are of great importance to the radiative energy budget and the aerosol impact on them is the least understood. Few studies examined the effects of both cloud condensation nuclei (CCN) and ice nuclei (IN) on anvil properties and water vapor content (WVC) in the Tropical Tropopause Layer (TTL). Using a 3-dimensional cloud-resolving model with size-resolved cloud microphysics, we focus on the CCN and IN effects on cloud anvil properties and WVC in the TTL. We find that cloud microphysical changes induced by CCN/IN play a very important role in determining cloud anvil area and WVC in the TTL, whether convection is enhanced or suppressed. Also, CCN effects on anvil microphysical properties, anvil size and lifetime are much more evident relative to IN. IN has little effect on convection, but can increase ice number and mass concentrations significantly under humid conditions. CCN in the PBL is found to have greater effects on convective strength and mid-tropospheric CCN has negligible effects on convection and cloud properties. Convective transport may only moisten the main convective outflow region but the cloud anvil size determines the WVC in the TTL domain. This study shows an important role of CCN in the lower-troposphere in modifying convection, the upper-level cloud properties. It also shows the effects of IN and the PBL CCN on the upper-level clouds depends on the humidity, resolving some contradictory results in past studies. 2
Fan, Jiwen; Comstock, Jennifer M.; Ovchinnikov, Mikhail
Toward understanding of differences in current cloud retrievals of ARM ground-based measurements
Accurate observations of cloud microphysical properties are needed for evaluating and improving the representation of cloud processes in climate models and better estimate of the Earth radiative budget. However, large differences are found in current cloud products retrieved from ground-based remote sensing measurements using various retrieval algorithms. Understanding the differences is an important step to address uncertainties in the cloud retrievals. In this study, an in-depth analysis of nine existing ground-based cloud retrievals using ARM remote sensing measurements is carried out. We place emphasis on boundary layer overcast clouds and high level ice clouds, which are the focus of many current retrieval development efforts due to their radiative importance and relatively simple structure. Large systematic discrepancies in cloud microphysical properties are found in these two types of clouds among the nine cloud retrieval products, particularly for the cloud liquid and ice particle effective radius. Note that the differences among some retrieval products are even larger than the prescribed uncertainties reported by the retrieval algorithm developers. It is shown that most of these large differences have their roots in the retrieval theoretical bases, assumptions, as well as input and constraint parameters. This study suggests the need to further validate current retrieval theories and assumptions and even the development of new retrieval algorithms with more observations under different cloud regimes.
Zhao C.; Dunn M.; Xie, S.; Klein, S. A.; Protat, A.; Shupe, M. D.; McFarlane, S. A.; Comstock, J. M.; Delano�, J.; Deng, M.; Hogan, R. J.; Huang, D.; Jensen, M. P.; Mace, G. G.; McCoy, R.; O�Connor, E. J.; Turner, D. D.; Wang, Z.
3. New Cloud Climatology
New Cloud Climatology New Cloud Climatology Computed for the summers (May-Au- gust) 2000 through 2004 (Berg and Kassianov 2008). Uses ARSCL VAP, Total Sky Imager, and radar wind profiler. * * Initial Evaluation of the Cumulus Potential Scheme at the ACRF SGP Site Larry Berg, William Gustafson, and Evgueni Kassianov Pacific Northwest National Laboratory 1. Motivation Shallow clouds are poorly predicted by current global and regional scale models. A new parameterization has been devel- oped that links the boundary-layer turbu- lence and the shallow clouds. 2. The CuP Parameterization The Cumulus Potential (CuP) param- eterization uses Probability Density Functions (PDFs) of temperature and moisture to represent the subgrid scale
CDIAC Cloud Data Sets
Period of Record A Gridded Climatology of Clouds over Land (1971-1996) and Ocean (1954-2008) from Surface Observations Worldwide (CDIAC NDP-026E) C.J. Hahn and S.G. Warren...
ISCCP Cloud Data Products
The operational data collection phase of the International Satellite Cloud Climatology Project (ISCCP) began in July 1983. Since then, visible and infrared images from an international network of weather satellites have been routinely processed ...
William B. Rossow; Robert A. Schiffer
Cloud Transmissivities for Canada
Transmissivities are determined for different cloud types using nine years of hourly irradiance measurements under overcast skies at six Canadian stations. Values for individual stations and for pooled data using irradiances uncorrected for ...
J. A. Davies; M. Abdel-Wahab; J. E. Howard
Marine Cloud Brightening
The idea behind the marine cloud-brightening (MCB) geoengineering technique is that seeding marine stratocumulus clouds with copious quantities of roughly monodisperse sub-micrometre sea water particles might significantly enhance the cloud droplet number concentration, and thereby the cloud albedo and possibly longevity. This would produce a cooling, which general circulation model (GCM) computations suggest could - subject to satisfactory resolution of technical and scientific problems identified herein - have the capacity to balance global warming up to the carbon dioxide-doubling point. We describe herein an account of our recent research on a number of critical issues associated with MCB. This involves (i) GCM studies, which are our primary tools for evaluating globally the effectiveness of MCB, and assessing its climate impacts on rainfall amounts and distribution, and also polar sea-ice cover and thickness; (ii) high-resolution modelling of the effects of seeding on marine stratocumulus, which are required to understand the complex array of interacting processes involved in cloud brightening; (iii) microphysical modelling sensitivity studies, examining the influence of seeding amount, seedparticle salt-mass, air-mass characteristics, updraught speed and other parameters on cloud-albedo change; (iv) sea water spray-production techniques; (v) computational fluid dynamics studies of possible large-scale periodicities in Flettner rotors; and (vi) the planning of a three-stage limited-area field research experiment, with the primary objectives of technology testing and determining to what extent, if any, cloud albedo might be enhanced by seeding marine stratocumulus clouds on a spatial scale of around 100 km. We stress that there would be no justification for deployment of MCB unless it was clearly established that no significant adverse consequences would result. There would also need to be an international agreement firmly in favour of such action.
Latham, John; Bower, Keith; Choularton, Tom; Coe, H.; Connolly, P.; Cooper, Gary; Craft, Tim; Foster, Jack; Gadian, Alan; Galbraith, Lee; Iacovides, Hector; Johnston, David; Launder, Brian; Leslie, Brian; Meyer, John; Neukermans, Armand; Ormond, Bob; Parkes, Ben; Rasch, Philip J.; Rush, John; Salter, Stephen; Stevenson, Tom; Wang, Hailong; Wang, Qin; Wood, Robert
Posters A Stratiform Cloud Parameterization for General Circulation Models
Posters A Stratiform Cloud Parameterization for General Circulation Models S. J. Ghan and L. R. Leung Pacific Northwest Laboratory Richland, Washington C. C. Chuang and J. E. Penner Lawrence Livermore National Laboratory Livermore, California J. McCaa University of Washington Seattle, Washington The crude treatment of clouds in general circulation models (GCMs) is widely recognized as a major limitation in applying these models to predictions of global climate change. The purpose of this project is to develop a parameterization for stratiform clouds in GCMs that expresses stratiform clouds in terms of bulk microphysical properties and their subgrid variability. In this parameterization, precipitating cloud species are distinguished from non-precipitating species, and the liquid
[Treatment of cloud radiative effects in general circulation models
This is a renewal proposal for an on-going project of the Department of Energy (DOE)/Atmospheric Radiation Measurement (ARM) Program. The objective of the ARM Program is to improve the treatment of radiation-cloud in GCMs so that reliable predictions of the timing and magnitude of greenhouse gas-induced global warming and regional responses can be made. The ARM Program supports two research areas: (I) The modeling and analysis of data related to the parameterization of clouds and radiation in general circulation models (GCMs); and (II) the development of advanced instrumentation for both mapping the three-dimensional structure of the atmosphere and high accuracy/precision radiometric observations. The present project conducts research in area (I) and focuses on GCM treatment of cloud life cycle, optical properties, and vertical overlapping. The project has two tasks: (1) Development and Refinement of GCM Radiation-Cloud Treatment Using ARM Data; and (2) Validation of GCM Radiation-Cloud Treatment.
Wang, W.C.
Recent observations of molecular clouds around rich massive star clusters including NGC 3603, Westerlund 2, and M20 revealed that the formation of massive stars could be triggered by a cloud-cloud collision. By using three-dimensional, isothermal, magnetohydrodynamics simulations with the effect of self-gravity, we demonstrate that massive, gravitationally unstable, molecular cloud cores are formed behind the strong shock waves induced by cloud-cloud collision. We find that the massive molecular cloud cores have large effective Jeans mass owing to the enhancement of the magnetic field strength by shock compression and turbulence in the compressed layer. Our results predict that massive molecular cloud cores formed by the cloud-cloud collision are filamentary and threaded by magnetic fields perpendicular to the filament.
Inoue, Tsuyoshi [Department of Physics and Mathematics, Aoyama Gakuin University, Sagamihara, Kanagawa 252-5258 (Japan); Fukui, Yasuo, E-mail: firstname.lastname@example.com [Department of Physics, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602 (Japan)
Cloud and Radiative Characteristics of Tropical Deep Convective Systems in Extended Cloud Objects from CERES Observations
The physical and radiative properties of tropical deep convective systems for the period from January to August 1998 are examined with the use of Clouds and the Earth�s Radiant Energy System Single-Scanner Footprint (SSF) data from the Tropical ...
Evaluate the Effect of Upper-Level Cirrus Clouds on Satellite Retrievals of Low-Level Cloud Droplet Effective Radius
the Effect of Upper-Level Cirrus Clouds the Effect of Upper-Level Cirrus Clouds on Satellite Retrievals of Low-Level Cloud Droplet Effective Radius F.-L. Chang and Z. Li Earth System Science Interdisciplinary Center University of Maryland College Park, Maryland Z. Li Department of Meteorology University of Maryland College Park, Maryland Introduction The earth's radiation budget is sensitive to changes in the microphysical properties of low-level stratiform clouds. Their extensive coverage can significantly reduce the solar energy absorbed by the earth system. An estimate of reducing the global-mean droplet effective radius (r e ) of these low-level clouds by ~2 µm, while keeping the column liquid water constant would balance the warming due to CO 2 doubling in the atmosphere (Slingo 1990). Accurate determination of the droplet r
How Aerosols Affect Cloud Properties in Arctic Mixed-Phase Stratocumulus How Aerosols Affect Cloud Properties in Arctic Mixed-Phase Stratocumulus Download a printable PDF Submitter: McFarquhar, G., University of Illinois, Urbana Area of Research: Cloud-Aerosol-Precipitation Interactions Working Group(s): Cloud-Aerosol-Precipitation Interactions Journal Reference: Jackson RC, GM McFarquhar, AV Korolev, ME Earle, PS Liu, RP Lawson, S Brooks, M Wolde, A Laskin, and M Freer. 2012. "The dependence of ice microphysics on aerosol concentration in arctic mixed-phase stratus clouds during ISDAC and M-PACE." Journal of Geophysical Research - Atmospheres, 117, D15207, doi:10.1029/2012JD017668. Cloud mean ice crystal concentration Nice(D ≥ 50 micrometers) versus mean aerosol concentration (NPCASP) above cloud for all 41 vertical profiles
ARM - Evaluation Product - CMWG Data - SCM-Forcing Data, Cloud
ProductsCMWG Data - SCM-Forcing Data, Cloud ProductsCMWG Data - SCM-Forcing Data, Cloud Microphysical Properties and Radiative Heating Profiles Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Evaluation Product : CMWG Data - SCM-Forcing Data, Cloud Microphysical Properties and Radiative Heating Profiles Site(s) GAN HFE NSA SGP TWP General Description SCM-forcing data are derived from the ARM Program observational data using the constrained variational analysis approach (Zhang and Lin 1997 and Zhang et al. 2001). The resulting products include both the large-scale forcing terms and the evaluation fields, which can be used for driving the Single-Column Models (SCMs) and Cloud Resolving Models (CRMs) and validating model simulations. Results from our studies are then used to
Aerosols and clouds in chemical transport models and climate models.
Clouds exert major influences on both shortwave and longwave radiation as well as on the hydrological cycle. Accurate representation of clouds in climate models is a major unsolved problem because of high sensitivity of radiation and hydrology to cloud properties and processes, incomplete understanding of these processes, and the wide range of length scales over which these processes occur. Small changes in the amount, altitude, physical thickness, and/or microphysical properties of clouds due to human influences can exert changes in Earth's radiation budget that are comparable to the radiative forcing by anthropogenic greenhouse gases, thus either partly offsetting or enhancing the warming due to these gases. Because clouds form on aerosol particles, changes in the amount and/or composition of aerosols affect clouds in a variety of ways. The forcing of the radiation balance due to aerosol-cloud interactions (indirect aerosol effect) has large uncertainties because a variety of important processes are not well understood precluding their accurate representation in models.
Lohmann,U.; Schwartz, S. E.
Is the Sun Embedded in a Typical Interstellar Cloud?
The physical properties and kinematics of the partially ionized interstellar material near the Sun are typical of warm diffuse clouds in the solar vicinity. The interstellar magnetic field at the heliosphere and the kinematics of nearby clouds are naturally explained in terms of the S1 superbubble shell. The interstellar radiation field at the Sun appears to be harder than the field ionizing ambient diffuse gas, which may be a consequence of the low opacity of the tiny cloud surrounding the heliosphere. The spatial context of the Local Bubble is consistent with our location in the Orion spur.
P. C. Frisch
Total aerosol effect: forcing or radiative flux perturbation?
heterogeneous ice nucleation in mixed-phase clouds, Environ.interactions with mixed-phase and ice clouds can be comparedice nuclei for the indirect aerosol effect on stratiform mixed-phase
Lohmann, Ulrike
Cirrus Clouds. Part I: A Cirrus Cloud Model
A two-dimensional (x, z), time-dependent, numerical cloud model is developed for the purpose of investigating the role of various physical processes involved in the maintenance of cirriform clouds. In addition to accounting for dynamic and ...
David O'C. Starr; Stephen K. Cox
On the Use of Cloud Forcing to Estimate Cloud Feedback
Uncertainty in cloud feedback is the leading cause of discrepancy in model predictions of climate change. The use of observed or model-simulated radiative fluxes to diagnose the effect of clouds on climate sensitivity requires an accurate ...
Brian J. Soden; Anthony J. Broccoli; Richard S. Hemler
Liquid and Ice Cloud Microphysics in the CSU General Circulation Model. Part II: Impact on Cloudiness, the Earth's Radiation Budget, and the General Circulation of the Atmosphere
A prognostic equation for the mass of condensate associated with large-scale cloudiness introduces a direct coupling between the atmospheric moisture budget and the radiation budget through interactive cloud amounts and cloud optical properties. ...
Laura D. Fowler; David A. Randall
The Vertical Structure of Cloud Occurrence and Radiative Forcing at the SGP ARM Site as Revealed by 8 Years of Continuous Data
Data collected at the Atmospheric Radiation Measurement (ARM) Program ground sites allow for the description of the atmospheric thermodynamic state, cloud occurrence, and cloud properties. This information allows for the derivation of estimates ...
Gerald G. Mace; Sally Benson
Comparisons of CCN with Supercooled Clouds
More than 140 supercooled clouds were compared with corresponding out-of-cloud cloud condensation nuclei (CCN) measurements. In spite of significant differences in altitude, temperature, distances from cloud base, updraft velocity (W), ...
James G. Hudson; Stephen Noble; Vandana Jha
Effects of CCN Concentrations on Stratus Clouds
Comparisons between cloud-base CCN concentrations and cloud droplet concentrations in stratus clouds over San Diego and 100 km out to sea showed a positive correlation. The supersaturation in these clouds, as derived from the matching of the CCN ...
More Observations of Small Funnel Clouds and Other Tubular Clouds
In this brief contribution, photographic documentation is provided of a variety of small, tubular-shaped clouds and of a small funnel cloud pendant from a convective cloud that appears to have been modified by flow over high-altitude mountains in ...
Howard B. Bluestein
ETSI CLOUD - initial standardization requirements for cloud services
While the technological basis for cloud services is relatively mature, the development of the market is still at an early stage. There is considerable potential, but also a number of widely held concerns which are inhibiting mainstream adoption of cloud ... Keywords: ETSI, cloud services, standardization
Karsten Oberle; Mike Fisher
The Magellan Final Report on Cloud Computing
resources. 1. Finding Tropical Cyclones on a Cloud Computing2010 2. Finding Tropical Cyclones on Clouds, D. Hasenkamp
Coghlan, Susan
Ash cloud aviation advisories
During the recent (12--22 June 1991) Mount Pinatubo volcano eruptions, the US Air Force Global Weather Central (AFGWC) requested assistance of the US Department of Energy`s Atmospheric Release Advisory Capability (ARAC) in creating volcanic ash cloud aviation advisories for the region of the Philippine Islands. Through application of its three-dimensional material transport and diffusion models using AFGWC meteorological analysis and forecast wind fields ARAC developed extensive analysis and 12-hourly forecast ash cloud position advisories extending to 48 hours for a period of five days. The advisories consisted of ``relative`` ash cloud concentrations in ten layers (surface-5,000 feet, 5,000--10,000 feet and every 10,000 feet to 90,000 feet). The ash was represented as a log-normal size distribution of 10--200 {mu}m diameter solid particles. Size-dependent ``ashfall`` was simulated over time as the eruption clouds dispersed. Except for an internal experimental attempt to model one of the Mount Redoubt, Alaska, eruptions (12/89), ARAC had no prior experience in modeling volcanic eruption ash hazards. For the cataclysmic eruption of 15--16 June, the complex three-dimensional atmospheric structure of the region produced dramatically divergent ash cloud patterns. The large eruptions (> 7--10 km) produced ash plume clouds with strong westward transport over the South China Sea, Southeast Asia, India and beyond. The low-level eruptions (< 7 km) and quasi-steady-state venting produced a plume which generally dispersed to the north and east throughout the support period. Modeling the sequence of eruptions presented a unique challenge. Although the initial approach proved viable, further refinement is necessary and possible. A distinct need exists to quantify eruptions consistently such that ``relative`` ash concentrations relate to specific aviation hazard categories.
Sullivan, T.J.; Ellis, J.S. [Lawrence Livermore National Lab., CA (United States); Schalk, W.W.; Nasstrom, J.S. [EG and G, Inc., Pleasanton, CA (United States)
Supersaturation Intermittency in Turbulent Clouds
It is hypothesized that bursts of high supersaturation are produced in turbulent, convective clouds through interactions between cloud droplets and the small-scale structure of atmospheric turbulence. This hypothesis is based on the observation ...
Raymond A. Shaw
Mechanisms of Banner Cloud Formation
Banner clouds are clouds in the lee of steep mountains or sharp ridges. Their formation has previously been hypothesized as due to three different mechanisms: (i) vertical uplift in a lee vortex (which has a horizontal axis), (ii) adiabatic ...
Matthias Voigt; Volkmar Wirth
A Computer for the Clouds
Computer for the Clouds A Computer for the Clouds August 1, 2008 By PHILIP E. ROSS Columnist IEEE Spectrum: Inside Technology In May an IBM-built supercomputer called Roadrunner...
Remote Sensing of Cloud Parameters
Day and night mapping of the global distributions of the horizontal cloud covers and the corresponding cloud-top pressure levels are derived from the same set of infrared radiance data used to retrieve clear-column temperature profiles. General ...
Moustafa T. Chahine
Internet ware cloud computing :Challenges
After decades of engineering development and infrastructural investment, Internet connections have become commodity product in many countries, and Internet scale "cloud computing" has started to compete with traditional software business through its technological advantages and economy of scale. Cloud computing is a promising enabling technology of Internet ware Cloud Computing is termed as the next big thing in the modern corporate world. Apart from the present day software and technologies, cloud computing will have a growing impact on enterprise IT and business activities in many large organizations. This paper provides an insight to cloud computing, its impacts and discusses various issues that business organizations face while implementing cloud computing. Further, it recommends various strategies that organizations need to adopt while migrating to cloud computing. The purpose of this paper is to develop an understanding of cloud computing in the modern world and its impact on organizations and businesse...
Qamar, S; Singh, Mrityunjay
NIST Cloud Computing Related Publications
... Challenging Security Requirements for US Government Cloud Computing Adoption", December 2012 C. Dabrowski and K. Mills, "VM Leakage and ...
ARM - Field Campaign - Ground-based Cloud Tomography Experiment at SGP
govCampaignsGround-based Cloud Tomography Experiment at SGP govCampaignsGround-based Cloud Tomography Experiment at SGP Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Campaign : Ground-based Cloud Tomography Experiment at SGP 2009.05.26 - 2009.07.17 Lead Scientist : Dong Huang For data sets, see below. Description Knowledge of 3D cloud properties is pressingly needed in many research fields. One of the problems encountered when trying to represent 3D cloud fields in numerical models is that the existing techniques cannot provide necessary observations at the required spatial scale and resolution. We tested a new promising technique for measuring 3D cloud microphysical structure, called cloud microwave tomography, at the Southern Great Plains (SGP) site for one month in late April 2009. Five microwave scanning
Single-Column Modeling A Stratiform Cloud Parameterization for General Circulation Models
A Stratiform Cloud Parameterization A Stratiform Cloud Parameterization for General Circulation Models S. J. Ghan and L. R. Leung Pacific Northwest Laboratory Richland, WA 99352 C. C. Chuang and J. E. Penner Lawrence Livermore National Laboratory : Livermore. CA 94550 J. McCaa University of Washington Seattle, Washington The crude treatment of clouds in general circulation models (GCMs) is widely recognized as a major limitation in applying these models to predictions of global climate change. The purpose of this project is to develop in GCMs a stratiform cloud parameterization that expresses clouds in terms of bulk microphysical properties and their subgrid variability. Figure 1 summarizes the various cloud variables and their interactions. Precipitating cloud species are distinguished from non-precipitating species, and the liquid phase is
Contract RBAC in cloud computing
Cloud computing is a fast growing field, which is arguably a new computing paradigm. In cloud computing, computing resources are provided as services over the Internet and users can access resources based on their payments. The issue of access control ... Keywords: Cloud computing, Contract, Contract RBAC, Datacenter, RBAC
Hsing-Chung (Jack) Chen, Marsha Anjanette Violetta, Cheng-Ying Yang
Improving Utilization of Infrastructure Clouds
A key advantage of infrastructure-as-a-service (IaaS) clouds is providing users on-demand access to resources. To provide on-demand access, however, cloud providers must either significantly overprovision their infrastructure (and pay a high price for ... Keywords: Cloud Computing, Infrastructure-as-a-Service, High Throughput Computing
Paul Marshall; Kate Keahey; Tim Freeman
Parameterizing Vertically Coherent Cloud Distributions
A parameterization for specifying subgrid-scale cloud distributions in atmospheric models is developed. The fractional area of a grid-scale column in which clouds from two levels overlap (i.e., the cloud overlap probability) is described in terms ...
John W. Bergman; Philip J. Rasch
On the Exchange of Kinetic and Magnetic Energy Between Clouds and the Interstellar Medium
We investigate, through 2D MHD numerical simulations, the interaction of a uniform magnetic field oblique to a moving interstellar cloud. In particular we explore the transformation of cloud kinetic energy into magnetic energy as a result of field line stretching. Some previous simulations have emphasized the possible dynamical importance of a ``magnetic shield'' formed around clouds when the magnetic field is perpendicular to the cloud motion (Jones et al. 1996, Miniati et al. 1998). It was not clear, however, how dependent those findings were to the assumed field configuration and cloud properties. To expand our understanding of this effect, we examine several new cases by varing the magnetic field orientation angle with respect to the cloud motion (\\theta), the cloud-background density contrast, and the cloud Mach number. We show that in 2D and with \\theta large enough, the magnetic field tension can become dominant in the dynamics of the motion of high density contrast, low Mach number clouds. In such cases a significant fraction of cloud kinetic energy can be transformed into magnetic energy with the magnetic pressure at the cloud nose exceeding the ram pressure of the impinging flow. We derive a characteristic timescale for this process of energy ``conversion''. We find also that unless the cloud motion is highly aligned to the magnetic field, reconnection through tearing mode instabilities in the cloud wake limit the formation of a strong flux rope feature following the cloud. Finally we attempt to interpret some observational properties of the magnetic field in view of our results.
Francesco Miniati; T. W. Jones; Dongsu Ryu
A Smooth Cloud Model
In this paper a large-eddy �smooth� cloud (SC) model will be presented with smooth implying that the entire model converges under a Newton-based solution procedure or that time scales within the SC model are being resolved. Besides ensuring that ...
J. M. Reisner; C. A. Jeffery
Slide 1
Performance of Forecasting Models Across the North Slope of Alaska Performance of Forecasting Models Across the North Slope of Alaska During the Mixed-Phase Arctic Cloud Experiment Victor Yannuzzi, Eugene Clothiaux, Johannes Verlinde and Jerry Harrington The Pennsylvania State University Introduction The Mixed-Phase Arctic Cloud Experiment (MPACE) was conducted across the North Slope of Alaska (NSA) from September 27 through October 22, 2004. The experiment was funded by the Department of Energy (DOE)-Atmospheric Radiation Measurement (ARM) program to study the microphysics, radiative properties, thermodynamics, and life cycle of mixed-phase clouds in the Arctic. A focused set of observation stations and soundings were in place across the NSA (figure 1) where conditions could be expected to produce low-level mixed-phase clouds on
Effects of aerosols on deep convective cumulus clouds
This work investigates the effects of anthropogenic aerosols on deep convective clouds and the associated radiative forcing in the Houston area. The Goddard Cumulus Ensemble model (GCE) coupled with a spectral-bin microphysics is employed to investigate the aerosol effects on clouds and precipitation. First, aerosol indirect effects on clouds are separately investigated under different aerosol compositions, concentrations and size distributions. Then, an updated GCE model coupled with the radiative transfer and land surface processes is employed to investigate the aerosol radiative effects on deep convective clouds. The cloud microphysical and macrophysical properties change considerably with the aerosol properties. With varying the aerosol composition from only (NH4)2SO4, (NH4)2SO4 with soluble organics, to (NH4)2SO4 with slightly soluble organics, the number of activated aerosols decreases gradually, leading to a decrease in the cloud droplet number concentration (CDNC) and an increase in the droplet size. Ice processes are more sensitive to the changes of aerosol chemical properties than the warm rain processes. The most noticeable effect of increasing aerosol number concentrations is an increase of CDNC and cloud water content but a decrease in droplet size. It is indicated that the aerosol indirect effect on deep convection is more pronounced in relatively clean air than in heavily polluted air. The aerosol effects on clouds are strongly dependent on RH: the effect is very significant in humid air. Aerosol radiative effects (ARE) on clouds are very pronounced for mid-visible single-scattering albedo (SSA) of 0.85. Relative to the case without the ARE, cloud fraction and optical depth decrease by about 18% and 20%, respectively. The daytime-mean direct forcing is about 2.2 W m-2 at the TOA and -17.4 W m-2 at the surface. The semi-direct forcing is positive, about 10 and 11.2 W m-2 at the TOA and surface, respectively. Aerosol direct and semi-direct effects are very sensitive to SSA. The cloud fraction, optical depth, convective strength, and precipitation decrease with the increase of absorption, resulting from a more stable atmosphere due to enhanced surface cooling and atmospheric heating.
Fan, Jiwen
ARM - Field Campaign - Biogenic Aerosols - Effects on Clouds and Climate:
govCampaignsBiogenic Aerosols - Effects on Clouds and Climate: govCampaignsBiogenic Aerosols - Effects on Clouds and Climate: FIGAERO-ToF-CIMS Instrument in Hyytiala with AMF-2 Related Campaigns Biogenic Aerosols- Effects on Clouds and Climate 2014.02.01, Petäjä, AMF Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Campaign : Biogenic Aerosols - Effects on Clouds and Climate: FIGAERO-ToF-CIMS Instrument in Hyytiala with AMF-2 2014.04.01 - 2014.06.01 Lead Scientist : Joel Thornton Description The ultimate goal of this work is to connect field and laboratory observations of organic aerosol chemical and physical properties during the nascent growth stage to the diurnal and vertical distributions of aerosol abundance measured over the boreal forest by the ARM Mobile Facility 2
MODTRAN cloud and multiple scattering upgrades with application to AVIRIS
Recent upgrades to the MODTRAN atmospheric radiation code improve the accuracy of its radiance predictions, especially in the presence of clouds and thick aerosols, and for multiple scattering in regions of strong molecular line absorption. The current public-released version of MODTRAN (MODTRAN3.7) features a generalized specification of cloud properties, while the current research version of MODTRAN (MODTRAN4) implements a correlated-k (CK) approach for more accurate calculation of multiple scattered radiance. Comparisons to cloud measurements demonstrate the viability of the CK approach. The impact of these upgrades on predictions for AVIRIS viewing scenarios is discussed for both clear and clouded skies; the CK approach provides refined predictions for AVIRIS nadir and near-nadir viewing.
Berk, A.; Bernstein, L.S.; Acharya, P.K.; Robertson, D.C.; Adler-Golden, S.M. [Spectral Sciences, Inc., Burlington, MA (United States)] [Spectral Sciences, Inc., Burlington, MA (United States); Anderson, G.P.; Chetwynd, J.H. [Air Force Research Lab., Hanscom AFB, MA (United States). Geophysics Directorate] [Air Force Research Lab., Hanscom AFB, MA (United States). Geophysics Directorate
Radiative Importance of Thin Liquid Water Clouds
Program Program Accomplishments of the Cloud Properties Working Group (CPWG) August 2006 Cloud Radiative Forcing at the ARM Climate Research Facility: Using ARM Data to Establish Testable Metrics for GCM Predictions of Cloud Feedback Gerald Mace University of Utah, Salt Lake City, Utah The scientific underpinning of the Atmospheric Radiation Measurement (ARM) Program is largely based on the premise that long term ground-based measurements of certain quantities provide information sufficient to test the skill of general circulation models (GCMs) to predict radiative heating and cloud feedbacks (Stokes and Schwartz, 1994; Ackerman and Stokes, 2003). This hypothesis is based on the assumption that some set of long-term ground-based measurements provide sufficient information to characterize the physical state of the atmospheric
Mixed-Phase Cloud Radiative Properties from M-PACE Microphysical Retrievals Mixed-Phase Cloud Radiative Properties from M-PACE Microphysical Retrievals Download a printable PDF Submitter: de Boer, G., University of Colorado, Boulder/CIRES Area of Research: Radiation Processes Working Group(s): Cloud Life Cycle Journal Reference: de Boer G, WD Collins, S Menon, and CN Long. 2011. "Using surface remote sensors to derive radiative characteristics of mixed-phase clouds: An example from M-PACE." Atmospheric Chemistry and Physics, 11, doi: 10.5194/acp-11-11937-2011. Measured and retrieved cloud properties on 10 October 2004. Included are (top to bottom) AHSRL bacscatter cross-section, AHSRL depolarization ratio, MMCR reflectivity, and profiles of liquid water content (LWC), ice water content (IWC), and liquid (r_{e,liq}) and ice (r$_{e,ice}$) effective
MAGIC: Marine ARM GPCI Investigation of Clouds
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Lewis, ER; Wiscombe, WJ; Albrecht, BA; Bland, GL; Flagg, CN; Klein, SA; Kollias, P; Mace, G; Reynolds, RM; Schwartz, SE; Siebesma, AP; Teixeira, J; Wood, R; Zhang, M
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