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Office of Scientific and Technical Information
Cloud Properties Working Group Low Clouds Update
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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)
GEWEX Cloud System Study (GCSS) Working Group 4: Precipitating Convective Cloud Systems
Science Conference Proceedings (OSTI)
The authors present the objectives of the working group on precipitating convective cloud systems. These center on developing physically based parameterizations for global models in which basic research into the large-scale role of cloud systems ...
Mitchell W. Moncrieff; Steven K. Krueger; David Gregory; Jean-Luc Redelsperger; Wei-Kuo Tao
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
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
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
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
Preliminary definition of Barstow standard cloud model
DOE Green Energy (OSTI)
The motion of cloud shadows across a collector field for a central receiver solar power plant can affect the design of such a facility. Cloud models were developed to be used for basis of design in technology areas. The first effect, that of the temperature gradient, is simulated by postulating the worst case cloud situation. The cyclic effects require realistic cloud shadow time histories for simulation. Cloud shadow models were developed to determine probable cloud type, the cloud area and shape, cloud velocity and cloud-to-cloud spacing. The probability of cloud occurrence is estimated. A collector field computer program is run to determine the effect of cloud variables on collector field power delivery capability. Recommendation of cloud models to be used for basis of design are then made.
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:...
Cloud service selection based on variability modeling
The selection among Cloud services is a recent problem in research and practice. The diversity of decision-relevant criteria, configurability of Cloud services and the need to involve human decision-makers require holistic support through models, methodologies ... Keywords: cloud service selection, decision-making, feature modeling, variability modeling
Erik Wittern; J�rn Kuhlenkamp; Michael Menzel
A Cloud-Resolving Model with an Adaptive Vertical Grid for Boundary Layer Clouds
Accurate cloud-resolving model simulations of cloud cover and cloud water content for boundary layer clouds are difficult to achieve without vertical grid spacing well below 100 m, especially for inversion-topped stratocumulus. The need for fine ...
Roger Marchand; Thomas Ackerman
Simulation of Cloud Microphysical and Chemical Processes Using a Multicomponent Framework. Part I: Description of the Microphysical Model
A detailed microphysical and chemical cloud model has been developed to investigate the redistribution of atmospheric trace substances through cloud processes. A multicomponent categorization scheme is used to group cloud particles into different ...
Jen-Ping Chen; Dennis Lamb
A Three-Dimensional Cloud Chemistry Model
A cloud chemistry model is formulated in term of continuity equations for chemical species in the aqueous and aqueous phases within the cloud. The model includes scavenging of SO2, HNO3, HN3, H2O3, and sulphate aerosol particles. Calculations ...
Andre Tremblay; Henry Leighton
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
A Lightning Parameterization for Numerical Cloud Models
A new lightning parameterization has been developed to enable cloud models to simulate the location and structure of individual lightning flashes more realistically. To do this, three aspects of previous parameterizations have been modified: 1) ...
Donald R. MacGorman; Jerry M. Straka; Conrad L. Ziegler
Ensemble Cloud Model Applications to Forecasting Thunderstorms
A cloud model ensemble forecasting approach is developed to create forecasts that describe the range and distribution of thunderstorm lifetimes that may be expected to occur on a particular day. Such forecasts are crucial for anticipating severe ...
Kimberly L. Elmore; David J. Stensrud; Kenneth C. Crawford
Cloud Thermodynamic Models in Saturation Point Coordinates
One-dimensional thermodynamic models for cloud-environment mixing, evaporation into downdrafts and precipitation from updrafts are presented in a parallel treatment using convective pressure scales and saturation point coordinates. This common ...
Alan K. Betts
Cloud Predictions Diagnosed from Global Weather Model Forecasts
The U.S. Air Force has a long history of investment in cloud analysis and prediction operations. Their need for accurate cloud cover information has resulted in routine production of global cloud analyses (from their RTNEPH analysis model) and ...
Donald C. Norquist
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
Stable Isotopes in Hailstones. Part I: The Isotopic Cloud Model
Equations describing the isotopic balance between five water species (vapor, cloud water, rainwater, cloud ice and graupel)have been incorporated into a one-dimensional steady-state cloud model. The isotope contents of the various water ...
B. Federer; N. Brichet; J. Jouzel
A Global Cloud Resolving Model Goals
Cloud Resolving Model Cloud Resolving Model Goals Uniform global horizontal grid spacing of 4 km or better ("cloud permitting") 100 or more layers up to at least the stratopause Parameterizations of microphysics, turbulence (including small clouds), and radiation Execution speed of at least several simulated days per wall-clock day on immediately available systems Annual cycle simulation by end of 2011. Motivations Parameterizations are still problematic. There are no spectral gaps. The equations themselves change at high resolution. GCRMs will be used for NWP within 10 years. GCRMs will be used for climate time-slices shortly thereafter. It's going to take some time to learn how to do GCRMs well. Scaling Science Length, Spatial extent, #Atoms, Weak scaling Time scale
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
A Review of Cloud Modeling in Weather Modification
The numerical modeling of clouds has a history almost as long as the modern-day concepts of the seeding of clouds. The various models and theoretical developments emerging from the model results are reviewed in this paper. Significant advances ...
Harold D. Orville
Nonhydrostatic icosahedral atmospheric model (NICAM) for global cloud resolving simulations
A new type of ultra-high resolution atmospheric global circulation model is developed. The new model is designed to perform ''cloud resolving simulations'' by directly calculating deep convection and meso-scale circulations, which play key roles not ... Keywords: Aqua-planet experiments, Atmospheric general circulation models, Cloud clusters, Cloud resolving model, Icosahedral grids, Nonhydrostatic model
M. Satoh; T. Matsuno; H. Tomita; H. Miura; T. Nasuno; S. Iga
Application of a Cloud Model to Cooling Tower Plumes and Clouds
A steady-state, one-dimensional cloud model has been modified to simulate the growth of plumes (both wet and dry) and clouds from natural and forced draft cooling towers. The modifications to the cloud model are discussed and comparisons are made ...
Harold D. Orville; John H. Hirsch; Laurence E. May
A Comparison of Seeded and Nonseeded Orographic Cloud Simulations with an Explicit Cloud Model
Ice initiation by specific cloud seeding aerosols, quantified in laboratory studies, has been formulated for use in mesoscale numerical cloud models. This detailed approach, which explicitly represents artificial ice nuclei activation, is unique ...
Michael P. Meyers; Paul J. Demott; William R. Cotton
Cirrus Cloud Ice Water Content Radar Algorithm Evaluation Using an Explicit Cloud Microphysical Model
A series of cirrus cloud simulations performed using a model with explicit cloud microphysics is applied to testing ice water content retrieval algorithms based on millimeter-wave radar reflectivity measurements. The simulated ice particle size ...
Kenneth Sassen; Zhien Wang; Vitaly I. Khvorostyanov; Graeme L. Stephens; Angela Bennedetti
Cloud-Resolving Model Simulation and Mosaic Treatment of Subgrid Cloud-Radiation Interaction
Cloud-Resolving Model Simulation and Mosaic Treatment Cloud-Resolving Model Simulation and Mosaic Treatment of Subgrid Cloud-Radiation Interaction X. Wu Department of Geological and Atmospheric Sciences Iowa State University Ames, Iowa X.-Z. Liang Illinois State Water Survey University of Illinois at Urbana-Champaign Champaign, Illinois Introduction Improving the representation of cloud-radiation interaction is a major challenge for the global climate simulation. The development of cloud-resolving models (CRMs) and the extensive Atmospheric Radiation Measurements (ARMs) provide a unique opportunity for shading some lights on this problem. Current general circulation models (GCMs) predict cloud cover fractions and hydrometeor concentra- tions only in individual model layers, where clouds are assumed to be horizontally homogeneous in a
A Community Atmosphere Model with Superparameterized Clouds
SciTech Connect
In 1999, National Center for Atmospheric Research (NCAR) scientists Wojciech Grabowski and Piotr Smolarkiewicz created a "multiscale" atmospheric model in which the physical processes associated with clouds were represented by running a simple high-resolution model within each grid column of a lowresolution global model. In idealized experiments, they found that the multiscale model produced promising simulations of organized tropical convection, which other models had struggled to produce. Inspired by their results, Colorado State University (CSU) scientists Marat Khairoutdinov and David Randall created a multiscale version of the Community Atmosphere Model (CAM). They removed the cloud parameterizations of the CAM, and replaced them with Khairoutdinov's high-resolution cloud model. They dubbed the embedded cloud model a "super-parameterization," and the modified CAM is now called the "SP-CAM." Over the next several years, many scientists, from many institutions, have explored the ability of the SP-CAM to simulate tropical weather systems, the day-night changes of precipitation, the Asian and African monsoons, and a number of other climate processes. Cristiana Stan of the Center for Ocean-Land-Atmosphere Interactions found that the SP-CAM gives improved results when coupled to an ocean model, and follow-on studies have explored the SP-CAM's utility when used as the atmospheric component of the Community Earth System Model. Much of this research has been performed under the auspices of the Center for Multiscale Modeling of Atmospheric Processes, a National Science Foundation (NSF) Science and Technology Center for which the lead institution is CSU.
Randall, David; Branson, Mark; Wang, Minghuai; Ghan, Steven J.; Craig, Cheryl; Gettelman, A.; Edwards, Jim
Testing Statistical Cloud Scheme Ideas in the GFDL Climate Model
Testing Statistical Cloud Scheme Ideas in the GFDL Climate Model Testing Statistical Cloud Scheme Ideas in the GFDL Climate Model Klein, Stephen Lawrence Livermore National Laboratory Pincus, Robert NOAA-CIRES Climate Diagnostics Center Category: Modeling Statistical cloud schemes (or assumed probability distribution function cloud schemes) are attractive because they provide a way to implement horizontal sub-grid scale cloud heterogeneity in a self-consistent way between physical parameterizations of the a climate model, such as radiation and cloud microphysics. In this work, we will present results dealing with two aspects of our ongoing work towards the implementation of statistical cloud scheme ideas in the climate model of Geophysical Fluid Dynamics Laboratory. First, we will address the representation of cloud
A Numerical Study of Cirrus Clouds. Part I: Model Description
This article, the first of a two-part series, presents a detailed description of a two-dimensional numerical cloud model directed toward elucidating the physical processes governing the evolution of cirrus clouds. The two primary scientific ...
Hui-Chun Liu; Pao K. Wang; Robert E. Schlesinger
Confronting Models with Data: The GEWEX Cloud Systems Study
The Global Energy and Water Cycle Experiment (GEWEX) Cloud System Study (GCSS) was organized to promote the development of improved parameterizations of cloud systems for use in climate and numerical weather prediction models, with an emphasis on ...
David Randall; Steven Krueger; Christopher Bretherton; Judith Curry; Peter Duynkerke; Mitchell Moncrieff; Brian Ryan; David Starr; Martin Miller; William Rossow; George Tselioudis; Bruce Wielicki
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
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.
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
A leasing instances based billing model for cloud computing
As a new technology in IT industry, cloud computing has been much focused by both academia and industry. And many topics in cloud computing are under study. However, as one of the most important issue, billing and pricing has been not so much concerned. ... Keywords: billing model, cloud computing, leasing instances, pricing
Qin Yuan; Zhixiang Liu; Junjie Peng; Xing Wu; Jiandun Li; Fangfang Han; Qing Li; Wu Zhang; Xinjin Fan; Shengyuan Kong
Bulk Parameterization of the Snow Field in a Cloud Model
A two-dimensional, time-dependent cloud model has been used to simulate a moderate intensity thunderstorm for the High Plains region. Six forms of water substance (water vapor, cloud water, cloud ice, rain, snow and hail, i.e., graupel) are ...
Yuh-Lang Lin; Richard D. Farley; Harold D. Orville
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
Cloud-Resolving Modeling of Tropical Cloud Systems during Phase III of GATE. Part I: Two-Dimensional Experiments
A formal framework is established for the way in which cloud-resolving numerical models are used to investigate the role of precipitating cloud systems in climate and weather forecasting models. Emphasis is on models with periodic lateral ...
Wojciech W. Grabowski; Xiaoqing Wu; Mitchell W. Moncrieff
Modeling the Interactions between Aerosols and Liquid Water Clouds with a Self-Consistent Cloud Scheme in a General Circulation Model
To model aerosol�cloud interactions in general circulation models (GCMs), a prognostic cloud scheme of cloud liquid water and amount is expanded to include droplet number concentration (Nd) in a way that allows them to be calculated using the ...
Yi Ming; V. Ramaswamy; Leo J. Donner; Vaughan T. J. Phillips; Stephen A. Klein; Paul A. Ginoux; Larry W. Horowitz
Posters Cloud Parameterizations in Global Climate Models: The...
3 Posters Cloud Parameterizations in Global Climate Models: The Role of Aerosols J. E. Penner and C. C. Chuang Lawrence Livermore National Laboratory Livermore, California...
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
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
Evaluation of Cloud Type Occurrences and Radiative Forcings Simulated by a Cloud Resolving Model Using Observations from Sa...
Cloud Type Occurrences Cloud Type Occurrences and Radiative Forcings Simulated by a Cloud Resolving Model Using Observations from Satellite and Cloud Radar Y. Luo and S. K. Krueger University of Utah Salt Lake City, Utah Introduction Because of both the various effects clouds exert on the earth-atmospheric system and the cloud feedback, correct representations of clouds in numerical models are critical for accurate climate modeling and weather forecast. Unfortunately, determination of clouds and their radiative feedback processes is still the weakest component of current general circulation models (e.g., Senior and Mitchell 1993, Cess et al. 1996). Using radiative fluxes at the top of atmosphere (TOA) available from satellite observations made by the Earth Radiation Budget Experiment (ERBE; Barkstrom 1984), one could assess cloud radiative effects
Efficient data IO for a Parallel Global Cloud Resolving Model
Execution of a Global Cloud Resolving Model (GCRM) at target resolutions of 2-4 km will generate, at a minimum, 10s of Gigabytes of data per variable per snapshot. Writing this data to disk, without creating a serious bottleneck in the execution of the ... Keywords: Data formatting, Geodesic grid, Global Cloud Resolving Model, Grid Specifications, High performance IO, Parallel IO libraries
Bruce Palmer; Annette Koontz; Karen Schuchardt; Ross Heikes; David Randall
Validation of Cloud-Resolving Model Background Data for Cloud Data Assimilation
Results from a cloud-resolving model are systematically compared with a variety of observations, both ground based and satellite, in order to better understand the mean background errors and their correlations. This is a step in the direction of ...
Rosanne Polkinghorne; Tomislava Vukicevic; K. Franklin Evans
Statistical representation of clouds in climate models
novel approach for representing novel approach for representing ice microphysics in bin and bulk schemes: Application to TWP-ICE deep convection Hugh Morrison and Wojciech Grabowski National Center for Atmospheric Research ARM STM, Monday, April 1, 2009 -1) Uncertainty of ice initiation processes -2) Wide range of ice particle characteristics (e.g., shape, effective density) -3) No clear separation of physical processes for small and large crystals The treatment of ice microphysics has a large impact on model simulations, e.g., precipitation, interactions with dynamics, radiation, etc. However, it is complicated by: Pristine ice crystals, grown by diffusion of water vapor Snowflakes, grown by aggregation Pruppacher and Klett Rimed ice crystals (accretion of supercooled cloud water) Graupel (heavily
A comparison of cloud microphysical quantities with forecasts from cloud prediction models
Numerical weather prediction models (ECMWF, NCEP) are evaluated using ARM observational data collected at the Southern Great Plains (SGP) site. Cloud forecasts generated by the models are compared with cloud microphysical quantities, retrieved using a variety of parameterizations. Information gained from this comparison will be utilized during the FASTER project, as models are evaluated for their ability to reproduce fast physical processes detected in the observations. Here the model performance is quantified against the observations through a statistical analysis. Observations from remote sensing instruments (radar, lidar, radiometer and radiosonde) are used to derive the cloud microphysical quantities: ice water content, liquid water content, ice effective radius and liquid effective radius. Unfortunately, discrepancies in the derived quantities arise when different retrieval schemes are applied to the observations. The uncertainty inherent in retrieving the microphysical quantities using various retrievals is estimated from the range of output microphysical values. ARM microphysical retrieval schemes (Microbase, Mace) are examined along with the CloudNet retrieval processing of data from the ARM sites for this purpose. Through the interfacing of CloudNet and �ARM� processing schemes an ARMNET product is produced and employed as accepted observations in the assessment of cloud model predictions.
Dunn, M.; Jensen, M.; Hogan, R.; O�Connor, E.; Huang, D.
Antarctic Clouds and Radiation within the NCAR Climate Models
To evaluate and improve the treatment of clouds and radiation by the climate models of the National Center for Atmospheric Research (NCAR), simulations by the NCAR Community Climate Model version 3 (CCM3), as well as the recently released ...
Keith M. Hines; David H. Bromwich; Philip J. Rasch; Michael J. Iacono
Generation of Infrasound by Evaporating Hydrometeors in a Cloud Model
The dynamical core of the Regional Atmospheric Modeling System has been tailored to simulate the infrasound of vortex motions and diabatic cloud processes in a convective storm. Earlier studies have shown that the customized model (c-RAMS) ...
David A. Schecter; Melville E. Nicholls
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
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
Response of Upper Clouds in Global Warming Experiments Obtained Using a Global Nonhydrostatic Model with Explicit Cloud Processes
Using a global nonhydrostatic model with explicit cloud processes, upper-cloud changes are investigated by comparing the present climate condition under the perpetual July setting and the global warming condition, in which the sea surface ...
Masaki Satoh; Shin-ichi Iga; Hirofumi Tomita; Yoko Tsushima; Akira T. Noda
Diagnosis of the Warm Rain Process in Cloud-Resolving Models Using Joint CloudSat and MODIS Observations
This study examines the warm rain formation process in global and regional cloud-resolving models. Methodologies developed to analyze CloudSat and Moderate Resolution Imaging Spectroradiometer (MODIS) satellite observations are employed to ...
Kentaroh Suzuki; Graeme L. Stephens; Susan C. van den Heever; Takashi Y. Nakajima
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
Cumulus Entrainment and Cloud Droplet Spectra: A Numerical Model within a Two-Dimensional Dynamical Framework
A simple numerical model designed to predict the evolution of cloud droplet spectra with special emphasis on the role of entrainment is developed for a case of nonprecipitating cloud. The model assumes that the cloud water mixing ratio at any ...
Jean-Louis Brenguier; Wojciech W. Grabowski
LLNL Chemical Kinetics Modeling Group
The LLNL chemical kinetics modeling group has been responsible for much progress in the development of chemical kinetic models for practical fuels. The group began its work in the early 1970s, developing chemical kinetic models for methane, ethane, ethanol and halogenated inhibitors. Most recently, it has been developing chemical kinetic models for large n-alkanes, cycloalkanes, hexenes, and large methyl esters. These component models are needed to represent gasoline, diesel, jet, and oil-sand-derived fuels.
Pitz, W J; Westbrook, C K; Mehl, M; Herbinet, O; Curran, H J; Silke, E J
[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.
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
Infrared Propagation Modeling beneath Marine Stratus Clouds
Airborne measurements of aerosol size distributions are used to determine the vertical profiles of infrared (IR) extinction and absorption coefficients and asymmetry factors in eight different maritime stratus cloud regimes during unstable ...
H. G. Hughes; C. R. Zeisse
Predictability Mysteries in Cloud-Resolving Models
The rapid amplification of small-amplitude perturbations by the chaotic nature of the atmospheric dynamics intrinsically limits the skill of deterministic weather forecasts. In this study, limited-area cloud-resolving numerical weather prediction ...
Cathy Hohenegger; Daniel L�thi; Christoph Sch�r
Hail Growth in a Three-Dimensional Cloud Model
A hailstone growth model is developed. The changes in hailstone density due to varying riming densities are considered. The contributions of evaporation to melting as well as wet growth (which cannot be neglected when the cloud temperature is ...
Jia-Liu Xu
Parameterization of Bulk Condensation in Numerical Cloud Models
The accuracy of the moist saturation adjustment scheme has been evaluated using a three-dimensional explicit microphysical cloud model. It was found that the error in saturation adjustment depends strongly on the CCN concentration in the ambient ...
Yefim L. Kogan; William J. Martin
Chaff Seeding Effects in a Dynamical-Electrical Cloud Model
A two-dimensional, slab-symmetric, time-dependent cloud model has been devised to simulate deep convection in the atmosphere. The dynamics and thermodynamics of deep convection are prescribed and the microphysics of the liquid phase is ...
John H. Helsdon Jr.
A New Double-Moment Microphysics Parameterization for Application in Cloud and Climate Models. Part II: Single-Column Modeling of Arctic Clouds
E-Print Network (OSTI)
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
Aerosol Influence on Cloud Microphysics Examined by Satellite Measurements and Chemical Transport Modeling
Anthropogenic aerosols are hypothesized to decrease cloud drop radius and increase cloud droplet number concentration enhancing cloud optical depth and albedo. Here results have been used from a chemical transport model driven by the output of a ...
Harshvardhan; S. E. Schwartz; C. M. Benkovitz; G. Guo
A Test of the Simulation of Tropical Convective Cloudiness by a Cloud-Resolving Model
A methodology is described for testing the simulation of tropical convective clouds by models through comparison with observations of clouds and precipitation from earth-orbiting satellites. Clouds are divided into categories that represent ...
Mario A. Lopez; Dennis L. Hartmann; Peter N. Blossey; Robert Wood; Christopher S. Bretherton; Terence L. Kubar
Implementation of the Cloud Prediction Scheme in the Eta Model at NCEP
An explicit cloud prediction scheme has been developed and incorporated into the Eta Model at the National Centers for Environmental Prediction (NCEP) to improve the cloud and precipitation forecasts. In this scheme, the cloud liquid water and ...
Qingyun Zhao; Thomas L. Black; Michael E. Baldwin
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
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...
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
Radiation Parameterization for Three-Dimensional Inhomogeneous Cirrus Clouds Applied to ARM Data and Climate Models
OAK-B135 (a) We developed a 3D radiative transfer model to simulate the transfer of solar and thermal infrared radiation in inhomogeneous cirrus clouds. The model utilized a diffusion approximation approach (four-term expansion in the intensity) employing Cartesian coordinates. The required single-scattering parameters, including the extinction coefficient, single-scattering albedo, and asymmetry factor, for input to the model, were parameterized in terms of the ice water content and mean effective ice crystal size. The incorporation of gaseous absorption in multiple scattering atmospheres was accomplished by means of the correlated k-distribution approach. In addition, the strong forward diffraction nature in the phase function was accounted for in each predivided spatial grid based on a delta-function adjustment. The radiation parameterization developed herein is applied to potential cloud configurations generated from GCMs to investigate broken clouds and cloud-overlapping effects on the domain-averaged heating rate. Cloud inhomogeneity plays an important role in the determination of flux and heating rate distributions. Clouds with maximum overlap tend to produce less heating than those with random overlap. Broken clouds show more solar heating as well as more IR cooling as compared to a continuous cloud field (Gu and Liou, 2001). (b) We incorporated a contemporary radiation parameterization scheme in the UCLA atmospheric GCM in collaboration with the UCLA GCM group. In conjunction with the cloud/radiation process studies, we developed a physically-based cloud cover formation scheme in association with radiation calculations. The model clouds were first vertically grouped in terms of low, middle, and high types. Maximum overlap was then used for each cloud type, followed by random overlap among the three cloud types. Fu and Liou's 1D radiation code with modification was subsequently employed for pixel-by-pixel radiation calculations in the UCLA GCM. We showed that the simulated cloud cover and OLR fields without special tuning are comparable to those of ISCCP dataset and the results derived from radiation budget experiments. Use of the new radiation and cloud schemes enhances the radiative warming in the middle to upper tropical troposphere and alleviates the cold bias in the UCLA atmospheric GCM. We also illustrated that ice crystal size and cloud inhomogeneous are significant factors affecting the radiation budgets at the top of the atmosphere and the surface (Gu et al. 2003). (c) An innovative approach has been developed to construct a 3D field of inhomogeneous clouds in general and cirrus in particular in terms of liquid/ice water content and particle size on the basis of a unification of satellite and ground-based cloud radar data. Satellite remote sensing employing the current narrow-band spectro-radiometers has limitation and only the vertically integrated cloud parameters (optical depth and mean particle size) can be determined. However, by combining the horizontal cloud mapping inferred from satellites with the vertical structure derived from the profiling Doppler cloud radar, a 3D cloud field can be constructed. This represents a new conceptual approach to 3D remote sensing and imaging and offers a new perspective in observing the cloud structure. We applied this novel technique to AVHRR/NOAA satellite and mm-wave cloud radar data obtained from the ARM achieve and assessed the 3D cirrus cloud field with the ice crystal size distributions independently derived from optical probe measurements aboard the University of North Dakota Citation. The retrieved 3D ice water content and mean effective ice crystal size involving an impressive cirrus cloud occurring on April 18, 1997, are shown to be comparable to those derived from the analysis of collocated and coincident in situ aircraft measurements (Liou et al. 2002). (d) Detection of thin cirrus with optical depths less than 0.5, particularly those occurring i n the tropics remains a fundamental problem in remote sensing. We developed a new detection scheme for the
Kuo-Nan Liou
The Use of a Two-Dimensional, Time-Dependent Cloud Model to Predict Convective and Stratiform Clouds and Precipitation
A two-dimensional, time-dependent cloud model has been used in two field projects to forecast the convective development during the day from the morning sounding. In effect, the cloud model gives a dynamic analysis of the sounding as affected by ...
Fred J. Kopp; Harold D. Orville
This work is the continuation of [4] our earlier studies on electron cloud (EC) simulations for the medium energy electron-ion collider (MEIC) envisioned at Jefferson Lab beyond the 12 GeV upgrade of CEBAF. In this paper, we study the EC saturation density with various MEIC operational parameters. The details of the study shows saturation of line density 1.7 nC/m and tune shift per unit length 4.9 x 10{sup -7} m{sup -1}.
S. Ahmed, B. Yunn, J. Dolph, T. Satogata, G.A. Krafft
Visualization and Modeling Working Group
During the 2005 Hurricane season, many consequence predictions were available from 36 to 96 hours before landfalls, via the Department of Energy�s Visualization and Modeling Working Group (VMWG). Real-time data can be tapped by local officials and utilities, and can also be accessed for post-event regulatory audits. An overview of VMWG�s models, results and uses will be presented.
Fernandez, S.J. (LANL); Dodrill, K.A.
Kinetics of Cloud Drop Formation and Its Parameterization for Cloud and Climate Models
To study the kinetics of drop nucleation in clouds, the integro�differential equation for integral water supersaturation in cloud is derived and analyzed. Solving the supersaturation equation with an algebraic form of the cloud condensation ...
Vitaly I. Khvorostyanov; Judith A. Curry
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.
A Comparison of Simulated Cloud Radar Output from the Multiscale Modeling Framework Global Climate Model with CloudSat Cloud Radar Observations
Over the last few years a new type of global climate model (GCM) has emerged in which a cloud-resolving model is embedded into each grid cell of a GCM. This new approach is frequently called a multiscale modeling framework (MMF) or superparameterization. In this article we present a comparison of MMF output with radar observations from the NASA CloudSat mission, which uses a near-nadir-pointing millimeter-wavelength radar to probe the vertical structure of clouds and precipitation. We account for radar detection limits by simulating the 94 GHz radar reflectivity that CloudSat would observe from the high-resolution cloud-resolving model output produced by the MMF. Overall, the MMF does a good job of reproducing the broad pattern of tropical convergence zones, subtropical belts, and midlatitude storm tracks, as well as their changes in position with the annual solar cycle. Nonetheless, the comparison also reveals a number of model shortfalls including (1) excessive hydrometeor coverage at all altitudes over many convectively active regions, (2) a lack of low-level hydrometeors over all subtropical oceanic basins, (3) excessive low-level hydrometeor coverage (principally precipitating hydrometeors) in the midlatitude storm tracks of both hemispheres during the summer season (in each hemisphere), and (4) a thin band of low-level hydrometeors in the Southern Hemisphere of the central (and at times eastern and western) Pacific in the MMF, which is not observed by CloudSat. This band resembles a second much weaker ITCZ but is restricted to low levels.
Marchand, Roger T.; Haynes, J. M.; Mace, Gerald G.; Ackerman, Thomas P.; Stephens, Graeme L.
Elucidating Model Inadequacies in a Cloud Parameterization by Use of an Ensemble-Based Calibration Framework
Every cloud parameterization contains structural model errors. The source of these errors is difficult to pinpoint because cloud parameterizations contain nonlinearities and feedbacks. To elucidate these model inadequacies, this paper uses a ...
Jean-Christophe Golaz; Vincent E. Larson; James A. Hansen; David P. Schanen; Brian M. Griffin
Tropical Water Vapor and Cloud Feedbacks in Climate Models: A Further Assessment Using Coupled Simulations
By comparing the response of clouds and water vapor to ENSO forcing in nature with that in Atmospheric Model Intercomparison Project (AMIP) simulations by some leading climate models, an earlier evaluation of tropical cloud and water vapor ...
De-Zheng Sun; Yongqiang Yu; Tao Zhang
Explicit Cloud-Scale Models for Operational Forecasts: A Note of Caution
As computational capacity has increased, cloud-scale numerical models are slowly being modified from pure research tools to forecast tools. Previous studies that used cloud-scale models as explicit forecast tools, in much the same way as a ...
A Warm-Bin�Cold-Bulk Hybrid Cloud Microphysical Model
This study describes a newly developed bin�bulk hybrid cloud microphysical model named MSSG-Bin, which has been implemented in the Multi-Scale Simulator for the Geoenvironment (MSSG). In the hybrid approach, a spectral bin scheme is used for ...
Ryo Onishi; Keiko Takahashi
Operational Ensemble Cloud Model Forecasts: Some Preliminary Results
From 15 July through 30 September of 2001, an ensemble cloud-scale model was run for the Storm Prediction Center on a daily basis. Each ensemble run consisted of 78 members whose initial conditions were derived from the 20-km Rapid Update Cycle ...
Kimberly L. Elmore; Steven J. Weiss; Peter C. Banacos
Intercomparison of model simulations of mixed-phase clouds observed during the ARM Mixed-Phase Arctic Cloud Experiment. Part I: Single layer 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
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
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
Shupe, Matthew
Cloud-Resolving Model Simulations and a Simple Model of an Idealized Walker Cell
An idealized Walker cell with prescribed sea surface temperature (SST) and prescribed radiative cooling is studied using both a two-dimensional cloud-resolving model (CRM) and a simple conceptual model. In the CRM, for the same SST distribution, ...
Jonathan Wofsy; Zhiming Kuang
Some Effects of Different Cloud Parameterizations in a Mesoscale Model and a Chemistry Transport Model
Chemistry transport models often ignore the cloud parameters that can be provided by meteorological pre-processors like mesoscale meteorological models. They often recalculate these parameters with algorithms that differ from those used in the ...
Nicole M�lders; Heinz Hass; Hermann J. Jakobs; Manfred Laube; Adolf Ebel
Can Fully Accounting for Clouds in Data Assimilation Improve Short-Term Forecasts by Global Models?
This paper explores the degree to which short-term forecasts with global models might be improved if clouds were fully included in a data assimilation system, so that observations of clouds affected all parts of the model state and cloud ...
Robert Pincus; Robert J. Patrick Hofmann; Jeffrey L. Anderson; Kevin Raeder; Nancy Collins; Jeffrey S. Whitaker
The Effects of Very Large Drops on Cloud Absorption. Part I: Parcel Models
In an effort to bring more realism cloud-radiation calculations, arising-parcel model of cloud microphysics and a 191 waveband model of atmospheric radiation (ATRAD) have been brought to bear on the problem of cloud absorption of solar radiation, ...
W. J. Wiscombe; R. M. Welch; W. D. Hall
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
Aerosol�Cloud Interactions in a Mesoscale Model. Part II: Sensitivity to Aqueous-Phase Chemistry
The feedbacks between aerosols, cloud microphysics, and cloud chemistry are investigated in a mesoscale model. A simple bulk aqueous-phase sulfur chemistry scheme was fully coupled to the existing aerosol and microphysics schemes. The ...
Irena T. Ivanova; Henry G. Leighton
Interactions between Cloud Microphysics and Cumulus Convection in a General Circulation Model
In the Colorado State University general circulation model, cumulus detrainment of cloud water and cloud ice has been, up to now, the only direct coupling between convective and large-scale condensation processes. This one-way interaction from ...
Laura D. Fowler; David A. Randall
Parameterization and Impact of Ice initiation Processes Relevant to Numerical Model Simulations of Cirrus Clouds
An effort to improve descriptions of ice initiation processes of relevance to cirrus clouds for use in regional-scale numerical cloud models with bulk microphysical schemes is described. This is approached by deriving practical parameterizations ...
Paul J. DeMott; Michael P. Meyers; William R. Cotton
Data Mining Numerical Model Output for Single-Station Cloud-Ceiling Forecast Algorithms
Accurate cloud-ceiling-height forecasts derived from numerical weather prediction (NWP) model data are useful for aviation and other interests where low cloud ceilings have an impact on operations. A demonstration of the usefulness of data-mining ...
Richard L. Bankert; Michael Hadjimichael
A Binned Approach to Cloud-Droplet Riming Implemented in a Bulk Microphysics Model
This paper presents the development and application of a binned approach to cloud-droplet riming within a bulk microphysics model. This approach provides a more realistic representation of collision�coalescence that occurs between ice and cloud ...
Stephen M. Saleeby; William R. Cotton
The Spurious Production of Cloud-Edge Supersaturations by Eulerian Models
The production of anomalous supersaturations at cloud edges other than cloud base has presented a vexing challenge for modelers attempting to represent the evolution of a droplet spectrum across an Eulerian grid. Although the problem manifests ...
Bjorn Stevens; Robert L. Walko; William R. Cotton; Graham Feingold
Specification of the Scale and Magnitude of Thermals Used to Initiate Convection in Cloud Models
Boundary layer similarity techniques are employed to specify the scale and intensity of a thermal perturbation used to initialize a cloud in a numerical cloud model. Techniques are outlined to specify the needed similarity variables from external ...
Richard T. McNider; Fred J. Kopp
Solar Activity and Cloud Opacity Variations: A Modulated Cosmic Ray Ionization Model
The observed correlation between global low cloud amount and the flux of high energy cosmic rays supports the idea that ionization plays a crucial role in tropospheric cloud formation. This idea is explored quantitatively with a simple model ...
David Marsden; Richard E. Lingenfelter
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
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
Modeling aerosol growth by aqueous chemistry in nonprecipitating stratiform cloud
A new microphysics module based on a two-dimensional (2D) joint size distribution function representing both interstitial and cloud particles is developed and applied to studying aerosol processing in non-precipitating stratocumulus clouds. The module is implemented in a three-dimensional dynamical framework of a large-eddy simulation (LES) model and in a trajectory ensemble model (TEM). Both models are used to study the modification of sulfate aerosol by the activation - aqueous chemistry - resuspension cycle in shallow marine stratocumulus clouds. The effect of particle mixing and different size-distribution representations on modeled aerosol processing are studied in a comparison of the LES and TEM simulations with the identical microphysics treatment exposes and a comparison of TEM simulations with a 2D fixed and moving bin microphysics. Particle mixing which is represented in LES and neglected in the TEM leads to the mean relative per particle dry mass change in the TEM simulations being about 30% lower than in analogous subsample of LES domain. Particles in the final LES spectrum are mixed in from different �parcels�, some of which have experienced longer in-cloud residence times than the TEM parcels, all of which originated in the subcloud layer, have. The mean relative per particle dry mass change differs by 14% between TEM simulations with fixed and moving bin microphysics. Finally, the TEM model with the moving bin microphysics is used to evaluate assumptions about liquid water mass partitioning among activated cloud condensation nuclei (CCN) of different dry sizes. These assumptions are used in large-scale models to map the bulk aqueous chemistry sulfate production, which is largely proportional to the liquid water mass, to the changes in aerosol size distribution. It is shown that the commonly used assumptions that the droplet mass is independent of CCN size or that the droplet mass is proportional to the CCN size to the third power do not perform well in the considered case. The explicitly predicted water partitioning indicates that the mean mass of droplets participating in the models aqueous chemistry calculations is proportional to the dry CCN size.
Ovchinnikov, Mikhail; Easter, Richard C.
Theory and Modeling of Fluids Group Homepage
... Modeling of Fluids Group is working in consort with the University of Colorado and the Division's Cryogenics Group on a DARPA funded project to ...
OF ENTRAINMENT IN THE OF ENTRAINMENT IN THE DIURNAL TRANSITION FROM SHALLOW TO DEEP CONVECTION Tony Del Genio and Jingbo Wu NASA/GISS ARM Science Team Meeting, 3/31/09 Continental rainfall rates tend to peak in mid-late afternoon or evening Time of peak rainfall, TRMM PR Hirose et al. (2008) But not in GCMs, which like to rain near noon ___ TRMM 3B42 - - - gauge colors = models IPCC AR4 models (Dai, 2006) Some recent studies * Derbyshire et al. (2004): SCMs insensitive to tropospheric humidity * Grabowski et al. (2006): Need entrainment rate to decrease with time of day * Kuang and Bretherton (2006): Weaker entrainment rates for deep than for shallow convection - increasing parcel size as cold pools form? * Khairoutdinov and Randall (2006): Demonstration of downdraft/cold pool role in transition from shallow to deep
An Investigation with a General Circulation Model of the Climatic Effects of Cloud Albedo Changes Caused by Atmospheric Pollution
A hemispheric general circulation model, with fixed zonally averaged cloud cover, was used to investigate the climatic impact of increased albedo of low-level clouds caused by atmospheric pollution. The albedo of these clouds was increased from ...
B. G. Hunt
The Simulation of a Convective Cloud in a 3D Model with Explicit Microphysics. Part II: Dynamical and Microphysical Aspects of Cloud Merger
The development and merger of pairs of convective clouds in a shear-free environment were simulated in an explicit microphysical cloud model. The occurrence or nonoccurrence of updraft merger and the timing of merger depended critically on the ...
Yefim L. Kogan; Alan Shapiro
Impact of Cloud-Nucleating Aerosols in Cloud-Resolving Model Simulations of Warm-Rain Precipitation in the East China Sea
Cloud-nucleating aerosols emitted from mainland China have the potential to influence cloud and precipitation systems that propagate through the region of the East China Sea. Both simulations from the Spectral Radiation-Transport Model for ...
Stephen M. Saleeby; Wesley Berg; Susan van den Heever; Tristan L�Ecuyer
Modeling of Stratocumulus Cloud Layers in a Large Eddy Simulation Model with Explicit Microphysics
A new large eddy simulation (LES) stratocumulus cloud model with an explicit formulation of micro-physical processes has been developed, and the results from three large eddy simulations are presented to illustrate the effects of the ...
Y. L. Kogan; M. P. Khairoutdinov; D. K. Lilly; Z. N. Kogan; Qingfu Liu
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
Model simulations of the first aerosol indirect effect and comparison of cloud susceptibility fo satellite measurements
Present-day global anthropogenic emissions contribute more than half of the mass in submicron particles primarily due to sulfate and carbonaceous aerosol components derived from fossil fuel combustion and biomass burning. These anthropogenic aerosols modify the microphysics of clouds by serving as cloud condensation nuclei (CCN) and enhance the reflectivity of low-level water clouds, leading to a cooling effect on climate (the Twomey effect or first indirect effect). The magnitude of the first aerosol indirect effect is associated with cloud frequency as well as a quantity representing the sensitivity of cloud albedo to changes in cloud drop number concentration. This quantity is referred to as cloud susceptibility [Twomey, 1991]. Analysis of satellite measurements demonstrates that marine stratus clouds are likely to be of higher susceptibility than continental clouds because of their lower number concentrations of cloud drops [Platnick and Twomey, 1994]. Here, we use an improved version of the fully coupled climate/chemistry model [Chuang et al., 1997] to calculate the global concentrations Of sulfate, dust, sea salt, and carbonaceous aerosols (biomass smoke and fossil fuel organic matter and black carbon). We investigated the impact of anthropogenic aerosols on cloud susceptibility and calculated the associated changes of shortwave radiative fluxes at the top of the atmosphere. We also examined the correspondence between the model simulation of cloud susceptibility and that inferred from satellite measurements to test whether our simulated aerosol concentrations and aerosol/cloud interactions give a faithful representation of these features.
Chuang, C; Penner, J E; Kawamoto, K
Liquid and Ice Cloud Microphysics in the CSU General Circulation Model. Part III: Sensitivity to Modeling Assumptions
The inclusion of cloud microphysical processes in general circulation models makes it possible to study the multiple interactions among clouds, the hydrological cycle, and radiation. The gaps between the temporal and spatial scales at which such ...
Use of a Lidar Forward Model for Global Comparisons of Cloud Fraction between the ICESat Lidar and the ECMWF Model
The performance of the European Centre for Medium-Range Weather Forecasts (ECMWF) model in simulating clouds is evaluated using observations by the Geoscience Laser Altimeter System lidar on the Ice, Cloud, and Land Elevation Satellite (ICESat). ...
Jonathan M. Wilkinson; Robin J. Hogan; Anthony J. Illingworth; Angela Benedetti
Climate-Weather Modeling Studies Using a Prototype Global Cloud-System
Climate-Weather Modeling Studies Using a Prototype Global Cloud-System Resolving Model Climate-Weather Modeling Studies Using a Prototype Global Cloud-System Resolving Model Climate-Weather Modeling Studies Using a Prototype Global Cloud-System Resolving Model PI Name: Venkatramani Balaji PI Email: email@example.com Institution: Geophysical Fluid Dynamics Laboratory Allocation Program: ESP Allocation Hours at ALCF: 150 Million Year: 2010 to 2013 Research Domain: Earth Science We expect our understanding of the role of clouds in climate to undergo a qualitative change as the resolutions of global models begin to encompass clouds. At these resolutions, non-hydrostatic dynamics become significant and deep convective processes are resolved. We are poised at the threshold of being able to run global scale simulations that include direct, non-parameterized, simulations of deep convective clouds. The goal of this
Cloud/Aerosol Parameterizations: Application and Improvement of General Circulation Models
One of the biggest uncertainties associated with climate models and climate forcing is the treatment of aerosols and their effects on clouds. The effect of aerosols on clouds can be divided into two components: The first indirect effect is the forcing associated with increases in droplet concentrations; the second indirect effect is the forcing associated with changes in liquid water path, cloud morphology, and cloud lifetime. Both are highly uncertain. This project applied a cloud-resolving model to understand the response of clouds under a variety of conditions to changes in aerosols. These responses are categorized according to the large-scale meteorological conditions that lead to the response. Meteorological conditions were sampled from various fields, which, together with a global aerosol model determination of the change in aerosols from present day to pre-industrial conditions, was used to determine a first order estimate of the response of global cloud fields to changes in aerosols. The response of the clouds in the NCAR CAM3 GCM coupled to our global aerosol model were tested by examining whether the response is similar to that of the cloud resolving model and methods for improving the representation of clouds and cloud/aerosol interactions were examined.
Penner, Joyce
Single Column Model Simulations of Cloud Sensitivity to Forcing
Single-Column Model Simulations Single-Column Model Simulations of Cloud Sensitivity to Forcing A. D. Del Genio National Aeronautics and Space Administration Goddard Institute for Space Studies New York, New York A. B. Wolf National Aeronautics and Space Administration SGT, Inc., Goddard Institute for Space Studies New York, New York Introduction The Atmospheric Radiation Measurement (ARM) Program single-column modeling (SCM) framework has to date used several fairly brief intensive observing periods (IOPs) to evaluate the performance of climate model parameterizations. With only a few weather events in each IOP, it is difficult to separate errors associated with the instantaneous dynamical forcing from errors in parameterization. It is also impossible to determine whether model errors are systematic and climatically significant. This
Validation of the Poisson Stochastic Radiative Transfer Model Against Cloud Cascade Models
Poisson Stochastic Radiative Transfer Poisson Stochastic Radiative Transfer Model Against Cloud Cascade Models T. B. Zhuravleva Institute of Atmospheric Optics Tomsk, Russia A. Marshak National Aeronautics and Space Administration Goddard Space Flight Center Greenbelt, Maryland Background Starting from a very simple stochastic cloud model by Mullamaa et al. (1972), several different stochastic models have been developed to describe radiative transfer regime in single-layer broken clouds (Kargin 1984; Titov 1990; Malvagi and Pomraning 1992; Barker et al. 1992; Malvagi et al. 1993; Kargin and Prigarin 1994; Prigarin and Titov 1996; Marshak et al. 1998; Prigarin et al. 1998, 2001; Evans et al. 1999, 2001). Recently Kassianov (2003a) generalized the Titov's (1990) stochastic model
A Novel MPPT Control Technology Based on Cloud Model for Photovoltaic Power Generation
The cloud model is a mathematical representation to fuzziness and randomness in linguistic concepts, and integrates the fuzziness and randomness of a linguistic concept in a unified way. This model is a new method for transformation between qualitative ... Keywords: photovoltaic power generation, MPPT, duty factor, cloud model
Lei An; Wei Fan
Parameterization of Heterogeneous Droplet Chemistry for Use in Bulk Cloud Models
Comparison of in-cloud sulfate production by a bulk-parameterized cloud model, a modified bulk parameterized model, and an explicit microphysical model for a wide variety of scenarios has been used as the basis for deriving a parameterization of ...
Po-Fat Yuen; Dean A. Hegg; Timothy V. Larson; Mary C. Barth
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.
Cloud computing adoption model for governments and large enterprises
Cloud Computing has held organizations across the globe spell bound with its promise. As it moves from being a buzz word and hype into adoption, organizations are faced with question of how to best adopt cloud. Existing ...
Trivedi, Hrishikesh
Resource allocation in cloud computing: model and algorithm
This paper provides an optimal approach to satisfy cloud user requests and schedule resources within cloud computing environment. The paper exploits the market concept into the interaction among the Software as a Service SaaS services providers, service ...
Chunlin Li; Layuan Li
Multiyear Evaluations of a Cloud Model Using ARM Data
This work uses long-term lidar and radar retrievals of the vertical structure of cloud at the Atmospheric Radiation Measurement (ARM) program�s Southern Great Plains site to evaluate cloud occurrence in multiyear runs of a cloud system�resolving ...
Peter W. Henderson; Robert Pincus
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
A Comparison of Three Different Modeling Strategies for Evaluating Cloud and Radiation Parameterizations
Parallel simulations of clouds and radiation fields by a single-column model (SCM), a regional circulation model, and a global circulation model (GCM), each using the same treatment of all physical processes and approximately the same spatial ...
Steven J. Ghan; L. Ruby Leung; James McCaa
New Primary Ice-Nucleation Parameterizations in an Explicit Cloud Model
Two new primary ice-nucleation parameterizations are examined in the Regional Atmospheric Modeling System (RAMS) cloud model via sensitivity tests on a wintertime precipitation event in the Sierra Nevada region. A model combining the effects of ...
Michael P. Meyers; Paul J. DeMott; William R. Cotton
An Earth Outgoing Longwave Radiation Climate Model. Part II: Radiation with Clouds Included
An Earth outgoing longwave radiation (OLWR) climate model was constructed for radiation budget studies. The model consists of the upward radiative transfer parameterization of Thompson and Warren, the cloud cover model of Sherr et al., and a ...
Shi-Keng Yang; G. Louis Smith; Fred L. Bartman
Validity of the Tangent Linear Approximation in a Moist Convective Cloud Model
The validity of the moist tangent linear model (TLM) derived from a time-dependent 1D Eulerian cloud model is investigated by comparing TLM solutions to differences between results from a nonlinear model identically perturbed. The TLM solutions ...
Seon Ki Park; Kelvin K. Droegemeier
Simulations of the Atmospheric General Circulation Using a Cloud-Resolving Model as a Superparameterization of Physical Processes
Traditionally, the effects of clouds in GCMs have been represented by semiempirical parameterizations. Recently, a cloud-resolving model (CRM) was embedded into each grid column of a realistic GCM, the NCAR Community Atmosphere Model (CAM), to ...
Marat Khairoutdinov; David Randall; Charlotte DeMott
Aerosol�Cloud Interactions in a Mesoscale Model. Part I: Sensitivity to Activation and Collision�Coalescence
High-resolution numerical simulations of the aerosol�cloud feedbacks are performed with a mesoscale model. The multimodal aerosol species, added to the model, and the cloud species were represented by two spectral moments. The aerosol sources ...
Fuzzy rule-based modeling of vapor cloud explosion probabilities
Estimating the frequency of accidents in nonreactor nuclear facilities is difficult because quantitative reliability data are lacking for many critical items. Because data are often lacking, the risk analysis relies on [open quotes]expert judgment[close quotes] or [open quotes]engineering judgment.[close quotes] This paper presents an alternative to the ad hoc use of engineering judgment in risk analysis. This alternative is fuzzy rule-based modeling. The fundamental principle of fuzzy rule-based modeling is that qualitative knowledge, which is the basis of engineering judgment, is valid knowledge. The intent of fuzzy rule-based modeling is to make better, systematic use of qualitative knowledge. The method is related to expert system technology. The basic concepts of fuzzy rule-based modeling, as applied to consequence modeling, have been discussed previously. This paper examines the application of these methods to the problem of estimating probabilities. The study considers a particular application, determining the probability of a deflagration-to-detonation transition in a vapor cloud.
Kubic, W.L. Jr. (Los Alamos National Lab., NM (United States))
We present an idealized, semi-empirical model for the evolution of gravitationally contracting molecular clouds (MCs) and their star formation rate (SFR) and efficiency (SFE). The model assumes that the instantaneous SFR is given by the mass above a certain density threshold divided by its free-fall time. The instantaneous number of massive stars is computed assuming a Kroupa initial mass function. These stars feed back on the cloud through ionizing radiation, eroding it. The main controlling parameter of the evolution turns out to be the maximum cloud mass, M{sub max}. This allows us to compare various properties of the model clouds against their observational counterparts. A giant molecular cloud (GMC) model (M{sub max} {approx} 10{sup 5} M{sub Sun }) adheres very well to the evolutionary scenario recently inferred by Kawamura et al. for GMCs in the Large Magellanic Cloud. A model cloud with M{sub max} Almost-Equal-To 2000 M{sub Sun} evolves in the Kennicutt-Schmidt diagram, first passing through the locus of typical low-to-intermediate-mass star-forming clouds, and then moving toward the locus of high-mass star-forming ones over the course of {approx}10 Myr. Also, the stellar age histograms for this cloud a few Myr before its destruction agree very well with those observed in the {rho}-Oph stellar association, whose parent cloud has a similar mass, and imply that the SFR of the clouds increases with time. Our model thus agrees well with various observed properties of star-forming MCs, suggesting that the scenario of gravitationally collapsing MCs, with their SFR regulated by stellar feedback, is entirely feasible and in agreement with key observed properties of MCs.
Zamora-Aviles, Manuel; Vazquez-Semadeni, Enrique; Colin, Pedro [Centro de Radioastronomia y Astrofisica, Universidad Nacional Autonoma de Mexico, Apdo. Postal 3-72, Morelia, Michoacan, 58089 (Mexico)
Combining Cloud-Resolving Model with Satellite for Cloud Process Model Simulation Validation
Advances in computer power have made it possible to increase the spatial resolution of regional numerical models to a scale encompassing larger convective elements of less than 5 km in size. One goal of high resolution is to begin to resolve ...
Renato G. Negri; Luiz A. T. Machado; Stephen English; Mary Forsythe
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,...
Model Rain and Clouds over Oceans: Comparison with SSM/I Observations
A comparison of global model cloud and rain parameterization output with satellite observed radiances was carried out. Hydrometeor profiles from ECMWF operational short-range forecasts were combined with a microwave radiative transfer model to ...
Fr�d�ric Chevallier; Peter Bauer
The Impact of Spectral Nudging on Cloud Simulation with a Regional Atmospheric Model
The impact of spectral nudging on cloud simulation with a regional atmospheric model was examined. Simulated cloudiness of the Regional Model (REMO) and the Spectrally Nudged REMO (SN-REMO) were intercompared and evaluated with satellite-derived ...
Insa Meinke; Beate Geyer; Frauke Feser; Hans von Storch
An Improved Parameterization for Simulating Arctic Cloud Amount in the CCSM3 Climate Model
A simple alternative parameterization for predicting cloud fraction in the Community Climate System Model, version 3 (CCSM3) global climate model is presented. This formula, dubbed �freeezedry,� is designed to alleviate the bias of excessive low ...
Steve Vavrus; Duane Waliser
The Application of Time Series Models to Cloud Field Morphology Analysis
A modeling method for the quantitative description of remotely sensed cloud field images is presented. A two-dimensional texture modeling scheme based on one-dimensional time series procedures is adopted for this purpose. The time series ...
Roland T. Chin; Jack Y. C. Jau; James A. Weinman
Effect of Cloud-Radiation Feedback on the Climate of a General Circulation Model
The General Circulation Model (GCM) of the Goddard Laboratory for Atmospheric Sciences (GLAS) was integrated for 107 days starting from the initial conditions of 15 May. In this experiment the clouds dynamically generated by the model affect the ...
J. Shukla; Y. Sud
Microwave Simulations of a Tropical Rainfall System with a Three-Dimensional Cloud Model
A three-dimensional cloud model-microwave radiative transfer model combination is used to study the relations among the precipitation and other microphysical characteristics of a tropical oceanic squall line and the upwelling radiance at ...
Robert F. Adler; Hwa-Young M. Yeh; N. Prasad; Wei-Kuo Tao; Joanne Simpson
Large-Scale Atmospheric Forcing by Southeast Pacific Boundary Layer Clouds: A Regional Model Study
A regional model is used to study the radiative effect of boundary layer clouds over the southeast Pacific on large-scale atmosphere circulation during August�October 1999. With the standard settings, the model simulates reasonably well the large-...
Yuqing Wang; Shang-Ping Xie; Bin Wang; Haiming Xu
Reproducibility by Climate Models of Cloud Radiative Forcing Associated with Tropical Convection
In this study, cloud radiative forcing (CRF) associated with convective activity over tropical oceans is analyzed for monthly mean data from twentieth-century simulations of 18 climate models participating in phase 3 of the Coupled Model ...
Hiroki Ichikawa; Hirohiko Masunaga; Yoko Tsushima; Hiroshi Kanzawa
Cloud and Water Vapor Feedbacks in a Vertical Energy-Balance Model with Maximum Entropy Production
A vertically one-dimensional model is developed with cloud fraction constrained by the maximum entropy production (MEP) principle. The model reasonably reproduces the global mean climate with its surface temperature, radiation and heat fluxes, ...
Biao Wang; Teruyuki Nakajima; Guangyu Shi
Prediction of Clouds and Rain Using a z-Coordinate Nonhydrostatic Model
The most common option for numerical models of the atmosphere is to use model layers following the surface of the earth, using a terrain-following vertical coordinate. The present paper investigates the forecast of clouds and precipitation using ...
J. Steppeler; H. W. Bitzer; Z. Janjic; U. Sch�ttler; P. Prohl; U. Gjertsen; L. Torrisi; J. Parfinievicz; E. Avgoustoglou; U. Damrath
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
Evaluation of Cloud-Resolving Model Intercomparison Simulations Using TWP-ICE Observations: Precipitation and Cloud Structure
The Tropical Warm Pool � International Cloud Experiment (TWP-ICE) provided high quality model forcing and observational datasets through which detailed model and observational intercomparisons could be performed. In this first of a two part study, precipitation and cloud structures within nine cloud-resolving model simulations are compared with scanning radar reflectivity and satellite infrared brightness temperature observations during an active monsoon period from 19 to 25 January 2006. Most simulations slightly overestimate volumetric convective rainfall. Overestimation of simulated convective area by 50% or more in several simulations is somewhat offset by underestimation of mean convective rain rates. Stratiform volumetric rainfall is underestimated by 13% to 53% despite overestimation of stratiform area by up to 65% because stratiform rain rates in every simulation are much lower than observed. Although simulations match the peaked convective radar reflectivity distribution at low levels, they do not reproduce the peaked distributions observed above the melting level. Simulated radar reflectivity aloft in convective regions is too high in most simulations. In stratiform regions, there is a large spread in model results with none resembling observed distributions. Above the melting level, observed radar reflectivity decreases more gradually with height than simulated radar reflectivity. A few simulations produce unrealistically uniform and cold 10.8-?m infrared brightness temperatures, but several simulations produce distributions close to observed. Assumed ice particle size distributions appear to play a larger role than ice water contents in producing incorrect simulated radar reflectivity distributions aloft despite substantial differences in mean graupel and snow water contents across models.
Varble, Adam; Fridlind, Ann; Zipser, Edward J.; Ackerman, Andrew; Chaboureau, Jean-Pierre; Fan, Jiwen; Hill, Adrian; McFarlane, Sally A.; Pinty, Jean-Pierre; Shipway, Ben
The Venusian Y-Shaped Cloud Pattern Based on an Aerosol-Transport Model
Venusian Y-shaped clouds have been observed by ultraviolet (UV) detectors. Recently, it has been demonstrated that the Y-shaped cloud pattern is maintained by the dynamical combination of an equatorial 4-day wave and a Rossby wave. In the model ...
Masaru Yamamoto; Hiroshi Tanaka
Representation of Boundary Layer Moisture Transport in Cloud-Resolving Models
One of the important roles of the PBL is to transport moisture from the surface to the cloud layer. However, how this transport process can be accounted for in cloud-resolving models (CRMs) is not sufficiently clear and has rarely been examined. A ...
Chin-Hoh Moeng; Akio Arakawa
Execution of a Global Cloud Resolving Model (GCRM) at target resolutions of 2-4 km will generate, at a minimum, 10s of Gigabytes of data per variable per snapshot. Writing this data to disk without creating a serious bottleneck in the execution of the GCRM code while also supporting efficient post-execution data analysis is a significant challenge. This paper discusses an Input/Output (IO) application programmer interface (API) for the GCRM that efficiently moves data from the model to disk while maintaining support for community standard formats, avoiding the creation of very large numbers of files, and supporting efficient analysis. Several aspects of the API will be discussed in detail. First, we discuss the output data layout which linearizes the data in a consistent way that is independent of the number of processors used to run the simulation and provides a convenient format for subsequent analyses of the data. Second, we discuss the flexible API interface that enables modelers to easily add variables to the output stream by specifying where in the GCRM code these variables are located and to flexibly configure the choice of outputs and distribution of data across files. The flexibility of the API is designed to allow model developers to add new data fields to the output as the model develops and new physics is added and also provides a mechanism for allowing users of the GCRM code itself to adjust the output frequency and the number of fields written depending on the needs of individual calculations. Third, we describe the mapping to the NetCDF data model with an emphasis on the grid description. Fourth, we describe our messaging algorithms and IO aggregation strategies that are used to achieve high bandwidth while simultaneously writing concurrently from many processors to shared files. We conclude with initial performance results.
Palmer, Bruce J.; Koontz, Annette S.; Schuchardt, Karen L.; Heikes, Ross P.; Randall, David A.
Two-component model of the interaction of an interstellar cloud with surrounding hot plasma
We present a two-component gasdynamic model of an interstellar cloud embedded in a hot plasma. It is assumed that the cloud consists of atomic hydrogen gas, interstellar plasma is quasineutral. Hydrogen atoms and plasma protons interact through a charge exchange process. Magnetic felds and radiative processes are ignored in the model. The influence of heat conduction within plasma on the interaction between a cloud and plasma is studied. We consider the extreme case and assume that hot plasma electrons instantly heat the plasma in the interaction region and that plasma flow can be described as isothermal. Using the two-component model of the interaction of cold neutral cloud and hot plasma, we estimate the lifetime of interstellar clouds. We focus on the clouds typical for the cluster of local interstellar clouds embedded in the hot Local Bubble and give an estimate of the lifetime of the Local interstellar cloud where the Sun currently travels. The charge transfer between highly charged plasma ions and neutr...
Provornikova, E A; Lallement, R
Ground-based Microwave Cloud Tomography
Microwave Cloud Tomography Microwave Cloud Tomography Experiment, SGP, May 15-June 15, 2009 Lead Scientist Dong Huang, BNL Co-Investigators Al Gasiewski, UC Boulder Maria Cadeddu, ANL Warren Wiscombe, BNL Radiation Processes Working Group March 30, 2009 multiple radiometers All good cloud radiation modelers should close their airplane window shades so as not to be corrupted by the spectacle of real 3D clouds. - Roger Davies In case you forget to do this, you see 3/30/2009 ARM RPWG 2 Effects of cloud structure on radiation 3/30/2009 ARM RPWG 3 Typical climate model - Cloud fraction & mean water content - Horizontally uniform clouds, no side radiation - Assumption on overlap Courtesy of Bernhard Mayer Cloud structure important to radiation - Cumulus (Benner & Evans 2001, Pincus et al. 2005), deep convection (DiGiuseppe &
Initialization of a Cloud-Resolving Model with Airborne Doppler Radar Observations of an Oceanic Tropical Convective System
Doppler radar�derived fields of wind and reflectivity, retrieved temperature perturbations, estimated water vapor, and cloud water contents are used to initialize a nonhydrostatic cloud-resolving model. Airborne Doppler data collected in a ...
Soline Bielli; Frank Roux
Assessing a Cloud Optical Depth Retrieval Algorithm with Model-Generated Data and the Frozen Turbulence Assumption
A cloud optical depth retrieval algorithm that utilizes time series of solar irradiance and zenith downwelling radiance data collected at a fixed surface site is assessed using model-generated cloud fields and simulated radiation measurements. To ...
H. W. Barker; C. F. Pavloski; M. Ovtchinnikov; E. E. Clothiaux
Nucleation Processes in Deep Convection Simulated by a Cloud-System-Resolving Model with Double-Moment Bulk Microphysics
A novel type of limited double-moment scheme for bulk microphysics is presented here for cloud-system-resolving models (CSRMs). It predicts the average size of cloud droplets and crystals, which is important for representing the radiative impact ...
Vaughan T. J. Philips; Leo J. Donner; Stephen T. Garner
The Effects of Evaporation, Water Load and Wind Shear on Cloud Development in a Three-Dimensional Numerical Model
Steiner's (1973) three-dimensional cloud model has been updated to incorporate the deep anelastic system of equations and the microphysical parameterization scheme of Kessler (1969) for precipitation growth. The interactions between cloud ...
Man Kong Yau
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
Assimilation of MODIS Cloud Optical Depths in the ECMWF Model
At the European Centre for Medium-Range Weather Forecasts (ECMWF), a large effort has recently been devoted to define and implement moist physics schemes for variational assimilation of rain- and cloud-affected brightness temperatures. This study ...
Angela Benedetti; Marta Janiskov�
A Stochastic Mixing Model for Nonprecipitating Cumulus Clouds
Recent work suggests that nonprecipitating cumulus clouds must be considered as aggregates of many parcels always moving toward buoyancy equilibrium, but otherwise subject to a multiplicity of fates. For example, some parcels originating at low ...
David J. Raymond; Alan M. Blyth
The Simulation of a Convective Cloud in a 3-D Model With Explicit Microphysics. Part I: Model Description and Sensitivity Experiments
A three-dimensional nonhydrostatic anelastic numerical model of a convective cloud with an explicit description of microphysical processes has been developed. Two distribution functions are considered in the model�one for cloud condensation ...
Yefim L. Kogan
Integrated model shows that atmospheric brown clouds and greenhouse gases have reduced rice harvests in India
Previous studies have found that atmospheric brown clouds partially offset the warming effects of greenhouse gases. This finding suggests a tradeoff between the impacts of reducing emissions of aerosols and greenhouse gases. Results from a statistical model of historical rice harvests in India, coupled with regional climate scenarios from a parallel climate model, indicate that joint reductions in brown clouds and greenhouse gases would in fact have complementary, positive impacts on harvests. The results also imply that adverse climate change due to brown clouds and greenhouse gases contributed to the slowdown in harvest growth that occurred during the past two decades.
Auffhammer, M. [Univ. of California, Berkeley, CA (United States). Dept. of Agricultural and Resource Economics; Ramanathan, V. [Scripps Institution of Oceanography, San Diego, CA (United States); Vincent, J.R. [Univ. of California, San Diego, CA (United States). Graduate School of International Relations and Pacific Studies
Three-Dimensional Linear Instability Modeling of the Cloud Level Venus Atmosphere
Based on the success of several 2-D (latitude, longitude) linear barotropic instability models at matching some of the observed characteristics of the cloud level, polar region of the Venus atmosphere, a more realistic, linear, 3-D (height, ...
Lee S. Elson
Environment and the Lifetime of Tropical Deep Convection in a Cloud-Permitting Regional Model Simulation
By applying a cloud tracking algorithm to tropical convective systems in a simulated a regional high resolution model simulation, this study documents the environmental conditions before and after convective systems are initiated over ocean and ...
Samson Hagos; Zhe Feng; Sally McFarlane; L. Ruby Leung
STORMTIPE: A Forecasting Experiment Using a Three-Dimensional Cloud Model
An experiment using a three-dimensional cloud-scale numerical model in an operational forecasting environment was carried out in the spring of 1991. It involved meteorologists generating forecast environmental conditions associated with ...
Harold E. Brooks; Charles A. Doswell III; Louis J. Wicker
Cloud Simulations in Response to Turbulence Parameterizations in the GISS Model E GCM
The response of cloud simulations to turbulence parameterizations is studied systematically using the GISS general circulation model (GCM) E2 employed in the Intergovernmental Panel on Climate Change�s (IPCC) Fifth Assessment Report (AR5). Without ...
Mao-Sung Yao; Ye Cheng
A Clustering Approach to Compare Cloud Model Simulations to Satellite Observations
Cloud-resolving models (CRMs) offer an important pathway to interpret satellite observations of microphysical properties of storms. High-frequency microwave brightness temperatures (Tbs) respond to precipitating-sized ice particles and can ...
Fang Wang; Christian Kummerow
The Effects of Subgrid Model Mixing and Numerical Filtering in Simulations of Mesoscale Cloud Systems
Using the newly developed Weather Research and Forecasting (WRF) model, this study investigates the effects of subgrid mixing and numerical filtering in mesoscale cloud simulations by examining the sensitivities to the parameters in turbulence-...
Tetsuya Takemi; Richard Rotunno
Evaluating Mesoscale Model Predictions of Clouds and Radiation with SGP ARM Data over a Seasonal Timescale
This study evaluates the predictions of radiative and cloud-related processes of the fifth-generation Pennsylvania State University�National Center for Atmospheric Research (PSU�NCAR) Mesoscale Model (MM5). It is based on extensive comparison of ...
Fran�oise Guichard; David B. Parsons; Jimy Dudhia; James Bresch
An Explicit One-Dimensional Time-Dependent Tilting Cloud Model
An explicit one-dimensional time-dependent tilting cloud model has been developed for use in cumulus parameterizations. The tilting axis is not necessarily orthogonal to the (r, ?) plane, making the horizontal axisymmetric assumption more ...
Shu-Hua Chen; Wen-Yih Sun
Impact of Ingesting Satellite-Derived Cloud Cover into the Regional Atmospheric Modeling System
This study investigates the extent to which assimilating high-resolution remotely sensed cloud cover into the Regional Atmospheric Modeling System (RAMS) provides an improved regional diagnosis of downward short- and longwave surface radiation ...
Ismail Yucel; W. James Shuttleworth; R. T. Pinker; L. Lu; S. Sorooshian
On the Use of Mesoscale and Cloud-Scale Models in Operational Forecasting
In the near future, the technological capability will be available to use mesoscale and cloud-scale numerical models for forecasting convective weather in operational meteorology. We address some of the issues concerning effective utilization of ...
Harold E. Brooks; Charles A. Doswell III; Robert A. Maddox
Diabatic Forcing and Initialization with Assimilation of Cloud Water and Rainwater in a Forecast Model
In this study, diabatic initialization, diabatic forcing, and liquid water assimilation techniques are tested in a semi-implicit hydrostatic regional forecast model containing explicit representations of grid-scale cloud water and rainwater. ...
William H. Raymond; William S. Olson; Geary Callan
Convective Forcing Fluctuations in a Cloud-Resolving Model: Relevance to the Stochastic Parameterization Problem
Idealized cloud-resolving model (CRM) simulations spanning a large part of the tropical atmosphere are used to evaluate the extent to which deterministic convective parameterizations fail to capture the statistical fluctuations in deep-convective ...
G. J. Shutts; T. N. Palmer
Effects of Cumulus Entrainment and Multiple Cloud Types on a January Global Climate Model Simulation
An improved version of the GISS Model II cumulus parameterization designed for long-term climate integrations is used to study the effects of entrainment and multiple cloud types on the January climate simulation. Instead of prescribing ...
Mao-Sung Yao; Anthony D. Del Genio
Another Look at Stochastic Condensation for Subgrid Cloud Modeling: Adiabatic Evolution and Effects
The theory of stochastic condensation, which models the impact of an ensemble of unresolved supersaturation fluctuations S? on the volume-averaged droplet-size distribution f?(r), is revisited in the modern context of subgrid cloud ...
Christopher A. Jeffery; Jon M. Reisner; Miroslaw Andrejczuk
Comparisons between Model Forecast and Observed Boundary Layer Profiles and Related Comments on Cloud Prediction
In this study comparisons are made between Met Office mesoscale model boundary layer profiles, and radiosonde data collected in the central United Kingdom during three intensive boundary layer cloud experiments. Significant differences between ...
J. D. Price; M. R. Bush
By applying a cloud-tracking algorithm to tropical convective systems in a regional high-resolution model simulation, this study documents the environmental conditions before and after convective systems are initiated over ocean and land by ...
Observed Scaling in Clouds and Precipitation and Scale Incognizance in Regional to Global Atmospheric Models
We use observations of robust scaling behavior in clouds and precipitation to derive constraints on how partitioning of precipitation should change with model resolution. Our analysis indicates that 90�99% of stratiform precipitation should occur ...
Travis A. O�Brien; Fuyu Li; William D. Collins; Sara A. Rauscher; Todd D. Ringler; Mark Taylor; Samson M. Hagos; L. Ruby Leung
Numerical Simulations of Observed Arctic Stratus Clouds Using a Second-Order Turbulence Closure Model
A high-resolution one-dimensional version of a second-order turbulence closure radiative-convective model, developed at Los Alamos National Laboratory, is used to simulate the interactions among turbulence, radiation, and bulk cloud parameters in ...
W. S. Smith; C-Y. J. Kao
Hierarchical Tropical Cloud Systems in an Analog Shallow-Water Model
Recent observations have revealed an hierarchy of cloud clusters and superclusters within the Madden-Julian oscillation of the equatorial troposphere. The authors here report on the results of simulations with a model based on a simple nonlinear ...
Jun-Ichi Yano; James C. McWilliams; Mitchell W. Moncrieff; Kerry A. Emanuel
Unified Treatment of Thermodynamic and Optical Variability in a Simple Model of Unresolved Low Clouds
Comparative studies of global climate models have long shown a marked sensitivity to the parameterization of cloud properties. Early attempts to quantify this sensitivity were hampered by diagnostic schemes that were inherently biased toward the ...
Christopher A. Jeffery; Philip H. Austin
PBL Stratiform Cloud Inhomogeneities Thermally Induced by the Orography: A Parameterization for Climate Models
This paper proposes a parameterization for use in climate models of the orographic variance and associated thermal circulation's impact on the macroscopic behavior of planetary boundary layer (PBL) stratiform clouds. Orographically induced ...
Rafael Terra
A Cumulus Parameterization Based on a Cloud Model of Intermittently Rising Thermals
The author presents a cumulus parameterization that uses a cloud model that describes atmospheric convection as consisting of a sequence of intermittently rising thermals. The total mass of thermals in a convection event is determined by the ...
Qi Hu
Simulation of Coastal Circulation in the Eastern Mediterranean Using a Spectral Microphysics Cloud Ensemble Model
The interaction of the cold season land breeze with the background flow in the Eastern Mediterranean and its influence on the climatic distribution of convective precipitation is studied using a 2D nonhydrostatic cloud ensemble model with the ...
Alexander P. Khain; Igor Sednev; V. Khvorostyanov
Initial Tendencies of Cloud Regimes in the Met Office Unified Model
The Met Office unified forecast�climate model is used to compare the properties of simulated climatological cloud regimes with those produced in short-range forecasts initialized from operational analyses. The regimes are defined as principal ...
K. D. Williams; M. E. Brooks
A Simple Parameterization of Cloud Water Related Variables for Use in Boundary Layer Models
A simple parameterization of cloud water related variables has been developed which can be used in meteorological models that use a prognostic equation for the turbulent kinetic energy. Based on the results of large-eddy simulations (LES), ...
J. W. M. Cuijpers; P. Bechtold
Assessing 1D Atmospheric Solar Radiative Transfer Models: Interpretation and Handling of Unresolved Clouds
The primary purpose of this study is to assess the performance of 1D solar radiative transfer codes that are used currently both for research and in weather and climate models. Emphasis is on interpretation and handling of unresolved clouds. ...
H. W. Barker; G. L. Stephens; P. T. Partain; J. W. Bergman; B. Bonnel; K. Campana; E. E. Clothiaux; S. Clough; S. Cusack; J. Delamere; J. Edwards; K. F. Evans; Y. Fouquart; S. Freidenreich; V. Galin; Y. Hou; S. Kato; J. Li; E. Mlawer; J.-J. Morcrette; W. O'Hirok; P. R�is�nen; V. Ramaswamy; B. Ritter; E. Rozanov; M. Schlesinger; K. Shibata; P. Sporyshev; Z. Sun; M. Wendisch; N. Wood; F. Yang
Spacelike Ricci Inheritance Vectors in a Model of String Cloud and String Fluid Stress Tensor
We study the consequences of the existence of spacelike Ricci inheritance vectors (SpRIVs) parallel to $x^a$ for model of string cloud and string fluid stress tensor in the context of general relativity. Necessary and sufficient conditions are derived for a spacetime with a model of string cloud and string fluid stress tensor to admit a SpRIV and a SpRIV which is also a spacelike conformal Killing vector (SpCKV). Also, some results are obtained.
H. Baysal; I. Yilmaz
Model analysis of the anthropogenic aerosol effect on clouds over East Asia
A coupled meteorology and aerosol/chemistry model WRF-Chem (Weather Research and Forecast model coupled with Chemistry) was used to conduct a pair of simulations with present-day (PD) and preindustrial (PI) emissions over East Asia to examine the aerosol indirect effect on clouds. As a result of an increase in aerosols in January, the cloud droplet number increased by 650 cm{sup -3} over the ocean and East China, 400 cm{sup -3} over Central and Southwest China, and less than 200 cm{sup -3} over North China. The cloud liquid water path (LWP) increased by 40-60 g m{sup -2} over the ocean and Southeast China and 30 g m{sup -2} over Central China; the LWP increased less than 5 g m{sup -2} or decreased by 5 g m{sup -2} over North China. The effective radius (Re) decreased by more than 4 {mu}m over Southwest, Central, and Southeast China and 2 {mu}m over North China. In July, variations in cloud properties were more uniform; the cloud droplet number increased by approximately 250-400 cm{sup -3}, the LWP increased by approximately 30-50 g m{sup -2}, and Re decreased by approximately 3 {mu}m over most regions of China. In response to cloud property changes from PI to PD, shortwave (SW) cloud radiative forcing strengthened by 30 W m{sup -2} over the ocean and 10 W m{sup -2} over Southeast China, and it weakened slightly by approximately 2-10 W m{sup -2} over Central and Southwest China in January. In July, SW cloud radiative forcing strengthened by 15 W m{sup -2} over Southeast and North China and weakened by 10 W m{sup -2} over Central China. The different responses of SW cloud radiative forcing in different regions was related to cloud feedbacks and natural variability.
Gao, Yi; Zhang, Meigen; Liu, Xiaohong; Zhao, Chun
The Tropical Warm Pool - International Cloud Experiment (TWP-ICE) provided high quality model forcing and observational datasets through which detailed model and observational intercomparisons could be performed. In this first of a two part study, precipitation and cloud structures within nine cloud-resolving model simulations are compared with scanning radar reflectivity and satellite infrared brightness temperature observations during an active monsoon period from 19 to 25 January 2006. Most simulations slightly overestimate volumetric convective rainfall. Overestimation of simulated convective area by 50% or more in several simulations is somewhat offset by underestimation of mean convective rain rates. Stratiform volumetric rainfall is underestimated by 13% to 53% despite overestimation of stratiform area by up to 65% because stratiform rain rates in every simulation are much lower than observed. Although simulations match the peaked convective radar reflectivity distribution at low levels, they do not reproduce the peaked distributions observed above the melting level. Simulated radar reflectivity aloft in convective regions is too high in most simulations. 29 In stratiform regions, there is a large spread in model results with none resembling 30 observed distributions. Above the melting level, observed radar reflectivity decreases 31 more gradually with height than simulated radar reflectivity. A few simulations produce 32 unrealistically uniform and cold 10.8-?m infrared brightness temperatures, but several 33 simulations produce distributions close to observed. Assumed ice particle size 34 distributions appear to play a larger role than ice water contents in producing incorrect 35 simulated radar reflectivity distributions aloft despite substantial differences in mean 36 graupel and snow water contents across models. 37
Varble, Adam C.; Fridlind, Ann; Zipser, Ed; Ackerman, Andrew; Chaboureau, Jean-Pierre; Fan, Jiwen; Hill, Adrian; McFarlane, Sally A.; Pinty, Jean-Pierre; Shipway, Ben
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
Soot microphysical effects on liquid clouds, a multi-model investigation
Soot microphysical effects on liquid clouds, a multi-model investigation Soot microphysical effects on liquid clouds, a multi-model investigation Title Soot microphysical effects on liquid clouds, a multi-model investigation Publication Type Journal Article Year of Publication 2011 Authors Koch, Dorothy M., Yves Balkanski, Susanne E. Bauer, Richard C. Easter, Sylvaine Ferrachat, Steven J. Ghan, Corinna Hoose, Trond Iversen, Alf Kirkevåg, Jon E. Kristjánsson, Xiaohong Liu, Ulrike Lohmann, Surabi Menon, Johannes Quaas, Michael Schulz, Øyvind Seland, Toshihiko Takemura, and N. Yan Journal Atmospheric Chemistry and Physics Volume 11 Pagination 1051-1064 Abstract We use global models to explore the microphysical effects of carbonaceous aerosols on liquid clouds. Although absorption of solar radiation by soot warms the atmosphere, soot may cause climate cooling due to its contribution to cloud condensation nuclei (CCN) and therefore cloud brightness. Six global models conducted three soot experiments; four of the models had detailed aerosol microphysical schemes. The average cloud radiative response to biofuel soot (black and organic carbon), including both indirect and semi-direct effects, is -0.11 Wm-2, comparable in size but opposite in sign to the respective direct effect. In a more idealized fossil fuel black carbon experiment, some models calculated a positive cloud response because soot provides a deposition sink for sulfuric and nitric acids and secondary organics, decreasing nucleation and evolution of viable CCN. Biofuel soot particles were also typically assumed to be larger and more hygroscopic than for fossil fuel soot and therefore caused more negative forcing, as also found in previous studies. Diesel soot (black and organic carbon) experiments had relatively smaller cloud impacts with five of the models <±0.06 Wm-2 from clouds. The results are subject to the caveats that variability among models, and regional and interrannual variability for each model, are large. This comparison together with previously published results stresses the need to further constrain aerosol microphysical schemes. The non-linearities resulting from the competition of opposing effects on the CCN population make it difficult to extrapolate from idealized experiments to likely impacts of realistic potential emission changes.
Characteristics of Correlation Statistics between Droplet Radius and Optical Thickness of Warm Clouds Simulated by a Three-Dimensional Regional-Scale Spectral Bin Microphysics Cloud Model
Three-dimensional downscaling simulations using a spectral bin microphysics (SBM) model were conducted to investigate the effects of aerosol amount and dynamical stabilities of the atmosphere on the correlation statistics between cloud droplet ...
Yousuke Sato; Kentaroh Suzuki; Takamichi Iguchi; In-Jin Choi; Hiroyuki Kadowaki; Teruyuki Nakajima
Ensemble Simulation of the Lightning Flash Variability in a 3D Cloud Model with Parameterizations of Cloud Electrification and Lightning Flashes
A series of ensemble simulations were performed to study the statistics of flash characteristics produced by an electrification and lightning scheme in the cloud-resolving model M�so-NH. Here, the electrical variability of two storms�one ...
Jean-Pierre Pinty; Christelle Barthe
An Investigation of Ice Production Mechanisms in Small Cumuliform Clouds Using a 3D Model with Explicit Microphysics. Part II: Case Study of New Mexico Cumulus Clouds
A new 3D model with explicit liquid- and ice-phase microphysics and a detailed treatment of ice nucleation and multiplication processes is applied to study ice formation and evolution in cumulus clouds. Simulation results are compared with in ...
Mikhail Ovtchinnikov; Yefim L. Kogan; Alan M. Blyth
Comparison of the Vertical Velocity Used to Calculate the Cloud Droplet Number Concentration in a Cloud Resolving and a Global Climate Model
Comparison of the Vertical Velocity Comparison of the Vertical Velocity used to Calculate the Cloud Droplet Number Concentration in a Cloud-Resolving and a Global Climate Model H. Guo, J. E. Penner, M. Herzog, and X. Liu Department of Atmospheric, Oceanic and Space Sciences University of Michigan Ann Arbor, Michigan Introduction Anthropogenic aerosols are effective cloud condensation nuclei (CCN). The availability of CCN affects the initial cloud droplet number concentration (CDNC) and droplet size; therefore, cloud optical properties (the so-called first aerosol indirect effect). However, the estimate of CDNC from a mechanistic treatment shows significant differences from the empirical schemes mainly due to the large bias of the large-scale vertical velocity (w) (Ghan et al. 1993, 1995; Boucher and Lohmann 1995;
Evaluating Low-Cloud Simulation from an Upgraded Multiscale Modeling Framework Model. Part II: Seasonal Variations over the Eastern Pacific
The eastern Pacific is a climatologically important region. Conventional coupled atmosphere�ocean general circulation models produce positive sea surface temperature biases of 2�5 K in this region because of insufficient stratocumulus clouds. In ...
Kuan-Man Xu; Anning Cheng
Liquid and Ice Cloud Microphysics in the CSU General Circulation Model. Part 1: Model Description and Simulated Microphysical Processes
Microphysical processes responsible for the formation and dissipation of water and ice clouds have been incorporated into the Colorado State University General Circulation Model in order to 1) yield a more physically based representation of the ...
Laura D. Fowler; David A. Randall; Steven A. Rutledge
Modeling the Interaction between Cumulus Convection and Linear Gravity Waves Using a Limited-Domain Cloud System�Resolving Model
A limited-domain cloud system�resolving model (CSRM) is used to simulate the interaction between cumulus convection and two-dimensional linear gravity waves, a single horizontal wavenumber at a time. With a single horizontal wavenumber, soundings ...
Zhiming Kuang
Rain Production in Convective Clouds As Simulated in an Axisymmetric Model with Detailed Microphysics. Part I: Description of the Model
A hydrodynamic nonhydrostatic anelastic numerical model of an axisymmetric convective cloud is described in which the microphysical processes are treated in detail for different species of hydrometeors: drops. ice crystals, graupel, and snow ...
Tamir Reisin; Zev Levin; Shalva Tzivion
Interpretation of Multiwavelength-Retrieved Droplet Effective Radii for Warm Water Clouds in Terms of In-Cloud Vertical Inhomogeneity by Using a Spectral Bin Microphysics Cloud Model
This study examines the impact of in-cloud vertical inhomogeneity on cloud droplet effective radii (CDERs) of water-phase cloud retrieved from 1.6-, 2.1-, and 3.7-?m-band measurements (denoted by r1.6, r2.1, and r3.7, respectively). Discrepancies ...
Takashi M. Nagao; Kentaroh Suzuki; Takashi Y. Nakajima
Development and Testing of a Life Cycle Model and a Parameterization of Thin Mid-level Stratiform Clouds
We used a cloud-resolving model (a detailed computer model of cloud systems) to evaluate and improve the representation of clouds in global atmospheric models used for numerical weather prediction and climate modeling. We also used observations of the atmospheric state, including clouds, made at DOE's Atmospheric Radiation Measurement (ARM) Program's Climate Research Facility located in the Southern Great Plains (Kansas and Oklahoma) during Intensive Observation Periods to evaluate our detailed computer model as well as a single-column version of a global atmospheric model used for numerical weather prediction (the Global Forecast System of the NOAA National Centers for Environmental Prediction). This so-called Single-Column Modeling approach has proved to be a very effective method for testing the representation of clouds in global atmospheric models. The method relies on detailed observations of the atmospheric state, including clouds, in an atmospheric column comparable in size to a grid column used in a global atmospheric model. The required observations are made by a combination of in situ and remote sensing instruments. One of the greatest problems facing mankind at the present is climate change. Part of the problem is our limited ability to predict the regional patterns of climate change. In order to increase this ability, uncertainties in climate models must be reduced. One of the greatest of these uncertainties is the representation of clouds and cloud processes. This project, and ARM taken as a whole, has helped to improve the representation of clouds in global atmospheric models.
Krueger, Steven K.
Star Formation History across the Magellanic Clouds and other Local Group galaxies
The Ks magnitude distribution of asymptotic giant branch stars provides important constraints on the spatial variation of metallicity and mean-age of the stellar population of galaxies. Here, I present results of the investigation of these parameters across the Magellanic Clouds, M33, NGC 6822 and SagDIG and I discuss the tremendous improvement that new wide-field near-infrared instruments (i.e. VISTA) will provide on our understanding of the global intrinsic as well as dynamical history of these systems.
M. -R. L. Cioni
Microphysical and Radiative Effects of Ice Clouds on Tropical Equilibrium States: A Two-Dimensional Cloud-Resolving Modeling Study
The microphysical and radiative effects of ice clouds on tropical equilibrium states are investigated based on three two-dimensional cloud-resolving simulations imposed by zero vertical velocity and time-invariant zonal wind and sea surface ...
Fan Ping; Zhexian Luo; Xiaofan Li
Bringing Clouds into Focus: A New Global Climate Model May Reduce the
Bringing Clouds into Bringing Clouds into Focus Bringing Clouds into Focus A New Global Climate Model May Reduce the Uncertainty of Climate Forecasting May 11, 2010 | Tags: Lattice QCD Contact: John Hules, email@example.com , +1 510 486 6008 Randall-fig4.png The large data sets generated by the GCRM require new analysis and visualization capabilities. This 3D plot of vorticity isosurfaces was developed using VisIt, a 3D visualization tool with a parallel distributed architecture, which is being extended to support the geodesic grid used by the GCRM. (Image Courtesy of the NERSC Analytics Team) Clouds exert two competing effects on the Earth's temperature: they cool the planet by reflecting solar radiation back to space, but they also warm the planet by trapping heat near the surface. These two effects coexist in
The radiative influence of aerosol effects on liquid-phase cumulus clouds based on sensitivity studies with two climate models
A global black carbon aerosol model. J Geophys Res 101:of interactions between aerosols and cloud microphysics overby anthropogenic sulfate aerosol. J Geophys Res 106: 5279-
Menon, Surabi; Rotstayn, Leon
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
Fuel Cell Technologies Office: Transport Modeling Working Group
Transport Modeling Transport Modeling Working Group to someone by E-mail Share Fuel Cell Technologies Office: Transport Modeling Working Group on Facebook Tweet about Fuel Cell Technologies Office: Transport Modeling Working Group on Twitter Bookmark Fuel Cell Technologies Office: Transport Modeling Working Group on Google Bookmark Fuel Cell Technologies Office: Transport Modeling Working Group on Delicious Rank Fuel Cell Technologies Office: Transport Modeling Working Group on Digg Find More places to share Fuel Cell Technologies Office: Transport Modeling Working Group on AddThis.com... Key Activities Plans, Implementation, & Results Accomplishments Organization Chart & Contacts Quick Links Hydrogen Production Hydrogen Delivery Hydrogen Storage Fuel Cells Technology Validation
U.S. Army Modeling and Simulation Executable Architecture Deployment Cloud Virtualization Strategy
Our research has included leveraging Virtualization Technologies to provide integration, configuration and execution relief of Modeling & Simulation (M&S) event planning, instantiation and analysis. We have achieved this through a single service that ... Keywords: Virtualization, Cloud Computing, Modeling & Simulation (M&S), Distributed M&S, Hypervisor
Shaun Murphy; Scott Gallant; Chris Gaughan; Manny Diego
Numerical Simulation of Polar Lows and Comma Clouds Using Simple Dry Models
Linear and nonlinear numerical channel models are used to simulate polar low/comma cloud evolution. The purpose of this study is to see how much realism can be obtained using models that do not include water vapor. The study was inspired by ...
Stephen E. Mudrick
Towards building performance models for data-intensive workloads in public clouds
The cloud computing paradigm provides the "illusion" of infinite resources and, therefore, becomes a promising candidate for large-scale data-intensive computing. In this paper, we explore experiment-driven performance models for data-intensive workloads ... Keywords: multi-tenancy, performance model, performance variables, prediction techniques
Rizwan Mian; Patrick Martin; Farhana Zulkernine; Jose Luis Vazquez-Poletti
Low Clouds Contribute to Weather Prediction Model Bias | U.S. DOE Office of
Office of Science (SC) Website
2 2 » Low Clouds Contribute to Weather Prediction Model Bias Biological and Environmental Research (BER) BER Home About Research Facilities Science Highlights Searchable Archive of BER Highlights External link Benefits of BER Funding Opportunities Biological & Environmental Research Advisory Committee (BERAC) News & Resources Contact Information Biological and Environmental Research U.S. Department of Energy SC-23/Germantown Building 1000 Independence Ave., SW Washington, DC 20585 P: (301) 903-3251 F: (301) 903-5051 E: email@example.com More Information » November 2012 Low Clouds Contribute to Weather Prediction Model Bias Long-term measurement records improve the representation of clouds in climate and weather forecast models. Print Text Size: A A A Subscribe
GFDL ARM Project Technical Report: Using ARM Observations to Evaluate Cloud and Convection Parameterizations & Cloud-Convection-Radiation Interactions in the GFDL Atmospheric General Circulation Model
This report briefly summarizes the progress made by ARM postdoctoral fellow, Yanluan Lin, at GFDL during the period from October 2008 to present. Several ARM datasets have been used for GFDL model evaluation, understanding, and improvement. This includes a new ice fall speed parameterization with riming impact and its test in GFDL AM3, evaluation of model cloud and radiation diurnal and seasonal variation using ARM CMBE data, model ice water content evaluation using ARM cirrus data, and coordination of the TWPICE global model intercomparison. The work illustrates the potential and importance of ARM data for GCM evaluation, understanding, and ultimately, improvement of GCM cloud and radiation parameterizations. Future work includes evaluation and improvement of the new dynamicsPDF cloud scheme and aerosol activation in the GFDL model.
V. Ramaswamy; L. J. Donner; J-C. Golaz; S. A. Klein
Computational social dynamic modeling of group recruitment.
The Seldon software toolkit combines concepts from agent-based modeling and social science to create a computationally social dynamic model for group recruitment. The underlying recruitment model is based on a unique three-level hybrid agent-based architecture that contains simple agents (level one), abstract agents (level two), and cognitive agents (level three). This uniqueness of this architecture begins with abstract agents that permit the model to include social concepts (gang) or institutional concepts (school) into a typical software simulation environment. The future addition of cognitive agents to the recruitment model will provide a unique entity that does not exist in any agent-based modeling toolkits to date. We use social networks to provide an integrated mesh within and between the different levels. This Java based toolkit is used to analyze different social concepts based on initialization input from the user. The input alters a set of parameters used to influence the values associated with the simple agents, abstract agents, and the interactions (simple agent-simple agent or simple agent-abstract agent) between these entities. The results of phase-1 Seldon toolkit provide insight into how certain social concepts apply to different scenario development for inner city gang recruitment.
Berry, Nina M.; Lee, Marinna; Pickett, Marc; Turnley, Jessica Glicken (Sandia National Laboratories, Albuquerque, NM); Smrcka, Julianne D. (Sandia National Laboratories, Albuquerque, NM); Ko, Teresa H.; Moy, Timothy David (Sandia National Laboratories, Albuquerque, NM); Wu, Benjamin C.
A Simulation of a Squall Line Using a Nonhydrostatic Cloud Model with a 5-km Horizontal Grid
A three-dimensional nonhydrostatic cloud model is used to simulate the squall line observed in central Texas on 11 April 1979. The cloud model covers an area 400 � 400 km2 with a 5-km horizontal resolution and is supplied initial and boundary ...
Richard S. Hemler; Frank B. Lipps; Bruce B. Ross
Simulation of Aerosol-Cloud Interactions in the WRF Model at the Southern Great Plains Site
The aerosol direct and indirect effects were investigated for three specific cases during the March 2000 Cloud IOP at the SGP site by using a modified WRF model. The WRF model was previously altered to include a two-moment bulk microphysical scheme for the aerosol indirect effect and a modified Goddard shortwave radiation scheme for the aerosol direct effect. The three cases studied include a developing low pressure system, a low precipitation event of mainly cirrus clouds, and a cold frontal passage. Three different aerosol profiles were used with surface concentrations ranging from 210 cm-3 to 12,000 cm-3. In addition, each case and each aerosol profile was run both with and without the aerosol direct effect. Regardless of the case, increasing the aerosol concentration generally increased cloud water and droplet values while decreasing rain water and droplet values. Increased aerosols also decreased the surface shortwave radiative flux for every case; which was greatest when the aerosol direct effect was included. For convective periods during polluted model runs, the aerosol direct effect lowered the surface temperature and reduced convection leading to a lower cloud fraction. During most convective periods, the changes to cloud, rain, and ice water mixing ratios and number concentrations produced a nonlinear precipitation trend. A balance between these values was achieved for moderate aerosol profiles, which produced the highest convective precipitation rates. In non-convective cases, due to the presence of ice particles, aerosol concentration and precipitation amounts were positively correlated. The aerosol threshold between precipitation enhancement and suppression should be further studied for specific cloud types as well as for specific synoptic weather patterns to determine its precise values.
Vogel, Jonathan 1988-
Sensitivity of the Aerosol Indirect Effect to Subgrid Variability in the Cloud Parameterization of the GFDL Atmosphere General Circulation Model AM3
The recently developed GFDL Atmospheric Model version 3 (AM3), an atmospheric general circulation model (GCM), incorporates a prognostic treatment of cloud drop number to simulate the aerosol indirect effect. Since cloud drop activation depends on ...
Jean-Christophe Golaz; Marc Salzmann; Leo J. Donner; Larry W. Horowitz; Yi Ming; Ming Zhao
Mechanisms of Low Cloud�Climate Feedback in Idealized Single-Column Simulations with the Community Atmospheric Model, Version 3 (CAM3)
This study investigates the physical mechanism of low cloud feedback in the Community Atmospheric Model, version 3 (CAM3) through idealized single-column model (SCM) experiments over the subtropical eastern oceans. Negative cloud feedback is ...
Minghua Zhang; Christopher Bretherton
Experiments in Shower-Top Forecasting Using an Interactive One-Dimensional Cloud Model
Experiments were made in prediction of the elevation of warm season shower-tops, both prevailing and highest, using a one-dimensional cloud model run on a real-time minicomputer system. A forecaster inter-actively altered the initial temperatures ...
Timothy D. Crum; John J. Cahir
Two-Time-Level Semi-Lagrangian Modeling of Precipitating Clouds
This paper discusses two-time-level semi-Lagrangian approximations for the bulk warm-rain microphysics embedded in the framework of an anelastic cloud model. The central theoretical issue is a semi-Lagrangian integration of the rain-evolution ...
Wojciech W. Grabowski; Piotr K. Smolarkiewicz
Cloud-Top Entrainment Instability through Small-Scale Mixing and Its Parameterization in Numerical Models
In a recent paper, Kuo and Schubert demonstrated the lack of observational support for the relevance of the criterion for cloud-top entrainment instability proposed by Randall and by Deardorff. Here we derive a new criterion, based on a model of ...
M. K. MacVean; P. J. Mason
Modeling Cirrus Clouds. Part I: Treatment of Bimodal Size Spectra and Case Study Analysis
A model has been developed that predicts the evolution of bimodal size spectra in cirrus clouds. This was done by predicting two size distributions: one for ice particles less than about 150 �m and another for larger particles. The sum of these ...
David L. Mitchell; Steven K. Chai; Yangang Liu; Andrew J. Heymsfield; Yayi Dong
A Mixed Scheme for Subgrid-Scale Fluxes in Cloud-Resolving Models
A large-domain large-eddy simulation of a tropical deep convection system is used as a benchmark to derive and test a mixed subgrid-scale (SGS) scheme for scalar and momentum fluxes in cloud-resolving models (CRMs). The benchmark simulation ...
C.-H. Moeng; P. P. Sullivan; M. F. Khairoutdinov; D. A. Randall
Managing Smart Grid Information in the Cloud: Opportunities, Model, and Applications
Managing Smart Grid Information in the Cloud: Opportunities, Model, and Applications Xi Fang, AZ, USA New Mexico State University, Las Cruces, NM, USA Abstract--Smart Grid (SG), regarded applications. 1. INTRODUCTION Smart Grid (SG), an enhancement of the 20th century electrical grid, is regarded
Misra, Satyajayant
Cloud-radiative effects on implied oceanic energy transports as simulated by atmospheric general circulation models
This paper reports on energy fluxes across the surface of the ocean as simulated by fifteen atmospheric general circulation models in which ocean surface temperatures and sea-ice boundaries are prescribed. The oceanic meridional energy transport that would be required to balance these surface fluxes is computed, and is shown to be critically sensitive to the radiative effects of clouds, to the extent that even the sign of the Southern Hemisphere ocean energy transport can be affected by the errors in simulated cloud-radiation interactions.
Gleckler, P.J. [Lawrence Livermore National Lab., CA (United States); Randall, D.A. [Colorado State Univ., Fort Collins, CO (United States); Boer, G. [Canadian Climate Centre, Victoria (Canada)
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
TWP-ICE Data from the GEWEX Cloud System Study: Data Integration for Model Evaluation (GCSSDIME)
DOE Data Explorer (OSTI)
One of the most complete data sets of tropical cirrus and convection observations resulted from the Tropical Warm Pool - International Cloud Experiment (TWP-ICE) in the area around Darwin, Australia. The aim of the experiment is to examine convective cloud systems from their initial stages through the decaying and thin high level cirrus and measure their impact on the environment. The experiment design includes an unprecedented array of soundings and other information to support cloud resolving and other modeling studies as well as a large range of in-situ and remotely sensed observation platforms. A key component of the field campaign is a fleet of aircraft including the Dornier, Dimona, Egrett, Twin Otter, and Proteus. Together, these aircraft collected measurements of cloud properties and the meteorological environment from the planetary boundary layer up to 15 km high. The extensive ground network of cloud sensing radar, lidar and passive instruments are located on a ship and several ground sites throughout the experimental domain. This case study presents data from 19 Jan 2006 to 28 Feb 2006 and covers a region from 25S to 10S latitude and from 125E to 140E longitude.[Copied from http://gcss-dime.giss.nasa.gov/twp-ice/twp-ice.html
Posters A One-Dimensional Radiative Convective Model with Detailed Cloud Microphysics
5 5 Posters A One-Dimensional Radiative Convective Model with Detailed Cloud Microphysics J. Simmons, O. Lie-Svendsen, and K. Stamnes Geophysical Institute University of Alaska Fairbanks, Alaska The Arctic is a key element in determining the radiation budget of the earth. Within the polar regions, the net radiation (incoming solar radiation minus outgoing infrared radiation) is negative. To understand the role this energy deficit plays in the overall radiation budget, one must examine the prevalent atmospheric features of the Arctic. One such feature is a persistent layer of low-altitude, stratiform clouds found over the central Arctic predominantly from April to September (Tsay et al. 1984). These Arctic stratus clouds (ASC) modulate the earth's radiation budget
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
Ions and Precipitation Charging in Warm and Cold Clouds as Simulated in One-Dimensional Time-Dependent Models
One-dimensional time-dependent models of warm and cold clouds were constructed to test the electrical and precipitation development in the presence of a variety of charge separation mechanisms. The, models simulate charging by ion diffusion, the ...
I. Tzur; Z. Levin
PDF Parameterization of Boundary Layer Clouds in Models with Horizontal Grid Spacings from 2 to 16 km
Many present-day numerical weather prediction (NWP) models are run at resolutions that permit deep convection. In these models, however, the boundary layer turbulence and boundary layer cloud features are still grossly underresolved. ...
Vincent E. Larson; David P. Schanen; Minghuai Wang; Mikhail Ovchinnikov; Steven Ghan
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.
Cloud computing and electricity: beyond the utility model
Assessing the strengths, weaknesses, and general applicability of the computing-as-utility business model.
Erik Brynjolfsson; Paul Hofmann; John Jordan
Coupling Aerosol-Cloud-Radiative Processes in the WRF-Chem Model: Investigating the Radiative Impact of Elevated Point Sources
The local and regional influence of elevated point sources on summertime aerosol forcing and cloud-aerosol interactions in northeastern North America was investigated using the WRF-Chem community model. The direct effects of aerosols on incoming solar radiation were simulated using existing modules to relate aerosol sizes and chemical composition to aerosol optical properties. Indirect effects were simulated by adding a prognostic treatment of cloud droplet number and adding modules that activate aerosol particles to form cloud droplets, simulate aqueous phase chemistry, and tie a two-moment treatment of cloud water (cloud water mass and cloud droplet number) to an existing radiation scheme. Fully interactive feedbacks thus were created within the modified model, with aerosols affecting cloud droplet number and cloud radiative properties, and clouds altering aerosol size and composition via aqueous processes, wet scavenging, and gas-phase-related photolytic processes. Comparisons of a baseline simulation with observations show that the model captured the general temporal cycle of aerosol optical depths (AODs) and produced clouds of comparable thickness to observations at approximately the proper times and places. The model slightly overpredicted SO2 mixing ratios and PM2.5 mass, but reproduced the range of observed SO2 to sulfate aerosol ratios, suggesting that atmospheric oxidation processes leading to aerosol sulfate formation are captured in the model. The baseline simulation was compared to a sensitivity simulation in which all emissions at model levels above the surface layer were set to zero, thus removing stack emissions. Instantaneous, site-specific differences for aerosol and cloud related properties between the two simulations could be quite large, as removing above-surface emission sources influenced when and where clouds formed within the modeling domain. When summed spatially over the finest resolution model domain (the extent of which corresponds to the typical size of a single GCM grid cell) and temporally over a three day analysis period, total rainfall in the sensitivity simulation increased by 31% over that in the baseline simulation. Fewer optically thin clouds, arbitrarily defined as a cloud exhibiting an optical depth less than 1, formed in the sensitivity simulation. Domain-averaged AODs dropped from 0.46 in the baseline simulation to 0.38 in the sensitivity simulation. The overall net effect of additional aerosols attributable to primary particulates and aerosol precursors from point source emissions above the surface was a domain-averaged reduction of 5 W m-2 in mean daytime downwelling shortwave radiation.
Chapman, Elaine G.; Gustafson, William I.; Easter, Richard C.; Barnard, James C.; Ghan, Steven J.; Pekour, Mikhail S.; Fast, Jerome D.
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
Simulation of microphysical structure associated with tropical cloud clusters using mesoscale model and comparison with TRMM observations
An attempt has been made in the present study to examine the microphysical structure of a non-squall Tropical Cloud Cluster (TCC). Three-dimensional model simulations of cloud microphysical structure associated with a non-squall TCC occurred on 26 October ...
S. Abhilash; K. Mohankumar; S. Das
A Prognostic Parameterization for the Subgrid-Scale Variability of Water Vapor and Clouds in Large-Scale Models and Its Use to Diagnose Cloud Cover
A parameterization for the horizontal subgrid-scale variability of water vapor and cloud condensate is introduced, which is used to diagnose cloud fraction in the spirit of statistically based cloud cover parameterizations. High-resolution cloud-...
Adrian M. Tompkins
The Role of Radiation in Influencing Tropical Cloud Distributions in a Radiative�Convective Equilibrium Cloud-Resolving Model
Observations by Johnson et al. depict regions of active tropical convection as possessing increased relative humidity through a deep layer and reduced low-level static stability when compared to nonconvecting regions. Shallow cumulus clouds, ...
Lyle Pakula; Graeme L. Stephens
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.
A Theoretical Study of the Wet Removal of Atmospheric Pollutants. Part III: The Uptake, Redistribution, and Deposition of (NH4)2SO4 Particles by a Convective Cloud Using a Two-Dimensional Cloud Dynamics Model
Our model for the scavenging of aerosol particles has been coupled with the two-dimensional form of the convective cloud model of Clark and Collaborators. The combined model was then used to simulate a convective warm cloud for the meteorological ...
A. I. Flossmann; H. R. Pruppacher
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
Heat, Moisture, and Momentum Budgets of Isolated Deep Midlatitude and Tropical Convective Clouds as Diagnosed from Three-Dimensional Model Output. Part I: Control Experiments
This project uses a three-dimensional anelastic cloud model with a simple ice phase parameterization to evaluate the feedback between isolated deep convective clouds and their near surroundings. The horizontal Reynolds averaging approach of ...
Robert E. Schlesinger
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
Implementation of a Silver Iodide Cloud-Seeding Parameterization in WRF. Part I: Model Description and Idealized 2D Sensitivity Tests
A silver iodide (AgI) cloud-seeding parameterization has been implemented into the Thompson microphysics scheme of the Weather Research and Forecasting model to investigate glaciogenic cloud-seeding effects. The sensitivity of the parameterization ...
Lulin Xue; Akihiro Hashimoto; Masataka Murakami; Roy Rasmussen; Sarah A. Tessendorf; Daniel Breed; Shaun Parkinson; Pat Holbrook; Derek Blestrud
Evaluation of the Daylight Cycle of Model-Predicted Cloud Amount and Condensed Water Path over Europe with Observations from MSG SEVIRI
The evaluation of the diurnal cycle of cloud amount (CA) and cloud condensed water path (CWP) as predicted by climate models receives relatively little attention, mostly because of the lack of observational data capturing the diurnal cycle of ...
R. A. Roebeling; E. van Meijgaard
Long-Term Behavior of Cloud Systems in TOGA COARE and Their Interactions with Radiative and Surface Processes. Part I: Two-Dimensional Modeling Study
Two-dimensional cloud-resolving modeling of tropical cloud systems was performed for a 39-day period (5 December 1992 through 12 January 1993) during the Tropical Ocean Global Atmosphere (TOGA) Coupled Ocean�Atmosphere Response Experiment (COARE)...
Xiaoqing Wu; Wojciech W. Grabowski; Mitchell W. Moncrieff
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
Implementation of Prognostic Cloud Scheme for a Regional Spectral Model
The purpose of this study is to develop a precipitation physics package for the National Centers for Environmental Prediction (NCEP) Regional Spectral Model (RSM) designed to improve the skill of precipitation forecasts. The package incorporates ...
Song-You Hong; Hann-Ming Henry Juang; Qingyun Zhao
Cloud Model-Based Simulation of Spaceborne Radar Observations
Simulations of observations from potential spaceborne radars are made based on storm structure generated from the three-dimensional (3D) Goddard cumulus ensemble model simulation of an intense overland convective system. Five frequencies of 3, 10,...
H-Y. M. Yeh; N. Prasad; R. Meneghini; W-K. Tao; J. A. Jones; R. F. Adler
Understanding Albrecht's Model of Trade Cumulus Cloud Fields
Using Albrecht's model, approximate analytical formulas are found for the dependence of the steady-State mean thermodynamic structure of a partly cloudy convective marine boundary layer on external parameters. Our goals are 1) to understand the ...
Christopher S. Bretherton
An Improved Cloud Classification Algorithm Based on the SGP CART...
studies which need to group clouds according to cloud types, but also provides necessary information to implement different retrieval algorithms to generate integrated cloud...
ARM - Midlatitude Continental Convective Clouds - Single Column Model Forcing (xie-scm_forcing)
The constrained variational objective analysis approach described in Zhang and Lin [1997] and Zhang et al. [2001]was used to derive the large-scale single-column/cloud resolving model forcing and evaluation data set from the observational data collected during Midlatitude Continental Convective Clouds Experiment (MC3E), which was conducted during April to June 2011 near the ARM Southern Great Plains (SGP) site. The analysis data cover the period from 00Z 22 April - 21Z 6 June 2011. The forcing data represent an average over the 3 different analysis domains centered at central facility with a diameter of 300 km (standard SGP forcing domain size), 150 km and 75 km, as shown in Figure 1. This is to support modeling studies on various-scale convective systems.
Shaocheng Xie; Renata McCoy; Yunyan Zhang
Numerical simulation of self-induced rainout using a dynamic convective cloud model
The hypothesis that self-induced rainout can occur is supported by observations in Hiroshima and Nagasaki, where deposition of weapons debris with precipitation occurred several km downwind of the burst point. This precipitation was initiated either directly by the nuclear weapons or by the ensuing fires. Simulation of the Nagasaki event with a convection cloud precipitation scavenging model, although fraught with many questionable assumptions, agrees surprisingly well with the observations and supports the hypothesis that self-induced rainout can occur.
Molenkamp, C.R.
Convective Influence on the Heat Balance of the Tropical Tropopause Layer: A Cloud-Resolving Model Study
The tropical tropopause layer (TTL), and in particular the cold point tropopause, has been previously suggested as a feature decoupled from convection. Using a cloud-resolving model, the authors demonstrate that convection, in fact, has a cooling ...
Zhiming Kuang; Christopher S. Bretherton
Seasonal Simulations of the Planetary Boundary Layer and Boundary-Layer Stratocumulus Clouds with a General Circulation Model
The UCLA general circulation model (GCM) has been used to simulate the seasonally varying planetary boundary layer (PBL), as well as boundary-layer stratus and stratocumulus clouds. The PBL depth is a prognostic variable of the GCM, incorporated ...
David A. Randall; James A. Abeles; Thomas G. Corsetti
Toward an understanding of vertical momentum transports in cloud system resolving model simulations of multiscale tropical convection
This study examines the characteristics of convective momentum transport (CMT) and gravity wave momentum transport (GWMT) in two-dimensional cloud-system resolving model simulations, including the relationships between the two transports. A linear ...
Tiffany A. Shaw; Todd P. Lane
Predictive Capabilities of a One-Dimensional Convective Cloud Model with Forced Lifting and a New Entrainment Formulation
A one-dimensional time-dependent nonhydrostatic convective cloud model, with an entrainment formulation that includes the combined effects of turbulent and organized dynamic processes and forced lifting, is used to improve the forecasting of ...
Mladjen Curi?; Dejan Janc
Effects of Diurnal Variations on Tropical Equilibrium States: A Two-Dimensional Cloud-Resolving Modeling Study
Effects of diurnal variations on tropical heat and water vapor equilibrium states are investigated based on hourly data from two-dimensional cloud-resolving simulations. The model is integrated for 40 days and the simulations reach equilibrium ...
Shouting Gao; Yushu Zhou; Xiaofan Li
Radiative Transfer Simulations Using Mesoscale Cloud Model Outputs: Comparisons with Passive Microwave and Infrared Satellite Observations for Midlatitudes
Real midlatitude meteorological cases are simulated over western Europe with the cloud mesoscale model M�so-NH, and the outputs are used to calculate brightness temperatures at microwave frequencies with the Atmospheric Transmission at Microwave (...
Ingo Meirold-Mautner; Catherine Prigent; Eric Defer; Juan R. Pardo; Jean-Pierre Chaboureau; Jean-Pierre Pinty; Mario Mech; Susanne Crewell
Improving the representation of low clouds and drizzle in the ECMWF model based on ARM observations from the Azores.
In this study, the representation of marine boundary layer cloud is investigated in the ECMWF model using observations from the Atmospheric Radiation Measurement (ARM) mobile facility deployment to Graciosa Island in the North Atlantic. Systematic ...
Maike Ahlgrimm; Richard Forbes
Nonhydrostatic, Mesobeta-Scale Model Simulations of Cloud Ceiling and Visibility for an East Coast Winter Precipitation Event
Experiments are described that provide an example of the baseline skill level for the numerical prediction of cloud ceiling and visibility, where application to aviation-system safety and efficiency is emphasized. Model simulations of a light, ...
Mark T. Stoelinga; Thomas T. Warner
Stochastic Backscatter for Cloud-Resolving Models. Part I: Implementation and Testing in a Dry Convective Boundary Layer
In simulations of deep convection with cloud-resolving models the turbulence is often rather poorly resolved, and the influence of the subfilter-scale parameterization used in such circumstances is probably greater than in better-resolved ...
Sonja Weinbrecht; Paul J. Mason
A Simplified Model of the Walker Circulation with an Interactive Ocean Mixed Layer and Cloud-Radiative Feedbacks
Cloud�climate feedbacks between precipitation, radiation, circulation strength, atmospheric temperature and moisture, and ocean temperature are studied with an idealized model of the Walker circulation in a nonrotating atmosphere coupled to an ...
Matthew E. Peters; Christopher S. Bretherton
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 ...
H. Morrison; J. O. Pinto
Regional Model Simulations of Marine Boundary Layer Clouds over the Southeast Pacific off South America. Part I: Control Experiment
A regional climate model is used to simulate boundary layer stratocumulus (Sc) clouds over the southeast Pacific off South America during August�October 1999 and to study their dynamical, radiative, and microphysical properties and their ...
Yuqing Wang; Shang-Ping Xie; Haiming Xu; Bin Wang
Multiscale Convective Wave Disturbances in the Tropics: Insights from a Two-Dimensional Cloud-Resolving Model
Multiscale convective wave disturbances with structures broadly resembling observed tropical waves are found to emerge spontaneously in a nonrotating, two-dimensional cloud model forced by uniform cooling. To articulate the dynamics of these ...
Stefan N. Tulich; Brian E. Mapes
Group User Models for Personalized Hyperlink Recommendations
This paper presents a system that combines adaptive hypertext linking based on group link preferences with an implicit navigation-based mechanism for personalized link recommendations. A methodology using three Hebbian-style learning rules changes hyperlink ...
Johan Bollen
Observational and Model Estimates of Cloud Amount Feedback over the Indian and Pacific Oceans
Constraining intermodel spread in cloud feedback with observations is problematic because available cloud datasets are affected by spurious behavior in long-term variability. This problem is addressed by examining cloud amount in three independent ...
Katinka Bellomo; Amy C. Clement; Joel R. Norris; Brian J. Soden
Case Studies and Organisational Sustainability Modelling Presented by Cloud Computing Business Framework
In this paper, Cloud Computing Business Framework CCBF is proposed to help organisations achieve good Cloud design, deployment, migration, and services. Although organisations adopt Cloud Computing for Web Services, technical and business challenges ...
Gary Wills; Victor Chang; David De Roure; Robert John Walters
Modeling Study of Ice Formation in Warm-Based Precipitating Shallow Cumulus Clouds
Observations of large concentrations of ice particles in the dissipating stage of warm-based precipitating shallow cumulus clouds point to the limitations of scientists� understanding of the physics of such clouds and the possible role of cloud ...
Jiming Sun; Parisa A. Ariya; Henry G. Leighton; Man Kong Yau
Cloud resource usage: extreme distributions invalidating traditional capacity planning models
For years Capacity Planning professionals knew or suspected that various characteristics of computer usage have non-normal distribution. At the same time much of the traditional workload modeling and forecasting is based on mathematical techniques assuming ... Keywords: capacity planning, power law, probability distributions, resource usage, volatility
Charles Z. Loboz
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.
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.
Common Information Model (CIM) Users Group Fall 2011 Meeting Summary
For the first time, the Common Information Model Users Group (CIMug) meeting was held jointly with the other Utility Common Architecture International (UCAI) user groups (61850 Users Group, OpenSG Users Group, and UCAI Testing Committee). Combined attendance exceeded 200, with representation from 28 utilities, 26 vendors, 21 consulting companies, 3 universities, 14 research or standards groups, and 3 government or regulatory agencies. CIMug attendees heard CIM success stories from utilities around the wo...
Increase of Cloud Droplet Size with Aerosol Optical Depth: An Observational and Modeling Study
Cloud droplet effective radius (DER) is generally negatively correlated with aerosol optical depth (AOD) as a proxy of cloud condensation nuclei. In this study, cases of positive correlation were found over certain portions of the world by analyzing the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite products, together with a general finding that DER may increase or decrease with aerosol loading depending on environmental conditions. The slope of the correlation between DER and AOD is driven primarily by water vapor amount, which explains 70% of the variance in our study. Various potential artifacts that may cause the positive relation are investigated including water vapor swelling, partially cloudy, atmospheric dynamics, cloud three-dimensional (3-D) and surface influence effects. None seems to be the primary cause for the observed phenomenon, although a certain degree of influence exists for some of the factors. Analyses are conducted over seven regions around the world representing different types of aerosols and clouds. Only two regions show positive dependence of DER on AOD, near coasts of the Gulf of Mexico and South China Sea, which implies physical processes may at work. Using a 2-D spectral-bin microphysics Goddard Cumulus Ensemble model (GCE) which incorporated a reformulation of the K�hler theory, two possible physical mechanisms are hypothesized. They are related to the effects of slightly soluble organics (SSO) particles and giant CCNs. Model simulations show a positive correlation between DER and AOD, due to a decrease in activated aerosols with an increasing SSO content. Addition of a few giant CCNs also increases the DER. Further investigations are needed to fully understand and clarify the observed phenomenon.
Yuan, Tianle; Li, Zhanqing; Zhang, Renyi; Fan, Jiwen
I. Atmosphere Model Working Group (AMWG)
The AMWG used its development allocation for three main purposes: to understand, diagnose, and document the behavior of the Community Atmosphere Model (CAM3); to continue the evolution of the model beyond CAM3, including debugging and software engineering; and to understand and document aspects of the new functionality of the model. Substantial software engineering changes were made to CAM to more effectively isolate the points of interaction between model components and the rest of the CAM infrastructure. More components have an Earth System Modeling Framework (ESMF) type structure of "Initialize", "Run " and "Finalize, " which moves the model toward ESMF compatibility. We also made a number of changes to the model to facilitate the inclusion of other dynamical cores, particularly cores that will allow CAM to use model grids that are not oriented by latitude and longitude (e.g., cubed sphere and icosahedral/ triangular meshes). Extra software engineering features were also added, including Single Program-Multiple Data (SPMD) optimizations and extensions for CRAY and NEC platforms, changes to support IA64 clusters, and a number of bug fixes to improve
unknown authors
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
DISCL group Performance Model Directed Data Sieving
--control code for a thermo- stat and a nuclear reactor. We then pass the generated automata to the HyTech model prototype--written in MATLAB. We analyzed the control code for a simple thermostat and for a nuclear reactor. The theory of hybrid automata. In Logic in Computer Science, 1996. LICS '96. Proceedings., Eleventh
Gelfond, Michael
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
Vertical Velocity Focus Group
Velocity Focus Group Velocity Focus Group ARM 2008 Science Team Meeting Norfolk, VA March 10-14 Background Vertical velocity measurements have been at the top of the priority list of the cloud modeling community for some time. Doppler measurements from ARM profiling radars operating at 915-MHz, 35-GHz and 94-GHz have been largely unexploited. The purpose of this new focus group is to develop vertical velocity ARM products suitable for modelers. ARM response to their request has been slow. Most ARM instruments are suitable for cloud observations and have limited capabilities in precipitation Using ARM datasets for evaluating and improving cloud parameterization in global climate models (GCMs) is not straightforward, due to gigantic scale mismatches. Consider this... Looking only vertically drastically limits opportunities
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
Measurement and modeling of shortwave irradiance components in cloud-free atmospheres
Atmosphere scatters and absorbs incident solar radiation modifying its spectral content and decreasing its intensity at the surface. It is very useful to classify the earth-atmospheric solar radiation into several components--direct solar surface irradiance (E{sub direct}), diffuse-sky downward surface irradiance (E{sub diffuse}), total surface irradiance, and upwelling flux at the surface and at the top-of-the atmosphere. E{sub direct} depends only on the extinction properties of the atmosphere without regard to details of extinction, namely scattering or absorption; furthermore it can be accurately measured to high accuracy (0.3%) with the aid of an active cavity radiometer (ACR). E{sub diffuse} has relatively larger uncertainties both in its measurement using shaded pyranometers and in model estimates, owing to the difficulty in accurately characterizing pyranometers and in measuring model inputs such as surface reflectance, aerosol single scattering albedo, and phase function. Radiative transfer model simulations of the above surface radiation components in cloud-free skies using measured atmospheric properties show that while E{sub direct} estimates are closer to measurements, E{sub diffuse} is overestimated by an amount larger than the combined uncertainties in model inputs and measurements, illustrating a fundamental gap in the understanding of the magnitude of atmospheric absorption in cloud-free skies. The excess continuum type absorption required to reduce the E{sub diffuse} model overestimate ({approximately}3--8% absorptance) would significantly impact climate prediction and remote sensing. It is not clear at present what the source for this continuum absorption is. Here issues related to measurements and modeling of the surface irradiance components are discussed.
Halthore, R.N.
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
Competition of Precipitation Particles in a Model with Parameterized Cloud Microphysics
The nonlinear open system cloud is analyzed in this basic study in the context of the theory of self-organization. Emphasis is placed on the microphysical processes of riming, accretion, and sedimentation in a supercooled cloud containing several ...
Ulrike Wacker
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
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
Observations and Model Simulations of Transport and Precipitation Development in a Seeded Cumulus Congestus Cloud
Observations made by three instrumented aircraft, a Doppler radar, and other data sources were used to follow the initiation and development of precipitation in a small cumulus congestus cloud. The cloud was seeded at its base using an airborne ...
Michael W. Huston; Andrew G. Detwiler; Fred J. Kopp; Jeffrey L. Stith
Cloud Shading Retrieval and Assimilation in a Satellite-Model Coupled Mesoscale Analysis System
A retrieval-assimilation method has been developed as a quantitative means to exploit the information in satellite imagery regarding shading of the ground by clouds, as applied to mesoscale weather analysis. Cloud radiative parameters are ...
Alan E. Lipton
Urban traffic flow forecasting using Gauss-SVR with cat mapping, cloud model and PSO hybrid algorithm
In order to improve forecasting accuracy of urban traffic flow, this paper applies support vector regression (SVR) model with Gauss loss function (namely Gauss-SVR) to forecast urban traffic flow. By using the input historical flow data as the validation ... Keywords: Cat mapping, Chaos theory, Cloud model, Particle Swarm Optimization, Support vector regression, Traffic flow forecasting
Ming-Wei Li; Wei-Chiang Hong; Hai-Gui Kang
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
Accounting for Unresolved Spatial Variability in Large Scale Models: Development and Evaluation of a Statistical Cloud Parameterization with Prognostic Higher Order Moments
This project focused on the variability of clouds that is present across a wide range of scales ranging from the synoptic to the millimeter. In particular, there is substantial variability in cloud properties at scales smaller than the grid spacing of models used to make climate projections (GCMs) and weather forecasts. These models represent clouds and other small-scale processes with parameterizations that describe how those processes respond to and feed back on the largescale state of the atmosphere.
Robert Pincus
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
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
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...
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
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
The Numerical Simulation of Clouds, Rains and Airflow over the Vosges and Black Forest Mountains: A Meso-? Model with Parameterized Microphysics
A three-dimensional meso-? model with parameterized microphysics is presented. The model is capable of simulating orographically forced clouds, rain, and airflow. Tests using a two-dimensional version confirm the ability of the model to replicate ...
Everett C. Nickerson; Evelyne Richard; Robert Rosset; David R. Smith
Aerosol, Cloud, and Climate: From Observation to Model (457th Brookhaven Lecture)
In the last 100 years, the Earth has warmed by about 1�F, glaciers and sea ice have been melting more quickly than previously, especially during the past decade, and the level of the sea has risen about 6-8 inches worldwide. Scientists have long been investigating this phenomenon of �global warming,� which is believed to be at least partly due to the increased carbon dioxide (CO2) concentration in the air from burning fossil fuels. Funded by DOE, teams of researchers from BNL and other national labs have been gathering data in the U.S. and internationally to build computer models of climate and weather to help in understanding general patterns, causes, and perhaps, solutions. Among many findings, researchers observed that atmospheric aerosols, minute particles in the atmosphere, can significantly affect global energy balance and climate. Directly, aerosols scatter and absorb sunlight. Indirectly, increased aerosol concentration can lead to smaller cloud droplets, changing clouds in ways that tend to cool global climate and potentially mask overall warming from man-made CO2.
Wang, Jian (Ph.D., Environmental Sciences Department)
Reserved or On-Demand Instances? A Revenue Maximization Model for Cloud Providers
We examine the problem of managing a server farm in a way that attempts to maximize the net revenue earned by a cloud provider by renting servers to customers according to a typical Platform-as-a-Service model. The Cloud provider offers its resources to two classes of customers: `premium' and `basic'. Premium customers pay upfront fees to reserve servers for a specified period of time (e.g. a year). Premium customers can submit jobs for their reserved servers at any time and pay a fee for the server-hours they use. The provider is liable to pay a penalty every time a `premium' job can not be executed due to lack of resources. On the other hand, `basic' customers are served on a best-effort basis, and pay a server-hour fee that may be higher than the one paid by premium customers. The provider incurs energy costs when running servers. Hence, it has an incentive to turn off idle servers. The question of how to choose the number of servers to allocate to each pool (basic and premium) is answered by analyzing a s...
Mazzucco, Michele
Urban modeling based on segmentation and regularization of airborne lidar point clouds
This paper presents an approach to process raw lidar 3-D point clouds over urban area and extract terrain, buildings and other urban features. In the initial step, �non-ground points � are separated from ground points using a one dimensional filtering process based on the slope between two consecutive points in the point cloud and the terrain elevation in the vicinity of the points. In the next step, the non-ground point dataset is processed to segment individual buildings. This is accomplished by using a 3-D regional growing approach. At the end of this step, each lidar point is attributed to a building. The first step towards building reconstruction is to obtain an approximate footprint of the building, which is accomplished by extracting the points on the building boundary by a modified convex hull algorithm. Once the footprint boundary points are found, their edges are regularized by using a least squares model to form the final building shape. Mathematic formulation of 3D region growing and boundary regularization is presented. Tests results of reconstructed buildings over complex urban areas are reported. 1.
Aparajithan Sampath; Jie Shan
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
Observations and Modeling of Shallow Convective Clouds: Implications for the Indirect Aerosol Effects
Observations Observations and Modeling of Shallow Convective Clouds: Implications for the Indirect Aerosol Effects Sylwester Arabas 1 , Joanna Slawinska 1 , Wojciech Grabowski 2 , Hugh Morrison 2 , Hanna Pawlowska 1 1 : Institute of Geophysics, University of Warsaw, Poland 2 : National Center for Atmospheric Research, Boulder, Colorado, USA 348 constants for reference state and lateral boundary conditions 349 ibcx=icyx 350 ibcy=icyy*j3 351 ibcz=icyz 352 irlx=irelx 353 irly=irely*j3 354 irdbc=0 355 fcr0=fcr0*icorio 356 itdl=0 357 tdt=40.*3600. 358 u0tdl=u00 359 360 361 constants for thermodynamics 362 c bv=sqrt(st*g) 363 bv=st 364 st=bv**2/g 365 cp=3.5*rg 366 cap=rg/cp 367 pr00=rg*rh00*tt00
Tropical and subtropical cloud transitions in weather and climate prediction models: the GCSS/WGNE Pacific Cross-Section Intercomparison (GPCI)
A model evaluation approach is proposed where weather and climate prediction models are analyzed along a Pacific Ocean cross-section, from the stratocumulus regions off the coast of California, across the shallow convection dominated trade-winds, to the deep convection regions of the ITCZ: the GCSS/WGNE Pacific Cross-section Intercomparison (GPCI). The main goal of GPCI is to evaluate, and help understand and improve the representation of tropical and sub-tropical cloud processes in weather and climate prediction models. In this paper, a detailed analysis of cloud regime transitions along the cross-section from the sub-tropics to the tropics for the season JJA of 1998 is presented. This GPCI study confirms many of the typical weather and climate prediction model problems in the representation of clouds: underestimation of clouds in the stratocumulus regime by most models with the corresponding consequences in terms of shortwave radiation biases; overestimation of clouds by the ECMWF Re-Analysis (ERA40) in the deep tropics (in particular) with the corresponding impact in the outgoing longwave radiation; large spread between the different models in terms of cloud cover, liquid water path and shortwave radiation; significant differences between the models in terms of vertical crosssections of cloud properties (in particular), vertical velocity and relative humidity. An alternative analysis of cloud cover mean statistics is proposed where sharp gradients in cloud cover along the GPCI transect are taken into account. This analysis shows that the negative cloud bias of some models and ERA40 in the stratocumulus regions (as compared to ISCCP) is associated not only with lower values of cloud cover in these regimes, but also with a stratocumulus-to-cumulus transition that occurs too early along the trade-wind Lagrangian trajectory. Histograms of cloud cover along the cross-section differ significantly between models. Some models exhibit a quasi-bimodal structure with cloud cover being either very large (close to 100%) or very small, while other models show a more continuous transition. The ISCCP observations suggest that reality is in-between these two extreme examples. These different patterns reflect the diverse nature of the cloud, boundary layer, and convection parameterizations in the participating weather and climate prediction models.
Teixeira, J.; Cardoso, S.; Bonazzola, M.; Cole, Jason N.; DelGenio, Anthony D.; DeMott, C.; Franklin, A.; Hannay, Cecile; Jakob, Christian; Jiao, Y.; Karlsson, J.; Kitagawa, H.; Koehler, M.; Kuwano-Yoshida, A.; LeDrian, C.; Lock, Adrian; Miller, M.; Marquet, P.; Martins, J.; Mechoso, C. R.; Meijgaard, E. V.; Meinke, I.; Miranda, P.; Mironov, D.; Neggers, Roel; Pan, H. L.; Randall, David A.; Rasch, Philip J.; Rockel, B.; Rossow, William B.; Ritter, B.; Siebesma, A. P.; Soares, P.; Turk, F. J.; Vaillancourt, P.; Von Engeln, A.; Zhao, M.
A closure for updraft-downdraft representation of subgrid-scale fluxes in cloud-resolving models
A closure relationship between subgrid-scale (SGS) updraft-downdraft differences and resolvable-scale (RS) variables is proposed and tested for cloud-resolving models (CRMs), based on a data analysis of a large-eddy simulation (LES) of deep ...
Chin-Hoh Moeng
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
Effects of diurnal variation on a tropical coupling system: a 2-dimensional coupled ocean-cloud resolving atmosphere modeling study
The effects of diurnal variation on tropical atmospheric and oceanic variability are investigated with a two-dimensional coupled ocean-cloud resolving atmosphere model. The experiment with a time-invariant solar zenith angle is compared to the control ... Keywords: diurnal variation, tropical coupling system
Shouting Gao; Yushu Zhou
Millimeter wave scattering from ice crystals and their aggregates: Comparing cloud model simulations with X and Kaband
of the relative amounts of cloud liquid and ice. Modeling studies have shown that the poorly understood ice phase parameterizations has proven to be a difficult task. This study evaluates results of different ice microphysics conclusions about the appropriateness of different CRM ice microphysics parameterizations. Citation: Botta, G
Infinite cloud model of electrification by the precipitation mechanism in the presence of high rates of ion generation
We have extended a simple, infinite cloud, precipitation mechanism model of thundercloud electrification to include effects due to the presence of radioactive aerosol particles resulting from fresh debris from a nuclear explosion. These effects involve ion generation, currents due to motions of ions and charged aerosol particles, and collection of ions and aerosol particles by hydrometeors and cloud droplets. Our conclusion is that an ion pair generation rate G> or approx. =10/sup 12/m/sup -3/ s/sup -1/ will prevent significant electric field growth.
Spangler, J.D.; Rosenkilde, C.E.
Infinite cloud model of electrification by the precipitation mechanism in the pressence of high rates of ion generation
We have extended a simple, infinite-cloud, precipitation-mechanism model of thundercloud electrification to include effects due to the presence of radioactive aerosol particles. These effects involve ion generation, currents due to motions of ions and charged aerosol particles, and collection of ions and aerosol particles by hydrometeors and cloud droplets. Our conclusion is that an ion-pair generation rate G equal to or greater than 10/sup 12/m/sup -3/s/sup -1/ will prevent significant electric-field growth.
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
Statistical Description of Radiation Transfer in Clouds
The statistical characteristics of simulated cloud fields constructed based on Poisson point fluxes are studied. The input parameters of mathematical models of cloudiness include the cloud fraction and the mean horizontal size of clouds ...
Georgi A. Titov
A Survey on Cloud Provider Security
A Survey on Cloud Provider Security Measures Alex Pucher, Stratos Dimopoulos Abstract Cloud take advantage of this model already, but security and privacy concerns limit the further adoption agencies and start offering security certifications and separate tightly controlled "government" cloud
Radiative Effects of Cloud-Type Variations
Radiative flux changes induced by the occurrence of different cloud types are investigated using International Satellite Cloud Climatology Project cloud data and a refined radiative transfer model from National Aeronautics and Space ...
Ting Chen; William B. Rossow; Yuanchong Zhang
Correcting transport errors during advection of aerosol and cloud moment sequences in eulerian models
Moment methods are finding increasing usage for simulations of particle population balance in box models and in more complex flows including two-phase flows. These highly efficient methods have nevertheless had little impact to date for multi-moment representation of aerosols and clouds in atmospheric models. There are evidently two reasons for this: First, atmospheric models, especially if the goal is to simulate climate, tend to be extremely complex and take many man-years to develop. Thus there is considerable inertia to the implementation of novel approaches. Second, and more fundamental, the nonlinear transport algorithms designed to reduce numerical diffusion during advection of various species (tracers) from cell to cell, in the typically coarse grid arrays of these models, can and occasionally do fail to preserve correlations between the moments. Other correlated tracers such as isotopic abundances, composition of aerosol mixtures, hydrometeor phase, etc., are subject to this same fate. In the case of moments, this loss of correlation can and occasionally does give rise to unphysical moment sets. When this happens the simulation can come to a halt. Following a brief description and review of moment methods, the goal of this paper is to present two new approaches that both test moment sequences for validity and correct them when they fail. The new approaches work on individual grid cells without requiring stored information from previous time-steps or neighboring cells.
McGraw R.
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
Carbon Dioxide and Climate: Mechanisms of Changes in Cloud
Changes in cloud distribution may provide a major feedback on climate change. General circulation model simulations show an upward shift of high cloud and a general reduction of free-tropospheric cloud when climate warms. The shift of high cloud ...
J. F. B. Mitchell; W. J. Ingram
The effect of horizontal resolution on cloud radiative forcing in the ECMWF model. PCMDI report No. 22
With expanding computer capability and capacity there has been considerable interest in increasing the resolution in GCMs. The primary driving force behind this are two fold: (1) increased resolution may reduce the systematic errors inherent in parameterization of sub-grid scale processes, and (2) higher resolution may improve confidence in regional scale studies of climatic features that are orographically influenced -- such as the effect of the Tibetan Plateau on the East Asian Monsoon. This study focuses on the effect of horizontal resolution on the spatial and temporal systematic errors of cloud radiative forcing and its components. In this paper, the top-of-the-atmosphere radiation fields are taken from a series of simulations using the European Centre for Medium Range Forecasts (ECMWF) general circulation model (cycle 33), run at four different horizontal resolutions. Section 2 discusses the concept of cloud radiative forcing and describes the simulations from the ECMWF model. The observed global field of cloud forcing from ERBE is presented in section 3 along with the model-produced fields of the net solar and longwave cloud forcing. The seasonal effect of forcing is described in section 4, and the results are summarized in section 5.
Potter, G.L.
On the Application of the Dynamic Smagorinsky Model to Large-Eddy Simulations of the Cloud-Topped Atmospheric Boundary Layer
In this paper the dynamic Smagorinsky model originally developed for engineering flows is adapted for simulations of the cloud-topped atmospheric boundary layer in which an anelastic form of the governing equations is used. The adapted model ...
M. P. Kirkpatrick; A. S. Ackerman; D. E. Stevens; N. N. Mansour
Understanding the Importance of Microphysics and Macrophysics for Warm Rain in Marine Low Clouds. Part II: Heuristic Models of Rain Formation
Two simple heuristic model formulations for warm rain formation are introduced and their behavior explored. The first, which is primarily aimed at representing warm rain formation in shallow convective clouds, is a continuous collection model ...
Robert Wood; Terence L. Kubar; Dennis L. Hartmann
Effects of Downdrafts and Mesoscale Convective Organization on the Heat and Moisture Budgets of Tropical Cloud Clusters. Part I: A Diagnostic Cumulus Ensemble Model
A diagnostic cumulus ensemble model is developed to study the effects of convective-scale downdrafts and mesoscale convective organization on the heat and moisture budgets of tropical cloud clusters. The model adopts the spectral representation ...
Ming-Dean Cheng
A Parameterization for Land�Atmosphere-Cloud Exchange (PLACE): Documentation and Testing of a Detailed Process Model of the Partly Cloudy Boundary Layer over Heterogeneous Land
This paper presents a general description of, and demonstrates the capabilities of, the Parameterization for Land�Atmosphere�Cloud Exchange (PLACE). The PLACE model is a detailed process model of the partly cloudy atmospheric boundary layer and ...
Peter J. Wetzel; Aaron Boone
Multiscale Interactions in the Life Cycle of a Tropical Cyclone Simulated in a Global Cloud-System-Resolving Model. Part II: System-Scale and Mesoscale Processes
The life cycle of Tropical Storm Isobel was simulated reasonably well in the Nonhydrostatic Icosahedral Atmospheric Model (NICAM), a global cloud-system-resolving model. The evolution of the large-scale circulation and the storm-scale structure ...
Hironori Fudeyasu; Yuqing Wang; Masaki Satoh; Tomoe Nasuno; Hiroaki Miura; Wataru Yanase
Cirrus Parcel Model Comparison Project. Phase 1: The Critical Components to Simulate Cirrus Initiation Explicitly
The Cirrus Parcel Model Comparison Project, a project of the GCSS [Global Energy and Water Cycle Experiment (GEWEX) Cloud System Studies] Working Group on Cirrus Cloud Systems, involves the systematic comparison of current models of ice crystal ...
Ruei-Fong Lin; David O'C. Starr; Paul J. DeMott; Richard Cotton; Kenneth Sassen; Eric Jensen; Bernd K�rcher; Xiaohong Liu
A Comparison of TWP-ICE Observational Data with Cloud-Resolving Model Results
Observations made during the TWP-ICE campaign are used to drive and evaluate thirteen cloud-resolving model simulations with periodic lateral boundary conditions. The simulations employ 2D and 3D dynamics, one- and two-moment microphysics, several variations on large-scale forcing, and the use of observationally derived aerosol properties to prognose droplet numbers. When domain means are averaged over a 6-day active monsoon period, all simulations reproduce observed surface precipitation rate but not its structural distribution. Simulated fractional areas covered by convective and stratiform rain are uncorrelated with one another, and are both variably overpredicted by up to a factor of {approx}2. Stratiform area fractions are strongly anticorrelated with outgoing longwave radiation (OLR) but are negligibly correlated with ice water path (IWP), indicating that ice spatial distribution controls OLR more than mean IWP. Overpredictions of OLR tend to be accompanied by underpredictions of reflected shortwave radiation (RSR). When there are two simulations differing only in microphysics scheme or large-scale forcing, the one with smaller stratiform area tends to exhibit greater OLR and lesser RSR by similar amounts. After {approx}10 days, simulations reach a suppressed monsoon period with a wide range of mean precipitable water vapor, attributable in part to varying overprediction of cloud-modulated radiative flux divergence compared with observationally derived values. Differences across the simulation ensemble arise from multiple sources, including dynamics, microphysics, and radiation treatments. Close agreement of spatial and temporal averages with observations may not be expected, but the wide spreads of predicted stratiform fraction and anticorrelated OLR indicate a need for more rigorous observation-based evaluation of the underlying micro- and macrophysical properties of convective and stratiform structures.
Fridlind, A. M.; Ackerman, Andrew; Chaboureau, Jean-Pierre; Fan, Jiwen; Grabowski, Wojciech W.; Hill, A.; Jones, T. R.; Khaiyer, M. M.; Liu, G.; Minnis, Patrick; Morrison, H.; Nguyen, L.; Park, S.; Petch, Jon C.; Pinty, Jean-Pierre; Schumacher, Courtney; Shipway, Ben; Varble, A. C.; Wu, Xiaoqing; Xie, Shaocheng; Zhang, Minghua
The Mesoscale and Microscale Structure and Organization of Clouds and Precipitation in Midlatitude Cyclones. VIII: A Model for the �Seeder-Feeder� Process in Warm-Frontal Rainbands
Previous field studies have indicated that warm-frontal rainbands form when ice particles from a �seeder� cloud grow as they fall through a lower-level �feeder� cloud. In this paper we present results from a parameterized numerical model of the ...
Steven A. Rutledge; Peterv Hobbs
Modeling throughput sampling size for a cloud-hosted data scheduling and optimization service
As big-data processing and analysis dominates the usage of the Cloud systems, the need for Cloud-hosted data scheduling and optimization services increases. One key component for such a service is to provide available bandwidth and achievable throughput ... Keywords: Distributed applications, Distributed systems, Network protocols, Optimization
Esma Yildirim, Jangyoung Kim, Tevfik Kosar
Open Energy Info (EERE)
groups/all/feed en Buildings groups/all/feed en Buildings http://en.openei.org/community/group/buildings Description: This group is dedicated to discussions about green buildings, energy use in buildings, occupant comfort in buildings, and building technologies. The OpenEI Buildings Community Group will be dedicated to discussions, blogs, and postings about new building technologies, green buildings, energy use in buildings, and occupant experience (comfort levels) in green buildings.group/buildings" target="_blank">read more architecture building reviews buildings technology comfort energy use facilities management green building LEED technologies usgbc
Sensitivity Studies of Dust Ice Nuclei Effect on Cirrus Clouds with the Community Atmosphere Model CAM5
In this study the effect of dust aerosol on upper tropospheric cirrus clouds through heterogeneous ice nucleation is investigated in the Community Atmospheric Model version 5 (CAM5) with two ice nucleation parameterizations. Both parameterizations consider homogeneous and heterogeneous nucleation and the competition between the two mechanisms in cirrus clouds, but differ significantly in the number concentration of heterogeneous ice nuclei (IN) from dust. Heterogeneous nucleation on dust aerosol reduces the occurrence frequency of homogeneous nucleation and thus the ice crystal number concentration in the Northern Hemisphere (NH) cirrus clouds compared to simulations with pure homogeneous nucleation. Global and annual mean shortwave and longwave cloud forcing are reduced by up to 2.0 � 0.1 W m?2 (1? uncertainty) and 2.4 � 0.1 W m?2, respectively due to the presence of dust IN, with the net cloud forcing change of ?0.40 � 0.20 W m?2. Comparison of model simulations with in situ aircraft data obtained in NH mid-latitudes suggests that homogeneous ice nucleation may play an important role in the ice nucleation at these regions with temperatures of 205�230 K. However, simulations overestimate observed ice crystal number concentrations in the tropical tropopause regions with temperatures of 190�205 K, and overestimate the frequency of occurrence of high ice crystal number concentration (> 200 L?1) and underestimate the frequency of low ice crystal number concentration (< 30 L?1) at NH mid-latitudes. These results highlight the importance of quantifying the number concentrations and properties of heterogeneous IN (including dust aerosol) in the upper troposphere from the global perspective.
Liu, Xiaohong; Shi, Xiangjun; Zhang, Kai; Jensen, Eric; Gettelman, A.; Barahona, Donifan; Nenes, Athanasios; Lawson, Paul
Antilinear deformations of Coxeter groups, an application to Calogero models
We construct complex root spaces remaining invariant under antilinear involutions related to all Coxeter groups. We provide two alternative constructions: One is based on deformations of factors of the Coxeter element and the other based on the deformation of the longest element of the Coxeter group. Motivated by the fact that non-Hermitian Hamiltonians admitting an antilinear symmetry may be used to define consistent quantum mechanical systems with real discrete energy spectra, we subsequently employ our constructions to formulate deformations of Coxeter models remaining invariant under these extended Coxeter groups. We provide explicit and generic solutions for the Schroedinger equation of these models for the eigenenergies and corresponding wavefunctions. A new feature of these novel models is that when compared with the undeformed case their solutions are usually no longer singular for an exchange of an amount of particles less than the dimension of the representation space of the roots. The simultaneous scattering of all particles in the model leads to anyonic exchange factors for processes which have no analogue in the undeformed case.
Andreas Fring; Monique Smith
Satellite-based remote sensing of cirrus clouds: hyperspectral radiative transfer modeling, analysis of uncertainties in in-situ cloud extinction measurements and intercomparison of cirrus retrievals from a-train instruments
This dissertation consists of three parts, each devoted to a particular issue of significant importance for satellite-based remote sensing of cirrus clouds. In the first part, we develop and present a fast infrared radiative transfer model on the basis of the adding-doubling principle. The model aims to facilitate the radiative transfer computations involved in hyperspectral remote sensing applications. The model is applicable to a variety of cloud conditions, including vertically inhomogeneous or multilayered clouds. It is shown that for hyperspectral applications the model is two order-of-magnitude faster than the well-known discrete ordinate transfer (DISORT) model, while maintains a similar accuracy. The second part is devoted to the investigation of uncertainties in the FSSP (Forward Scattering Spectrometer Probe) measurement of cloud extinction by small ice particles. First, the single-scattering properties of small ice particles in cirrus clouds are derived and compared to those of equivalent spheres according to various definitions. It is found that, although small ice particles in cirrus clouds are often �quasi-spherical�, their scattering phase functions and asymmetry factors are significant different from those of ice spheres. Such differences may lead to substantial underestimation of cloud extinction in FSSP measurement, if small ice particles are assumed to be spheres. In the third part, we present a comparison of cirrus cloud optical thickness retrievals from two important instruments, MODIS (Moderate Resolution Imaging Spectrometer) and POLDER (Polarization and Directionality of Earth�s Reflection), on board NASA�s A-train satellite constellation. The comparison reveals a large difference. Several possible reasons are discussed. It is found that much of the difference is attributable to the difference between the MODIS and POLDER retrieval algorithm in the assumption of cirrus cloud bulk scattering properties. Potential implications of the difference for climate studies are investigated. An important finding is that the use of an unrealistic cirrus bulk scattering model might introduce artificial seasonal variation of cirrus optical thickness and shortwave radiative forcing into the retrieval.
Zhang, Zhibo
Orographic Clouds in Terrain-Blocked Flows: An Idealized Modeling Study
Idealized numerical simulations of moist strongly stratified flow over topography are used to study the processes that control orographic clouds in terrain-blocked flows as a joint function of the nondimensional flow parameter Nh/U, the ...
Joseph Galewsky
Direct Numerical Simulations of a Smoke Cloud�Top Mixing Layer as a Model for Stratocumuli
A radiatively driven cloud-top mixing layer is investigated using direct numerical simulations. This configuration mimics the mixing process across the inversion that bounds the stratocumulus-topped boundary layer. The main focus of this paper is ...
Alberto de Lozar; Juan Pedro Mellado
Combined Observational and Model Investigations of the Z�LWC Relationship in Stratocumulus Clouds
In situ measurements indicate the complexity and nonunique character of radar reflectivity�liquid water content (Z�LWC) relationships in stratocumulus and cumulus clouds. Parameters of empirical (statistical) Z�LWC dependences vary within a wide ...
A. Khain; M. Pinsky; L. Magaritz; O. Krasnov; H. W. J. Russchenberg
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
Cloud Modeling Tests of the ULTIMATE�MACHO Scalar Advection Scheme
Numerical diffusion can be minimized using fine grid spacing and/or higher-order numerical schemes. In this study, the authors focus on higher-order scalar advection schemes and their effects on simulated cloud fields. A monotonic multidimensional ...
Takanobu Yamaguchi; David A. Randall; Marat F. Khairoutdinov
A Study of Two Cases of Comma-Cloud Cyclogenesis Using a Semigeostrophic Model
The linear stability of two atmospheric flows is examined, with basic-state data taken from environments where comma clouds were observed to form. The basic states each feature a baroclinic zone associated with an upper-level jet, with ...
George C. Craig; Han-Ru Cho
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
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
A New Parameterization of an Asymmetry Factor of Cirrus Clouds for Climate Models
The aspect ratio (AR) of a nonspherical ice particle is identified as the key microphysical parameter to determine its asymmetry factor for solar radiation. The mean effective AR is defined for cirrus clouds containing various nonspherical ice ...
Prediction of In-Cloud Icing Conditions at Ground Level Using the WRF Model
In-cloud icing on aircraft and ground structures can be observed every winter in many countries. In extreme cases ice can cause accidents and damage to infrastructure such as power transmission lines, telecommunication towers, wind turbines, ski ...
Bj�rn Egil Kringlebotn Nygaard; J�n Egill Kristj�nsson; Lasse Makkonen
CO2 Retrieval over Clouds from the OCO Mission: Model Simulations and Error Analysis
Spectral characteristics of the future Orbiting Carbon Observatory (OCO) sensor, which will be launched in January 2009, were used to infer the carbon dioxide column-averaged mixing ratio over liquid water clouds over ocean by means of radiative ...
J�r�me Vidot; Ralf Bennartz; Christopher W. O�Dell; Ren� Preusker; Rasmus Lindstrot; Andrew K. Heidinger
Transport Modeling Working Group Transport Modeling Working Group The Transport Modeling Working Group meets twice per year to exchange information, create synergies, share experimental and computational results, and collaboratively develop methodologies for and understanding of transport phenomena in polymer electrolyte fuel cell stacks. Its members include principle investigators and supporting personnel from transport-related projects funded by the U.S. Department of Energy (DOE). Learn more about DOE research activities can be found in the Multi-Year Research, Development, and Demonstration Plan. Description Technical Targets Meetings Contacts Description Fuel cell operation relies on effective mass transport of species through individual components and across the interfaces between components. Among these species are hydrogen, oxygen, water, protons, and electrons. Transport behavior is a function of operating conditions and component properties such as microstructure and surface properties. Understanding and optimizing the controlling transport phenomena are critical to the efficient and cost-effective operation of polymer electrolyte fuel cells. A better understanding of mass transport in the fuel cell, especially of water, has the potential to lead to improved designs and more efficient systems.
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
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
The Sensitivity of the Outgoing Longwave Radiation to Surface Temperature: Modeling the Opacity Feedback and Experiments with a Variable Cloud-Top Temperature Provision
An efficient longwave scheme for climate models originally suggested by Sasamori is modified to correctly simulate the water vapor-temperature feedback mechanism. It is found that the modified scheme with a fixed cloud-top altitude (FCA) ...
Binyamin U. Neeman; Joachim H. Joseph; George Ohring
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
A Modeling Study of the Influence of Ice Scavenging on the Chemical Composition of Liquid-Phase Precipitation of a Cumulonimbus Cloud
Evidence of the efficient removal of chemicals by ice particles has been deduced from past field experiments and laboratory studies. However, the ice phase has been poorly represented in prior cloud chemistry modeling. This paper uses a two-...
Nicole Audiffren; Sylvie Cautenet; Nadine Chaumerliac
The 13�14 December 2001 IMPROVE-2 Event. Part II: Comparisons of MM5 Model Simulations of Clouds and Precipitation with Observations
This paper compares airborne in situ observations of cloud microphysical parameters with the fifth-generation Pennsylvania State University�National Center for Atmospheric Research (PSU�NCAR) Mesoscale Model (MM5) simulations, using the Reisner-2 ...
Matthew F. Garvert; Christopher P. Woods; Brian A. Colle; Clifford F. Mass; Peter V. Hobbs; Mark T. Stoelinga; Justin B. Wolfe
Sea Surface Temperature Biases under the Stratus Cloud Deck in the Southeast Pacific Ocean in 19 IPCC AR4 Coupled General Circulation Models
This study examines systematic biases in sea surface temperature (SST) under the stratus cloud deck in the southeast Pacific Ocean and upper-ocean processes relevant to the SST biases in 19 coupled general circulation models (CGCMs) participating ...
Yangxing Zheng; Toshiaki Shinoda; Jia-Lin Lin; George N. Kiladis
Application of a Lightning Data Assimilation Technique in the WRF-ARW Model at Cloud-Resolving Scales for the Tornado Outbreak of 24 May 2011
This study presents the assimilation of total lightning data to help initiate convection at cloud-resolving scales within a numerical weather prediction model. The test case is the 24 May 2011 Oklahoma tornado outbreak, which was characterized by ...
Alexandre O. Fierro; Edward R. Mansell; Conrad L. Ziegler; Donald R. MacGorman
The Angular Distribution of UV-B Sky Radiance under Cloudy Conditions: A Comparison of Measurements and Radiative Transfer Calculations Using a Fractal Cloud Model
In recent years, global warming concerns have focused attention on cloud radiative forcing and its accurate encapsulation in radiative transfer measurement and modeling programs. At present, this process is constrained by the dynamic movement and ...
Christopher Kuchinke; Kurt Fienberg; Manuel Nunez
Surface Solar Radiation Flux and Cloud Radiative Forcing for the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP): A Satellite, Surface Observations, and Radiative Transfer Model Study
This study presents surface solar radiation flux and cloud radiative forcing results obtained by using a combination of satellite and surface observations interpreted by means of a simple plane-parallel radiative transfer model called 2001. This ...
Catherine Gautier; Martin Landsfeld
Research Highlights Sorted by Working Group
Working Group Working Group Aerosol Life Cycle | Cloud Life Cycle | Cloud-Aerosol-Precipitation Interactions | Aerosol | Cloud Modeling | Cloud Properties | Radiative Processes Aerosol Life Cycle 2013 Bhattacharya, A. Wildfires Lead to More Warming Than Climate Models Predict, a New Mexico Fire Study Reports ASR Fast, J. . Development and Validation of a Black Carbon Mixing State Resolved Three-Dimensional Model ARM ASR Gilles, M., Moffet, R. Spectro-microscopic Measurements of Carbonaceous Aerosol Aging in Central California ARM ASR Kafle, D. N., Coulter, R. L. Micropulse Lidar-Derived Aerosol Optical Depth Climatology at ARM Sites Worldwide ARM Keppel-Aleks, G. Determining the Future of CO2 Using an Earth System Model ARM Li, Z. A Mixed Bag of Aerosols over Northeastern China ARM
A PDF-Based Model for Boundary Layer Clouds. Part II: Model Results
A new single-column model for the cloudy boundary layer, described in a companion paper, is tested for a variety of regimes. To represent the subgrid-scale variability, the model uses a joint probability density function (PDF) of vertical ...
Jean-Christophe Golaz; Vincent E. Larson; William R. Cotton
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
Nonstationarity in multifactor models of discrete jump processes, memory and application to cloud modeling
) and in ocean (phase transitions between water and ice). Reasons for these intrinsic limi- tations of standard of nonstationary Markov model parameterization (J. Atmos. Sci., 66, 2059-2072, (2009)) (that are constrained
Krause, Rolf
CESM Atmosphere Model Working Group Meeting 1 3 February 2012
aerosol" CAM5 configuration 9:25 Xiaohong Liu Evaluating and constraining ice cloud parameterizations Measurements for Guiding Ice Nucleation, PSD and Morphology Parameterizations in CAM5 11:15 Chris Bretherton Thermodynamic Phase Parameterization Based on CALIPSO Observations on Climate Simulation #12;CAM, high
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
A PDF-Based Model for Boundary Layer Clouds. Part I: Method and Model Description
A new cloudy boundary layer single-column model is presented. It is designed to be flexible enough to represent a variety of cloudiness regimes�such as cumulus, stratocumulus, and clear regimes�without the need for case-specific adjustments. The ...
Accounting for Unresolved Clouds in a 1D Infrared Radiative Transfer Model. Part I: Solution for Radiative Transfer, Including Cloud Scattering and Overlap
Various aspects of infrared radiative transfer through clouds are investigated. First, three solutions to the IR radiative transfer equation are presented and assessed, each corresponding to a different approximation for the Planck function. It ...
J. Li
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
Use of Cloud Model Microphysics for Passive Microwave-Based Precipitation Retrieval: Significance of Consistency between Model and Measurement Manifolds
Precipitation estimation from passive microwave radiometry based on physically based profile retrieval algorithms must be aided by a microphysical generator providing structure information on the lower portions of the cloud, consistent with the ...
Giulia Panegrossi; Stefano Dietrich; Frank S. Marzano; Alberto Mugnai; Eric A. Smith; Xuwu Xiang; Gregory J. Tripoli; Pao K. Wang; J. P. V. Poiares Baptista
Forecasting of Chaotic Cloud Absorption Time Series for Meteorological and Plume Dispersion Modeling
A nonlinear forecasting method based on the reconstruction of a chaotic strange attractor from about 1.5 years of cloud absorption data obtained from half-hourly Meteosat infrared images was used to predict the behavior of the time series 24 h in ...
V. P�rez-Mu�uzuri
Radiative Transfer to Space through a Precipitating Cloud at Multiple Microwave Frequencies. Part I: Model Description
In a two-part study we investigate the impact of time-dependent cloud microphysical structure on the transfer to space of passive microwave radiation at several frequencies across the EHF and lower SHF portions of the microwave spectrum in order ...
Alberto Mugnai; Eric A. Smith
Testing the Fixed Anvil Temperature Hypothesis in a Cloud-Resolving Model
Using cloud-resolving simulations of tropical radiative�convective equilibrium, it is shown that the anvil temperature changes by less than 0.5 K with a 2-K change in SST, lending support to the fixed anvil temperature (FAT) hypothesis. The ...
Zhiming Kuang; Dennis L. Hartmann
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
Cloud computing: Its history of development, modern state, and future considerations
In this article, the author describes the history of the development, modern state, and future considerations of cloud (diffused) computing as one of the modern innovative technologies. The models of cloud computing and its advantages and disadvantages ... Keywords: cloud computing, cloud data processing, community cloud, information technology, innovative technology, operating system, private cloud, public cloud
V. V. Arutyunov
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.
Infinite cloud model of electrification by the precipitation mechanism in a possible rainout situation. Interim report, 14 January 1976--30 July 1977
This report examines the extent to which the ionization associated with a radioactive aerosol will limit electric field growth in a thundercloud. Favored mechanisms for thundercloud electrification, called precipitation mechanisms, involve charge separation in collisions between falling hydrometeors and cloud droplets followed by separation of the resulting charged objects as the hydrometeors fall through the cloud and the droplets move with the updraft. We have extended a simple, infinite-cloud, precipitation-mechanism model to include effects due to the presence of radioactive aerosol particles. These effects involve ion generation, convection currents due to motions of ions and charged aerosol particles, and collection of ions and aerosol particles by hydrometeors and cloud droplets.
Spangler, J.D.
Role of Modified Chaplygin Gas as a Dark Energy Model in Collapsing Spherically Symmetric Cloud
In this work, gravitational collapse of a spherical cloud, consists of both dark matter and dark energy in the form of modified Chaplygin gas is studied. It is found that dark energy alone in the form of modified Chaplygin gas forms black hole. Also when both components of the fluid are present then the collapse favors the formation of black hole in cases the dark energy dominates over dark matter. The conclusion is totally opposite to the usually known results.
Ujjal Debnath; Subenoy Chakraborty
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...
Central and Satellite Colors in Galaxy Groups: A Comparison of the Halo Model and SDSS Group Catalogs
Current analytic and semi-analytic dark matter halo models distinguish between the central galaxy in a halo and the satellite galaxies in halo substructures. It is expected that galaxy properties are correlated with host halo mass, and that central galaxies tend to be the most luminous, massive, and reddest galaxies in halos while the satellites around them are fainter and bluer. Using a recent halo-model description of the color dependence of galaxy clustering (Skibba & Sheth 2008), we investigate the colors of central and satellite galaxies predicted by the model and compare them to those of two galaxy group catalogs constructed from the Sloan Digital Sky Survey (Yang et al. 2007, Berlind et al. 2006a). In the model, the environmental dependence of galaxy color is determined by that of halo mass, and the predicted color mark correlations were shown to be consistent with SDSS measurements. The model assumes that satellites tend to follow a color-magnitude sequence that approaches the red sequence at bright luminosities; the model�s success suggests that bright satellites tend to be �red and dead � while the star formation in fainter ones is in the process of being quenched. In both the model and the SDSS group catalogs, we find that at fixed luminosity or stellar mass, central galaxies tend to be bluer than satellites. In contrast, at fixed group richness or halo mass, central galaxies tend to be redder than satellites, and galaxy colors become redder with increasing mass. We also compare the central and satellite galaxy color distributions, as a function of luminosity and as a function of richness, in the model and in the two group catalogs. Except for faint galaxies and small groups, the model and both group catalogs are in very good agreement.
Ramin A. Skibba
SPACE4CLOUD: a tool for system performance and costevaluation of cloud systems
Cloud Computing is assuming a relevant role in the world of web applications and web services. Cloud technologies allow to build dynamic systems which are able to adapt their performance to workload fluctuations delegating to the Cloud Provider the intensive ... Keywords: cloud computing, model-driven software development, performance prediction
Davide Franceschelli; Danilo Ardagna; Michele Ciavotta; Elisabetta Di Nitto
Sensitivity of Boundary-layer and Deep Convective Cloud Simulations...
convective clouds using a cloud resolving model (CRM). A CRM usually uses a vertical grid spacing less than 100 m to simulate boundary layer clouds such as shallow cumuli and...
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
On the Relationship between Sulfate and Cloud Droplet Number Concentrations
Comparisons are drawn between the aerosol cloud microphysical theory implicit in the modeling of Kaufman et al. and the cloud droplet and cloud water sulfate concentrations of Leaitch et al. for the purpose of helping to understand the effect of ...
W. R. Leaitch; G. A. Isaac
Defining Marine Boundary Layer Clouds with a Prognostic Scheme
A prognostic cloud scheme is described based on Tiedtke's cloud parameterization for large-scale meteorological models, which uses prognostic equations for both mean liquid water content and cloud fraction. The present work parameterizes the ...
Shouping Wang
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
How to Build a Cosmic-Ray Cloud Chamber How to Build a Cosmic-Ray Cloud Chamber October 2008, Version 1.4 * QuarkNet version. Fermi National Accelerator Laboratory. * Instructions written by Jeremy Paschke, York High School and Anne Mary Teichert, Fermilab. * Model initially designed and built by Robert Peterson, Fermilab. If you have further questions, or improvements of your own you would like to share with the QuarkNet group, please contact: Jeremy Paschke, York High School Physics Instructor (firstname.lastname@example.com), or Bob Peterson, Fermilab Education Specialist, (email@example.com). Justification: Showing your class a working cloud chamber is one of the best ways to generate student interest in modern physics. The cloud chamber described below will display natural background radiation (muons generated by
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
Comparison of 30-Day Integrations with and without Cloud-Radiation Interaction
A parameterization package for cloud-radiation interaction is incorporated into a spectral general circulation model (GCM). Fractional cloud amount is predicted quasi-empirically; cloud optical depth is specified for warm clouds and anvil cirrus, ...
C. T. Gordon
Observations of the Interaction between Cumulus Clouds and Warm Stratocumulus Clouds in the Marine Boundary Layer during ASTEX
Decoupling of the marine boundary layer beneath stratocumulus clouds and the formation of cumulus clouds at the top of a surface-based mixed layer (SML) have frequently been observed and modeled. When such cumulus clouds penetrate the overlying ...
G. M. Martin; D. W. Johnson; D. P. Rogers; P. R. Jonas; P. Minnis; D. A. Hegg
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
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
Global Cloud Climatologies: A Historical Review
Accurate global cloud information is required for many climate studies, particularly for validation of climate model simulations. This paper reviews the cloud climatologies currently available, identifying and attempting to explain the ...
N. A. Hughes
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
Aquaplanets, Climate Sensitivity, and Low Clouds
Cloud effects have repeatedly been pointed out as the leading source of uncertainty in projections of future climate, yet clouds remain poorly understood and simulated in climate models. Aquaplanets provide a simplified framework for comparing ...
Brian Medeiros; Bjorn Stevens; Isaac M. Held; Ming Zhao; David L. Williamson; Jerry G. Olson; Christopher S. Bretherton
The Surface Downwelling Solar Radiation Surplus over the Southern Ocean in the Met Office Model: The Role of Midlatitude Cyclone Clouds
The authors study the role of clouds in the persistent bias of surface downwelling shortwave radiation (SDSR) in the Southern Ocean in the atmosphere-only version of the Met Office model. The reduction of this bias in the atmosphere-only version ...
A. Bodas-Salcedo; K. D. Williams; P. R. Field; A. P. Lock
Response of ice and liquid water paths of tropical cyclones to global warming simulated by a global nonhydrostatic model with explicit cloud microphysics
Cloud feedback plays a key role in the future climate projection. Using global non-hydrostatic model (GNHM) simulation data for a present-day (CTL) and a warmer (GW) experiment, we estimate the contribution of tropical cyclones (TC) to ice/liquid ...
Yohei Yamada; Masaki Satoh
Enabling cloud interoperability with COMPSs
The advent of Cloud computing has given to researchers the ability to access resources that satisfy their growing needs, which could not be satisfied by traditional computing resources such as PCs and locally managed clusters. On the other side, such ... Keywords: PaaS, cloud computing, data mining, parallel programming models
Fabrizio Marozzo; Francesc Lordan; Roger Rafanell; Daniele Lezzi; Domenico Talia; Rosa M. Badia
A Theoretical Method for Computing Vertical Distributions of Acidity and Sulfate Production within Cumulus Clouds
An aqueous chemistry model has been combined with an entraining cumulus cloud model to predict vertical distributions of pH (=?log10[H+]) within a cloud. The cloud model predicts vertical variations of temperature, pressure, entrainment and ...
Chris J. Walcek; Gregory R. Taylor
Ice in Clouds Experiment�Layer Clouds. Part II: Testing Characteristics of Heterogeneous Ice Formation in Lee Wave Clouds
Heterogeneous ice nucleation is a source of uncertainty in models that represent ice clouds. The primary goal of the Ice in Clouds Experiment�Layer Clouds (ICE-L) field campaign was to determine if a link can be demonstrated between ice ...
P. R. Field; A. J. Heymsfield; B. J. Shipway; P. J. DeMott; K. A. Pratt; D. C. Rogers; J. Stith; K. A. Prather
Changing the Climate Sensitivity of an Atmospheric General Circulation Model through Cloud Radiative Adjustment
Conducting probabilistic climate projections with a particular climate model requires the ability to vary the model�s characteristics, such as its climate sensitivity. In this study, the authors implement and validate a method to change the ...
Andrei P. Sokolov; Erwan Monier
CMIP3 Subtropical Stratocumulus Cloud Feedback Interpreted through a Mixed-Layer Model
Large-scale conditions over subtropical marine stratocumulus areas are extracted from global climate models (GCMs) participating in phase 3 of the Coupled Model Intercomparison Project (CMIP3) and used to drive an atmospheric mixed-layer model (...
Peter M. Caldwell; Yunyan Zhang; Stephen A. Klein
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)
Multiscale Interactions in the Life Cycle of a Tropical Cyclone Simulated in a Global Cloud-System-Resolving Model. Part I: Large-Scale and Storm-Scale Evolutions
The Nonhydrostatic Icosahedral Atmospheric Model (NICAM), a global cloud-system-resolving model, successfully simulated the life cycle of Tropical Storm Isobel that formed over the Timor Sea in the austral summer of 2006. The multiscale ...
Efficient Mushroom Cloud Simulation on GPU
In this paper, we present a method to simulate the Mushroom Cloud efficient on GPU using advanced particle system, and our particle system is a state-preserving simulation system. We provide the visual-only model of Mushroom Cloud and we divide the Mushroom ... Keywords: Floating Point Textures, GPU (Graphics Processing Unit), Mushroom Cloud simulation, particle system, state-preserving simulation
Xingquan Cai; Jinhong Li; Zhitong Su
Cloud Computing: Exploring the scope
Cloud computing refers a paradigm shift to overall IT solutions while raising the accessibility, scalability and effectiveness through its enabling technologies. However, migrated cloud platforms and services cost benefits as well as performances are neither clear nor summarized. Globalization and the recessionary economic times have not only raised the bar of a better IT delivery models but also have given access to technology enabled services via internet. Cloud computing has vast potential in terms of lean Retail methodologies that can minimize the operational cost by using the third party based IT capabilities, as a service. It will not only increase the ROI but will also help in lowering the total cost of ownership. In this paper we have tried to compare the cloud computing cost benefits with the actual premise cost which an organization incurs normally. However, in spite of the cost benefits, many IT professional believe that the latest model i.e. "cloud computing" has risks and security concerns. This ...
Pandey, Abhinav; Tandon, Ankit; Maurya, Brajesh Kr; Kushwaha, Upendra
BALTEX BRIDGE cloud liquid water network project: CLIWA-NET
3/2008 3/2008 ARM-08 Photo courtesy Bjorn Stevens ARM-GEWEX Cloud System Studies (GCSS) Collaborations: Past-Present-Future A. Pier Siebesma firstname.lastname@example.com chair GCCS KNMI, De Bilt, The Netherlands Technical University Delft Multiscale Physics Group Delft, The Netherlands 4/3/2008 ARM-08 Topics Introduction to GCSS activities Examples and Results for parameterization development in the past. (has it made a difference?) Past and Present Collaborations and results between ARM and GCSS The Future: How can we do better? 4/3/2008 ARM-08 Objective of GCSS GCSS is developing improved parameterizations of cloud systems for climate models and numerical weather prediction models by improving our understanding of the physical processes for all the climate relevant cloud types 4/3/2008 ARM-08
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
Temporal and Vertical Distribution of Acidity and Ionic Composition in Clouds: Comparison between Modeling Results and Observations
Cyclic temporal variations of pH and ionic concentration in sampled clouds which traversed the Mt. Mitchell State Park site (35�44?05?N, 82�17?15?W, 2006 m MSL) during the summers of 1986, 1987 and 1988 are reported. These clouds typically had a ...
T. P. DeFelice; V. K. Saxena
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
Prediction of convective morphology in near-cloud permitting WRF model simulations
The Weather Research and Forecasting (WRF) model�s ability to forecast convective morphological evolution is examined for 37 convective systems. The simulations used Thompson microphysics with 3-km horizontal grid spacing. Ten convective mode ...
Darren V. Snively; William A. Gallus; Jr.
The Estimation of Hourly Global Solar Radiation Using a Cloud Cover Model Developed at Blytheville, Arkansas
The lack of a comprehensive solar radiation monitoring network throughout the United States has led to extensive modeling. Some of the models use a measured component, usually the global solar radiation, to predict the other components, direct ...
W. D. Turner; Abdulaziz Mujahid
A New Cloud Physics Parameterization in a Large-Eddy Simulation Model of Marine Stratocumulus
A new bulk microphysical parameterization for large-eddy simulation (LES) models of the stratocumulus-topped boundary layer has been developed using an explicit (drop spectrum resolving) microphysical model as a data source and benchmark for ...
Marat Khairoutdinov; Yefim Kogan
Tests of an Adjoint Mesoscale Model with Explicit Moist Physics on the Cloud Scale
An adjoint modeling system based upon the Naval Research Laboratory�s Coupled Ocean�Atmosphere Mesoscale Prediction System�s atmospheric component has been developed. The system includes the adjoint model of the explicit moist physics ...
Clark Amerault; Xiaolei Zou; James Doyle
On the Dynamics of Hawaiian Cloud Bands: Comparison of Model Results with Observations and Island Climatology
This paper presents a detailed comparison study of three-dimensional model results with an aircraft wind field mapping for the island of Hawaii. Model runs were initialized using an aircraft sounding from 1 August 1985, and detailed predictions ...
Roy M. Rasmussen; Piotr Smolarkiewicz; John Warner
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.
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
Cloud Cover and Climate Sensitivity
This study discusses how the sensitivity of climate may be affected by the variation of cloud cover based on the results from numerical experiments with a highly simplified, three-dimensional model of the atmospheric general circulation. The ...
Richard T. Wetherald; Syukuro Manabe
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
Convectively Generated Gravity Waves and Their Effect on the Cloud Environment
This study uses a two-dimensional cloud-resolving model to examine how convectively generated gravity waves modify the environment of an isolated convective cloud. The model is initialized with an idealized sounding, and the cloud is initiated by ...
Todd P. Lane; Michael J. Reeder
Modelling symmetry of activity as an indicator of collocated group collaboration
There are many contexts where it would be helpful to model the collaboration of a group. In learning settings, this is important for classroom teachers and for students learning collaboration skills. Our approach exploits the digital and audio footprints ... Keywords: clustering, collaborative learning, collocated collaboration, group modelling, groupware, tabletop
Roberto Martinez; Judy Kay; James R. Wallace; Kalina Yacef
Models of social groups in blogosphere based on information about comment addressees and sentiments
This work concerns the analysis of number, sizes and other characteristics of groups identified in the blogosphere using a set of models identifying social relations. These models differ regarding identification of social relations, influenced by methods ... Keywords: blogosphere, groups, sentiment, social network analysis
Bogdan Gliwa; Jaros?aw Ko?lak; Anna Zygmunt; Krzysztof Cetnarowicz
A high-resolution, cloud-assimilating numerical weather prediction model for solar irradiance forecasting
Mathiesen, Patrick; Collier, Craig; Kleissl, Jan
Role of Data Communications in Hybrid Cloud Costs
Rapid adoption of cloud services in recent years has been driven by multiple factors, such as faster time-to-market and improved scalability enabled by public cloud infrastructure. Hybrid clouds, combining the in-house capacities with on-demand capacity ... Keywords: hybrid cloud, cost model, data communications cost
Oleksiy Mazhelis; Pasi Tyrvainen
Common Information Model (CIM) Users Group Spring 2011 Meeting Summary
A clear picture was painted by multiple presentations given by a variety of speakers: the Common Information Model (CIM) has an essential role to play in Smart Grid around the world. More than 10 presentations focused on utility efforts: some projects are in the design stage but many are in the deployment stage with utilities developing CIM expertise and with the CIM facilitating information sharing. A surprising number of countries are viewing the CIM as a basis for national standardization efforts and ...
Scale Dependence of Solar Heating Rates in Convective Cloud Systems with Implications to General Circulation Models
The authors examine 3D solar radiative heating rates within tropical convective�cirrus systems to identify the scales that contribute significantly to the spatial average over a climate model�s grid cell (i.e., its grid mean), and determine their ...
A. M. Vogelmann; V. Ramanathan; I. A. Podgorny
Predicting Cloud-to-Ground and Intracloud Lightning in Weather Forecast Models
A new prognostic, spatially and temporally dependent variable is introduced to the Weather Research and Forecasting Model (WRF). This variable is called the potential electrical energy (Ep). It was used to predict the dynamic contribution of the ...
Barry H. Lynn; Yoav Yair; Colin Price; Guy Kelman; Adam J. Clark
LMODEL: A Satellite Precipitation Methodology Using Cloud Development Modeling. Part II: Validation
A new satellite-based rainfall monitoring algorithm that integrates the strengths of both low Earth-orbiting (LEO) and geostationary Earth-orbiting (GEO) satellite information has been developed. The Lagrangian Model (LMODEL) algorithm combines a ...
Kuo-lin Hsu; Tim Bellerby; S. Sorooshian
Impact of Changes to the Radiation Transfer Parameterizations Plus Cloud Optical. Properties in the ECMWF Model
A new radiation package, shown to correct most of the systematic errors of the operational ECMWF radiation scheme, has been extensively tested in the ECMWF forecast model. Improvements in the clear-sky fluxes and radiative heating/cooling rate ...
Jean-Jacques Morcrette
Improvements in Shortwave Bulk Scattering and Absorption Models for the Remote Sensing of Ice Clouds
This study summarizes recent improvements in the development of bulk scattering/absorption models at solar wavelengths. The approach combines microphysical measurements from various field campaigns with single-scattering properties for nine habits ...
Bryan A. Baum; Ping Yang; Andrew J. Heymsfield; Carl G. Schmitt; Yu Xie; Aaron Bansemer; Yong-Xiang Hu; Zhibo Zhang
Estimation and Model Validation of Surface Solar Radiation and Cloud Radiative Forcing Using TOGA COARE Measurements
The Tropical Ocean and Global Atmosphere Coupled Ocean�Atmosphere Response Experiment (TOGA COARE) radiation measurements in the western Pacific warm pool are used to estimate surface solar radiation budgets and to validate radiation model ...
Ming-Dah Chou; Wenzhong Zhao
Cloud and Precipitation Parameterizations in Modeling and Variational Data Assimilation: A Review
This paper first reviews the current status, issues, and limitations of the parameterizations of atmospheric large-scale and convective moist processes that are used in numerical weather prediction and climate general circulation models. Both ...
Philippe Lopez
Cloud shading direct solar radiation model for the Crosbyton Solar Power Project
The CSPP was initiated to study the feasibility of using hemispheric bowl solar collectors for power generation. A non-spectral direct solar radiation (DSR) model was developed to aid in determining whether there exists a preferred spacing of these solar collectors based solely on meteorological considerations. The DSR model is applicable to the Northern Hemisphere and, with a few adjustments, to the Southern Hemisphere. The DSR model considers the reduction of direct insolation through the atmosphere due to Rayleigh scattering, uniformly mixed gases, ozone, precipitable water, and aerosols. It incorporates geographical information along with temperature, dew point, barometric pressure, and visibility data, updated every 15 minutes. This clear sky DSR model was verified against actual direct insolation data.
Peterson, R.E.; Smalley, D.J.
Isentropic modeling of a cirrus cloud event observed in the midlatitude upper troposphere and lower stratosphere
´so-e´chelle de l'Ozone Stratosphe´rique par Advection (MIMOSA) model to take into account the three phases for fall speeds around 1 cm/s and gives ice water content around 34 mg/m3 . Fall speed is also a critical parameter, and a better parameterization with altitude or other atmospheric conditions in the modeling
Brogniez, Hélène
Magellan: experiences from a Science Cloud
computing for science at the Argonne Leadership Computinghow the cloud computing business Argonne NationalLab Argonne, IL model can be used to serve the needs of mid-
Ramakrishnan, Lavanya
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...
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
On the Usage of Spectral and Broadband Satellite Instrument Measurements to Differentiate Climate Models with Different Cloud Feedback Strengths
Top-of-atmosphere radiometric signals associated with different high- and low-cloud�radiative feedbacks have been examined through the use of an observing system simulation experiment (OSSE). The OSSE simulates variations in the spectrally ...
Daniel R. Feldman; Daniel M. Coleman; William D. Collins
An Artificial Neural Network model to reduce false alarms in satellite precipitation products using MODIS and CloudSat observations
The Moderate Resolution Imaging Spectro-radiometer (MODIS) instrument aboard the NASA Earth Observing System (EOS) Aqua and Terra platform with 36 spectral bands provides valuable information about cloud microphysical characteristics and therefore ...
Nasrin Nasrollahi; Kuolin Hsu; Soroosh Sorooshian
Mixing Layer Formation near the Tropopause Due to Gravity Wave�Critical Level Interactions in a Cloud-Resolving Model
A plausible mechanism for the formation of mixing layers in the lower stratosphere above regions of tropical convection is demonstrated numerically using high-resolution, two-dimensional (2D), anelastic, nonlinear, cloud-resolving simulations. ...
Mohamed Moustaoui; Binson Joseph; Hector Teitelbaum
Top-of-atmosphere radiometric signals associated with different high- and low-cloud radiative feedbacks have been examined through the use of an observing system simulation experiment (OSSE). The OSSE simulates variations in the spectrally ...
The Impact of Clouds on the Shortwave Radiation Budget of the Surface-Atmosphere System: Interfacing Measurements and Models
Two datasets have been combined to demonstrate how the availability of more comprehensive datasets could serve to elucidate the shortwave radiative impact of clouds on both the atmospheric column and the surface. These datasets consist of two ...
Robert D. Cess; Seth Nemesure; Ellsworth G. Dutton; John J. Deluisi; Gerald L. Potter; Jean-Jacques Morcrette
A Study of the Aerosol Effect on a Cloud Field with Simultaneous Use of GCM Modeling and Satellite Observation
The indirect effect of aerosols was simulated by a GCM for nonconvective water clouds and was compared with remote sensing results from the Advanced Very High Resolution Radiometer (AVHRR) satellite-borne sensor for January, April, July, and ...
Kentaroh Suzuki; Teruyuki Nakajima; Atusi Numaguti; Toshihiko Takemura; Kazuaki Kawamoto; Akiko Higurashi
A Local Ensemble Prediction System for Fog and Low Clouds: Construction, Bayesian Model Averaging Calibration, and Validation
At main international airports, air traffic safety and economic issues related to poor visibility conditions are crucial. Meteorologists face the challenge of supplying airport authorities with accurate forecasts of fog and cloud ceiling. These ...
Stevie Roquelaure; Thierry Bergot
Similarity of Deep Continental Cumulus Convection as Revealed by a Three-Dimensional Cloud-Resolving Model
A three-dimensional cloud-resolving simulation of midlatitude continental convection during the Atmospheric Radiation Measurement (ARM) program summer 1997 intensive observation period (IOP) is used to study the similarity of several second and ...
Marat F. Khairoutdinov; David A. Randall
Investigations of cloud altering effects of atmospheric aerosols using a new mixed Eulerian-Lagrangian aerosol model
Industry, urban development, and other anthropogenic influences have substantially altered the composition and size-distribution of atmospheric aerosol particles over the last century. This, in turn, has altered cloud ...
Steele, Henry Donnan, 1974-
A New Double-Moment Microphysics Parameterization for Application in Cloud and Climate Models. Part I: Description
A new double-moment bulk microphysics scheme predicting the number concentrations and mixing ratios of four hydrometeor species (droplets, cloud ice, rain, snow) is described. New physically based parameterizations are developed for simulating ...
H. Morrison; J. A. Curry; V. I. Khvorostyanov
Improvement of modelling capabilities for assessing urban contamination : The EMRAS Urban Remediation Working Group.
The Urban Remediation Working Group of the International Atomic Energy Agency's Environmental Modeling for Radiation Safety (EMRAS) programme was established to improve modeling and assessment capabilities for radioactively contaminated urban situations, including the effects of countermeasures. An example of the Working Group's activities is an exercise based on Chernobyl fallout data in Ukraine, which has provided an opportunity to compare predictions among several models and with available measurements, to discuss reasons for discrepancies, and to identify areas where additional information would be helpful.
Thiessen, K. M.; Batandjieva, B.; Andersson, K. G.; Arkhipov, A.; Charnock, T. W.; Gallay, F.; Gaschak, S.; Golikov, V.; Hwang, W. T.; Kaiser, J. C.; Kamboj, S.; Steiner, M.; Tomas, J.; Trifunovic, D.; Yu, C.; Ziemer, R. L.; Zlobenko, B.; Environmental Science Division; SENES Oak Ridge; IAEA; Riso National Lab.; Chernobyl Center for Nuclear Safety; Health Protection Agency; IRSN; Inst. of Radiation Hygene of the Ministry of Public Health, Russian Federation; KAERI, Republic of Korea; GSF, Germany; BfS, Germany; CPHR, Cuba; State Office for Radiation Protection, Croatia; AECL, Canada; National Academy of Science, Ukraine
Carbon Dioxide and Climate. The Impact of Cloud Parameterization
The importance of the representation of cloud in a general circulation model is investigated by utilizing four different parameterization schemes for layer cloud in a low-resolution version of the general circulation model at the Hadley Centre ...
C. A. Senior; J. F. B. Mitchell
Windowed and Wavelet Analysis of Marine Stratocumulus Cloud Inhomogeneity
To improve radiative transfer calculations for inhomogeneous clouds, a consistent means of modeling inhomogeneity is needed. One current method of modeling cloud inhomogeneity is through the use of fractal parameters. This method is based on the ...
Steven M. Gollmer; Harshvardhan; Robert F. Cahalan; Jack B. Snider
Evaporation and condensation of spherical interstellar clouds. Self-consistent models with saturated heat conduction and cooling
Shortened version: The fate of IS clouds embedded in a hot tenuous medium depends on whether the clouds suffer from evaporation or whether material condensates onto them. Analytical solutions for the rate of evaporative mass loss from an isolated spherical cloud embedded in a hot tenuous gas are deduced by Cowie & McKee (1977). In order to test the validity of the analytical results for more realistic IS conditions the full hydrodynamical equations must be treated. Therefore, 2D numerical simulations of the evolution of IS clouds %are performed with different internal density structures and surrounded by a hot plasma reservoir. Self-gravity, interstellar heating and cooling effects and heat conduction by electrons are added. Classical thermal conductivity of a fully ionized hydrogen plasma and saturated heat flux are considered. Using pure hydrodynamics and classical heat flux we can reproduce the analytical results. Heat flux saturation reduces the evaporation rate by one order of magnitude below the analytical value. The evolution changes totally for more realistic conditions when interstellar heating and cooling effects stabilize the self-gravity. Evaporation then turns into condensation, because the additional energy by heat conduction can be transported away from the interface and radiated off efficiently from the cloud's inner parts. I.e. that the saturated heat flux consideration is inevitable for IS clouds embedded in hot tenuous gas. Various consequences are discussed in the paper.
W. Vieser; G. Hensler
Angular Distribution Models for Top-of-Atmosphere Radiative Flux Estimation from the Clouds and the Earth's Radiant Energy System Instrument on the Tropical Rainfall Measuring Mission Satellite. Part II: Validation
Top-of-atmosphere (TOA) radiative fluxes from the Clouds and the Earth's Radiant Energy System (CERES) are estimated from empirical angular distribution models (ADMs) that convert instantaneous radiance measurements to TOA fluxes. This paper ...
Norman G. Loeb; Konstantin Loukachine; Natividad Manalo-Smith; Bruce A. Wielicki; David F. Young
Angular Distribution Models for Top-of-Atmosphere Radiative Flux Estimation from the Clouds and the Earth�s Radiant Energy System Instrument on the Terra Satellite. Part II: Validation
Errors in top-of-atmosphere (TOA) radiative fluxes from the Clouds and the Earth�s Radiant Energy System (CERES) instrument due to uncertainties in radiance-to-flux conversion from CERES Terra angular distribution models (ADMs) are evaluated ...
Norman G. Loeb; Seiji Kato; Konstantin Loukachine; Natividad Manalo-Smith; David R. Doelling
A Large-Droplet Mode and Prognostic Number Concentration of Cloud Droplets in the Colorado State University Regional Atmospheric Modeling System (RAMS). Part I: Module Descriptions and Supercell Test Simulations
The microphysics module of the version of the Regional Atmospheric Modeling System (RAMS) maintained at Colorado State University has undergone a series of improvements, including the addition of a large-cloud-droplet mode from 40 to 80 ?m in ...
Cloud and Precipitation Parameterization in a Meso-Gamma-Scale Operational Weather Prediction Model
The paper assesses the difficulties of running an operational NWP model in the resolution range of 3�8 km. In this case, deep convection cells are neither much smaller than the grid box as assumed by most parameterization schemes, nor completely ...
Luc Gerard; Jean-Marcel Piriou; Radmila Bro�kov�; Jean-Fran�ois Geleyn; Doina Banciu
Model Clouds as Seen from Space: Comparison with Geostationary Imagery in the 11-?m Window Channel
A monitoring of the European Centre for Medium-Range Weather Forecasts (ECMWF) model with the Meteosat infrared window channel during December 2000 is presented. The Meteosat images are simulated every 3 h during the 31 days of the month from the ...
F. Chevallier; G. Kelly
Measurements and modeling of the effect of convective clouds on the upper tropospheric moisture budget
The goal of this study is to determine the upper tropospheric moisture budget associated with convective events, and in particular to extend process models to higher altitudes than have been achieved previously. Although upper tropospheric moisture concentrations are several orders of magnitude lower than those near the surface, upper tropospheric moisture exerts an important influence on climate. On a per-molecule basis, greenhouse absorption due to water vapor is about one hundred times more effective at high altitudes than at low altitudes. Several one-dimensional radiative convective models have been used to demonstrate the importance of upper tropospheric moisture on climate. These models show that for a given fractional increase in water vapor at a given altitude the response or change in surface temperature is qualitatively the same. At present, considerable controversy exists over the nature of the vertical redistribution of water vapor in a changing climate, and particularly the distribution of water vapor in the upper troposphere. Lacking suitable data, this controversy is also reflected in the cumulus parameterization schemes that are currently used in models. Understanding upper tropospheric moistening processes are therefore of prime importance in addressing the water vapor feedback question.
Bisson, S.E.; Goldsmith, J.E.M. [Sandia National Labs., Livermore, CA (United States); Del Genio, A.D. [National Aeronautics and Space Administration, New York, NY (United States). Goddard Inst. for Space Studies
Convective Systems over the South China Sea: Cloud-Resolving Model Simulations
The two-dimensional version of the Goddard Cumulus Ensemble (GCE) model is used to simulate two South China Sea Monsoon Experiment (SCSMEX) convective periods [18�26 May (prior to and during the monsoon onset) and 2�11 June (after the onset of ...
W-K. Tao; C-L. Shie; J. Simpson; S. Braun; R. H. Johnson; P. E. Ciesielski
SCM Working Group
cloud microphysical parameterizations cloud microphysical parameterizations with SCM, CAPT and M-PACE observations X. Liu (PNNL) S. Xie, J. Boyle, S. Klein (LLNL) S. J. Ghan (PNNL) H. Morrison, A. Gettelman (NCAR) Goal: Improve Climate Model Parameterizations Tools: single column models (SCM) and DOE CCPP-ARM Parameterization Testbed (CAPT) (LLNL CAPT team) ARM measurements provide unique data for model evaluation and guidance for parameterization improvement Motivations Cloud microphysics in mixed-phase clouds has a significant impact on cloud radiative forcing, precipitation formation, etc. The treatment of mixed-phase clouds in most current climate models is often oversimplified Liquid/ice partitioning according to a temperature dependent function; Neglect ice nucleation and Bergeron-Findeisen
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
Extracting multilayered Communities of Interest from semantic user profiles: Application to group modeling and hybrid recommendations
A Community of Interest is a specific type of Community of Practice. It is formed by a group of individuals who share a common interest or passion. These people exchange ideas and thoughts about the given passion. However, they are often not aware of ... Keywords: Communities of Interest, Communities of Practice, Content-based collaborative filtering, Group modeling, Ontology, User profile
Iv�n Cantador; Pablo Castells
Incorporation of a Cloud Simulation into a Flight Mission Rehearsal System: Prototype Demonstration
One environmental parameter that has a large impact on aircraft missions for the U.S. military is clouds. This article describes an initial attempt to incorporate physically consistent clouds into a flight mission rehearsal system. A cloud model ...
Louis Hembree; Sam Brand; William C. Mayse; Maureen Cianciolo; Brian Soderberg
A Methodology for Measuring Cirrus Cloud Visible-to-Infrared Spectral Optical Depth Ratios
Knowledge of cirrus cloud optical depths is necessary to understand the earth�s current climate and to model the cloud radiation impact on future climate. Cirrus clouds, depending on the ratio of their shortwave �visible� to longwave �infrared� ...
Daniel H. DeSlover; William L. Smith; Paivi K. Piironen; Edwin W. Eloranta
Some Surprising Results from Simulated Seeding of Stratiform-Type Clouds
Studies have been conducted to determine the cloud seeding potential of stratiform type clouds using a two-dimensional, time-dependent cloud model. An atmospheric sounding from Villanubla, Spain, in February 1980, was used to initialize the ...
Harold D. Orville; Richard D. Farley; John H. Hirsch
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
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
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...
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...
ARM - Field Campaign - Cloud IOP
govCampaignsCloud IOP govCampaignsCloud IOP Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Campaign : Cloud IOP 1998.04.27 - 1998.05.17 Lead Scientist : Gerald Mace For data sets, see below. Summary Monday, April 27, 1998 IOP Opening Activities: Heavy rain (nearly 2.5" since 12Z 4/26/98) at the central facility (CF) dominated the first day of the Cloud Physics/Single Column Model IOP and limited the daily activities. A 1430 GMT sonde launch commenced the 3-hour sonde launch schedule at the CF and 4 boundary facilities (BFs). Scientists/Instrumentation on Site: Citation: Has arrived and is located at the Ponca City Airport. No flights are currently planned. Flights are tentatively planned for stratus sampling when precipitation ends.
Clouds, Aerosols and Precipitation in
the Marine Boundary Layer (CAP-MBL) Graciosa Island, Azores, NE Atlantic Ocean Graciosa Island, Azores, NE Atlantic Ocean May 2009-December 2010 May 2009-December 2010 Rob Wood, University of Washington Rob Wood, University of Washington AMF Deployment Team Thanks to Mark Miller: AMF Site Scientist Mark Miller: AMF Site Scientist Kim Nitschke: AMF Site Manager CAP-MBL Proposal Team Importance of Low-Clouds for Climate Imperative that we understand the processes controlling the formation, maintenance and dissipation of low clouds in order to formation, maintenance and dissipation of low clouds in order to improve their representation in climate models. Which clouds matter for climate sensitivity? Cli t F db k
Relationship between Ice Water Path and Downward Longwave Radiation for Clouds Optically Thin in the Infrared: Observations and Model Calculations
A vertically pointing 3.2-cm radar is used to observe altostratus and cirrus clouds as they pass overhead. Radar reflectivities are used in combination with an empirical Zi-IWC (ice water content) relationship developed by Sassen (1987) to ...
Taneil Uttal; Sergey Y. Matrosov; Jack B. Snider; Robert A. Kropfli
Cloud Decoupling of the Surface and Planetary Radiative Budgets
We employ a one-dimensional radiative-convective equilibrium model with multiple cloud layers to demonstrate that the surface equilibrium temperature is highly sensitive to the vertical distribution of effective cloud base heights. It is also ...
Graeme L. Stephens; Peter J. Webster
Mesoscale Cloud State Estimation from Visible and Infrared Satellite Radiances
This study focuses on cloudy atmosphere state estimation from high-resolution visible and infrared satellite remote sensing measurements and a mesoscale model with explicit cloud prediction. The cloud state is defined as 3D spatially distributed ...
T. Vukicevic; T. Greenwald; M. Zupanski; D. Zupanski; T. Vonder Haar; A. S. Jones
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
Mass-Flux Budgets of Shallow Cumulus Clouds
The vertical transport by shallow nonprecipitating cumulus clouds of conserved variables, such as the total specific humidity or the liquid water potential temperature, can be well modeled by the mass-flux approach, in which the cloud field is ...
Stephan R. de Roode; Christopher S. Bretherton
Cloud computing models
Information Technology has always been considered a major pain point of enterprise organizations, from the perspectives of both cost and management. However, the information technology industry has experienced a dramatic ...
Gorelik, Eugene
Final Technical Report on Scaling Models of the Internal Variability of Clouds DoE Grant No. DE-FG02-04ER63773
The purpose of this proposal is to gain a better understanding of the space-time correlations of atmospheric fluctuations in clouds through application of methods from statistical physics to high resolution, continuous data sets of cloud observations available at the Department of Energy Atmospheric Radiation Measurement Program archive. In this report we present the accomplishments achieved during the four year period. Starting with the most recent one, we report on two break-throughs in our research that make the fourth year of the project exceptionally successful and markedly outperforming the objectives. The first break-through is on characterization of the structure of cirrus radiative properties at large, intermediate and small, generating cells scales by applying the Fokker-Planck equation method and other methods to ARM millimeter wavelength radar observations collected at the Southern Great Plains site. The second break-through is that we show that different characterizations of the cirrus radiative properties are obtained for different synoptic scale environments. We outline a stochastic approach to investigate the internal structure of radiative properties of cirrus clouds based on empirical modeling and draw conclusions about cirrus dynamical properties in the context of the synoptic environment. Results on the structure of cirrus dynamical properties are consistent with the structure of cirrus based on aircraft in situ measurements, with results from ground-based Raman lidar, and with results from model studies. These achievements would not have been possible without the accomplishments from the previous years on a number of problems that involve application of methods of analysis such as the Fokker-Planck equation approach, Tsallis nonextensive statistical mechanics, detrended fluctuation analysis, and others. These include stochastic analysis of neutrally stratified cirrus layers, internal variability and turbulence in cirrus, dynamical model and nonextensive statistical mechanics of liquid water path fluctuations, etc.
Ivanova, Kristinka
Simulation of Cloud Microphysical and Chemical Processes Using a Multicomponent Framework. Part II: Microphysical Evolution of a Wintertime Orographic Cloud
A detailed microphysical model is used to simulate the formation of wintertime orographic clouds in a two-dimensional domain under steady-state conditions. Mass contents and number concentrations of both liquid- and ice-phase cloud particles are ...
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 ...
Zhian Sun; Keith P. Shine
A Dynamical Model for the Orbit of the Andromeda Galaxy M31 and the Origin of the Local Group of Galaxies
We propose a new model for the origin and evolution of the Local Group of Galaxies (LGG) which naturally explains the formation of the Magellanic Clouds and their large orbital angular momenta around the Galaxy. The basic idea is that an off-center hydrodynamical collision occurred some 10 Gyr ago between the primordial gas-rich Andromeda galaxy and the similar Galaxy, and compressed the halo gas to form the LGG dwarf galaxies including the Magellanic Clouds. In this model, new-born dwarf galaxies can be expected to locate near the orbital plane of these two massive galaxies. In order to see the reality of this model, we reexamine the two-dimensional sky distribution of the LGG members and the Magellanic Stream, we confirm an earlier and widely-discussed idea that they align along two similar great circles, each with an angular width of $\\sim 30^{\\circ}$, and the planes of these circles are approximately normal to the line joining the present position of the sun and the Galactic center. Further we make a three-dimensional distribution map of these objects, and observe it from various directions. A well-defined plane of finite thickness is found, within which most of the member galaxies are confined, supporting the existence of the above circles on the sky. Thus we could determine the orbital elements of M31 relative to the Galaxy through reproducing the well-studied dynamics of the LMC and the SMC around the Galaxy. The expected proper motion of M31 is $(\\mu_l, \\mu_b)=(38 \\mu as/yr, -49 \\mu as/yr)$. Probable orbital motions of the other dwarfs are also determined, and the corresponding proper motion for each object is given to compare with observations in near future.
T. Sawa; M. Fujimoto
Goa, India Cyclic Lateral Response of Model Pile Groups in Clay
ABSTRACT: This paper presents the results of two-way cyclic lateral load tests conducted in the laboratory on the model pile groups embedded in soft clay. The purpose of this research work is to investigate the effects of spacing, number of cycles of loading and cyclic load level on the pile group behaviour in clay. A pneumatic system is used to simulate cyclic loading typical of wave loading. Similitude laws are adhered to in selecting the material and size of the model piles. Piles are instrumented so that bending moments developed along the piles can be calculated. The results emphasized highly nonlinear nature of load-deflection behaviour. Group interaction effect under cyclic lateral loading is predominant for groups with spacing to diameter ratio less than 7. It is found that the cyclic load levels exceeding 0.5 times of static ultimate capacity, produce large deflections of the pile group due to gaps developed at the pile-soil interface, remoulding of clay and subsequent reduction in the stiffness. The bending moments in the piles are increased with the number of cycles and the location of maximum bending moment shifted downwards along the length of the pile. Numerical analysis using software ? GROUP is also carried out for closely spaced pile groups subjected to static lateral loads and the results are compared with the experimental ones. 1
S. S. Ch; A. Boominathan; G. R. Dodagoudar
Eastern Pacific Emitted Aerosol Cloud Experiment
Aerosol�cloud�radiation interactions are widely held to be the largest single source of uncertainty in climate model projections of future radiative forcing due to increasing anthropogenic emissions. The underlying causes of this uncertainty among modeled ...
Lynn M. Russell; Armin Sorooshian; John H. Seinfeld; Bruce A. Albrecht; Athanasios Nenes; Lars Ahlm; Yi-Chun Chen; Matthew Coggon; Jill S. Craven; Richard C. Flagan; Amanda A. Frossard; Haflidi Jonsson; Eunsil Jung; Jack J. Lin; Andrew R. Metcalf; Robin Modini; Johannes M�lmenst�dt; Greg Roberts; Taylor Shingler; Siwon Song; Zhen Wang; Anna Wonasch�tz
DOE Research and Development Accomplishments Tag Cloud
Office of Scientific and Technical Information (OSTI)
Database Tag Cloud Database Tag Cloud This tag cloud is a specific type of weighted list that provides a quick look at the content of the DOE R&D Accomplishments database. It can be easily browsed because terms are in alphabetical order. With this tag cloud, there is a direct correlation between font size and quantity. The more times a term appears in the bibliographic citations, the larger the font size. This tag cloud is also interactive. Clicking on a term will activate a search for that term. Search results will then be received. absorption Accelerator Accelerators Acid Acids AEC air Alpha Analysis Angular Applications Applied Argonne Aspects atmospheric Atom Atomic atoms Background Basic Batteries Beam Beams Beta Biological Biology BNL Brookhaven Calculations Calvin Capture carbon Cells CH Change changes Chemical Chemistry CHLORINE climate Coal Collisions complex Complexes Compounds computed Computerized conditions Conservation Conversion Cosmic Cosmology Cross Crystal current cycle data Decay density design Detection detectors development Devices Diagnostic Diffraction Dioxide Discovery distribution DNA Effect Effects Efficiency Electric electricity Electromagnetic Electron Electrons Element elementary elements Emission Energy Environmental Equations even Exchange Experiment Experimental experiments Fermi field fields First Fission Fossil Free fuel fuels Fusion Future Gamma Gas Genome global greenhouse group Hadron Health heat Heating heavy high Historical history Human Hydrocarbons Hydrogen Imaging impacts important Information Institute Interaction Interactions International Invariance ion Ions Isotope Isotopes Kinetics large laser Lawrence LBL LBNL lepton level light Linear Lithium Livermore living LLNL long low Magnetic Mass material Materials mathematics Matter Measurement measurements Mechanics mechanism medical Medicine Mesons Metabolism Method methods Model Models Molecular Molecules momentum mu Nambu Neutral Neutrino Neutrinos Neutron neutrons Nuclear Nuclei Nucleon Odd Organic ORNL Oxides oxygen Particle Particles path PET Photosynthesis physical Physics pi Plants Plasma Plutonium Policy Polymers Positron Power problem processes production program Programs progress Properties Proton Protons Quantum Quark Radiation Radioactive Radioisotopes range Ratio ray Reaction Reactions Reactor Reactors Renewable report Research resolution Resonance results Review RTG scattering science Sciences scientific Seaborg Separation Solar Source Sources Space Spectra Spectroscopy spectrum Spin Stability state States storage Strong Structure Studies study supernovae symmetry Symposium Synthesis system Systems Tau technical Techniques technologies Technology Teller Temperature theoretical Theories Theory Therapy Thermal Thermoelectric Thin Time Tomography Top Tracer Transfer Transport type types Upton Uranium uses Velocity Water Weak Wigner yields
A study of pricing for cloud resources
We present a study of pricing cloud resources in this position paper. Our objective is to explore and understand the interplay between economics and systems designs proposed by recent research. We develop a general model that captures the resource needs ... Keywords: capacity right-sizing, cloud computing, economics, performance guarantees, pricing, throttling
Hong Xu; Baochun Li
Magellan: experiences from a science cloud
Cloud resources promise to be an avenue to address new categories of scientific applications including data-intensive science applications, on-demand/surge computing, and applications that require customized software environments. However, there is a ... Keywords: cloud computing, mapreduce, programming model, science, virtual machines
Lavanya Ramakrishnan; Piotr T. Zbiegel; Scott Campbell; Rick Bradshaw; Richard Shane Canon; Susan Coghlan; Iwona Sakrejda; Narayan Desai; Tina Declerck; Anping Liu
Private virtual infrastructure for cloud computing
Cloud computing places an organization's sensitive data in the control of a third party, introducing a significant level of risk on the privacy and security of the data. We propose a new management and security model for cloud computing called the Private ...
F. John Krautheim
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. ...
A HEART CELL GROUP MODEL FOR THE IDENTIFICATION OF MYOCARDIAL ISCHEMIA Mohamed A. Mneimneh, Micheal signal are an indicator for ischemia. For this purpose, this work proposes an approach based on a heart of 75.66%. 1 INTRODUCTION Ischemic heart disease is the leading cause of death in the world with almost
Povinelli, Richard J.
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
Reflector modelling of small high leakage cores making use of multi-group nodal equivalence theory
This research focuses on modelling reflectors in typical material testing reactors (MTRs). Equivalence theory is used to homogenise and collapse detailed transport solutions to generate equivalent nodal parameters and albedo boundary conditions for reflectors, for subsequent use in full core nodal diffusion codes. This approach to reflector modelling has been shown to be accurate for two-group large commercial light water reactor (LWR) analysis, but has not been investigated for MTRs. MTRs are smaller, with much larger leakage, environment sensitivity and multi-group spectrum dependencies than LWRs. This study aims to determine if this approach to reflector modelling is an accurate and plausible homogenisation technique for the modelling of small MTR cores. The successful implementation will result in simplified core models, better accuracy and improved efficiency of computer simulations. Codes used in this study include SCALE 6.1, OSCAR-4 and EQUIVA (the last two codes are developed and used at Necsa). The results show a five times reduction in calculational time for the proposed reduced reactor model compared to the traditional explicit model. The calculated equivalent parameters however show some sensitivity to the environment used to generate them. Differences in the results compared to the current explicit model, require more careful investigation including comparisons with a reference result, before its implementation can be recommended. (authors)
Theron, S. A. [South African Nuclear Energy Corporation (Necsa), PO Box 582, Pretoria, 0001 (South Africa); Reitsma, F. [Calvera Consultants, PO Box 150, Strubensvallei, 1735 (South Africa)
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
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
Gettelman, Andrew
Building and Connecting to Cloud Services by Using Windows Azure
Building and Connecting to Cloud Services by Using Windows Azure ...for Java developers Information Amazon Elastic Compute Cloud (Amazon EC2). Windows® AzureTM is the Microsoft cloud platform that provides, and provide a standardized runtime environment for your applications. The Windows Azure hosted service model
Hunt, Galen
Rain initiation time in turbulent warm clouds
We present a mean-field model that describes droplet growth due to condensation and collisions and droplet loss due to fallout. The model allows for an effective numerical simulation. We study how the rain initiation time depends on different parameters. We also present a simple model that allows one to estimate the rain initiation time for turbulent clouds with an inhomogeneous concentration of cloud condensation nuclei. In particular, we show that over-seeding even a part of a cloud by small hygroscopic nuclei one can substantially delay the onset of precipitation.
Falkovich, G; Vucelja, M
G. Falkovich; M. G. Stepanov; M. Vucelja
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
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
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
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...
Cloud classification using whole-sky imager data
Clouds are one of the most important moderators of the earth radiation budget and one of the least understood. The effect that clouds have on the reflection and absorption of solar and terrestrial radiation is strongly influenced by their shape, size, and composition. Physically accurate parameterization of clouds is necessary for any general circulation model (GCM) to yield meaningful results. The work presented here is part of a larger project that is aimed at producing realistic three-dimensional (3D) volume renderings of cloud scenes, thereby providing the important shape information for parameterizing GCMs. The specific goal of the current study is to develop an algorithm that automatically classifies (by cloud type) the clouds observed in the scene. This information will assist the volume rendering program in determining the shape of the cloud. Much work has been done on cloud classification using multispectral satellite images. Most of these references use some kind of texture measure to distinguish the different cloud types and some also use topological features (such as cloud/sky connectivity or total number of clouds). A wide variety of classification methods has been used, including neural networks, various types of clustering, and thresholding. The work presented here utilizes binary decision trees to distinguish the different cloud types based on cloud feature vectors.
Buch, K.A. Jr.; Sun, Chen-Hui
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
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
Cloud Computing at NERSC
Cloud Computing Energy Efficient Computing Exascale Computing Performance & Monitoring Tools Petascale Initiative Science Gateway Development Storage and IO Technologies Testbeds...