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Effects of aerosols on deep convective cumulus clouds
E-Print Network (OSTI)
This work investigates the effects of anthropogenic aerosols on deep convective clouds and the associated radiative forcing in the Houston area. The Goddard Cumulus Ensemble model (GCE) coupled with a spectral-bin microphysics is employed to investigate the aerosol effects on clouds and precipitation. First, aerosol indirect effects on clouds are separately investigated under different aerosol compositions, concentrations and size distributions. Then, an updated GCE model coupled with the radiative transfer and land surface processes is employed to investigate the aerosol radiative effects on deep convective clouds. The cloud microphysical and macrophysical properties change considerably with the aerosol properties. With varying the aerosol composition from only (NH4)2SO4, (NH4)2SO4 with soluble organics, to (NH4)2SO4 with slightly soluble organics, the number of activated aerosols decreases gradually, leading to a decrease in the cloud droplet number concentration (CDNC) and an increase in the droplet size. Ice processes are more sensitive to the changes of aerosol chemical properties than the warm rain processes. The most noticeable effect of increasing aerosol number concentrations is an increase of CDNC and cloud water content but a decrease in droplet size. It is indicated that the aerosol indirect effect on deep convection is more pronounced in relatively clean air than in heavily polluted air. The aerosol effects on clouds are strongly dependent on RH: the effect is very significant in humid air. Aerosol radiative effects (ARE) on clouds are very pronounced for mid-visible single-scattering albedo (SSA) of 0.85. Relative to the case without the ARE, cloud fraction and optical depth decrease by about 18% and 20%, respectively. The daytime-mean direct forcing is about 2.2 W m-2 at the TOA and -17.4 W m-2 at the surface. The semi-direct forcing is positive, about 10 and 11.2 W m-2 at the TOA and surface, respectively. Aerosol direct and semi-direct effects are very sensitive to SSA. The cloud fraction, optical depth, convective strength, and precipitation decrease with the increase of absorption, resulting from a more stable atmosphere due to enhanced surface cooling and atmospheric heating.
Fan, Jiwen
Sensitivity of Boundary-layer and Deep Convective Cloud Simulations...
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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...
Possibility of the Visible-Channel Calibration Using Deep Convective Clouds Overshooting the TTL
Science Conference Proceedings (OSTI)
The authors examined the possible use of deep convective clouds (DCCs), defined as clouds that overshoot the tropical tropopause layer (TTL), for the calibration of satellite measurements at solar channels. DCCs are identified in terms of the ...
B-J. Sohn; Seung-Hee Ham; Ping Yang
Microphysical Processes Evident in Aerosol Forcing of Tropical Deep Convective Clouds
This study investigates the effects of aerosols on tropical deep convective clouds (DCCs). A series of large-scale, two-dimensional cloud-resolving model simulations was completed, differing only in the concentration of aerosols available to act ...
Rachel L. Storer; Susan C. van den Heever
Retrieval of Thermodynamic Variables within Deep Convective Clouds: Experiments in Three Dimensions
A three-dimensional thermodynamic retrieval method has been developed and tested for application to deep convective clouds. To test the accuracy of the method and for sensitivity studies, output from a three-dimensional numerical cloud model has ...
Carl E. Hane; Robert B. Wilhelmson; Tzvi Gal-Chen
Cloud and Radiative Characteristics of Tropical Deep Convective Systems in Extended Cloud Objects from CERES Observations
The physical and radiative properties of tropical deep convective systems for the period from January to August 1998 are examined with the use of Clouds and the Earth's Radiant Energy System Single-Scanner Footprint (SSF) data from the Tropical ...
Zachary A. Eitzen; Kuan-Man Xu; Takmeng Wong
Impact of Cloud Cover on Solar Radiative Biases in Deep Convective Regimes
Conflicting claims have been made concerning the magnitude of the bias in solar radiative transfer calculations when horizontal photon transport is neglected for deep convective scenarios. The difficulty of obtaining a realistic set of cloud ...
F. Di Giuseppe; A. M. Tompkins
Effect of Aerosol on Circulations and Precipitation in Deep Convective Clouds
This study examines the effect of a mesoscale perturbation of aerosol on a larger-scale cloud system driven by deep convective clouds. An aerosol-perturbed domain of size 120 km is prescribed in the middle of the larger-scale domain of size 1100 ...
Seoung Soo Lee
Interannual to Diurnal Variations in Tropical and Subtropical Deep Convective Clouds and Convective Overshooting from Seven Years of AMSU-B Measurements
This study surveys interannual to diurnal variations of tropical deep convective clouds and convective overshooting using the Advanced Microwave Sounding Unit B (AMSU-B) aboard the NOAA polar orbiting satellites from 1999 to 2005. The methodology ...
Gang Hong; Georg Heygster; Justus Notholt; Stefan A. Buehler
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
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
Comparison of the Highly Reflective Cloud and Outgoing Longwave Radiation Datasets for Use in Estimating Tropical Deep Convection
Currently, there are two long-term satellite-derived datasets most are frequently used as indices for tropical deep convection. These are the Outgoing Longwave Radiation (OLR) and Highly Reflective Cloud (HRC) datasets. Although both of these ...
Duane E. Waliser; Nicholas E. Graham; Catherine Gautier
Response of Humidity and Clouds to Tropical Deep Convection
Currently available satellite data can be used to track the response of clouds and humidity to intense precipitation events. A compositing technique centered in space and time on locations experiencing high rain rates is used to detail the ...
Mark D. Zelinka; Dennis L. Hartmann
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
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 ...
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
Cloud-Resolving Simulations of Deep Convection over a Heated Mountain
Cloud-resolving numerical simulations of airflow over a diurnally heated mountain ridge are conducted to explore the mechanisms and sensitivities of convective initiation under high pressure conditions. The simulations are based on a well-...
Daniel J. Kirshbaum
A Numerical Investigation of the Structure of vorticity Fields Associated with a Deep Convective Cloud
The structure of vorticity fields of cumulus clouds is studied using a three-dimensional numerical convection model developed by Clark (1977, 1979. 1981). The analysis of the model results suggests that 1) it is justified to neglect the ...
Han-Ru Cho; Terry L. Clark
Preconditioning Deep Convection with Cumulus Congestus
Recent studies have pushed forward the idea that congestus clouds, through their moistening of the atmosphere, could promote deep convection. On the other hand, older studies have tended to relate convective initiation to the large-scale forcing. ...
Cathy Hohenegger; Bjorn Stevens
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
Intercomparison of Deep Convection over the Tibetan Plateau–Asian Monsoon Region and Subtropical North America in Boreal Summer Using CloudSat/CALIPSO Data
Deep convection in the Tibetan Plateau–southern Asian monsoon region (TP–SAMR) is analyzed using CloudSat and Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) data for the boreal summer season (June–August) from 2006 to ...
Yali Luo; Renhe Zhang; Weimiao Qian; Zhengzhao Luo; Xin Hu
Using Digital Cloud Photogrammetry to Characterize the Onset and Transition from Shallow to Deep Convection over Orography
An automated method for segmenting digital images of orographic cumulus and a simple metric for characterizing the transition from shallow to deep convection are presented. The analysis is motivated by the hypothesis that shallow convection ...
Joseph A. Zehnder; Liyan Zhang; Dianne Hansford; Anshuman Radzan; Nancy Selover; Constance M. Brown
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
Interactions between Shallow and Deep Convection under a Finite Departure from Convective Quasi Equilibrium
The present paper presents a simple theory for the transformation of nonprecipitating, shallow convection into precipitating, deep convective clouds. To make the pertinent point a much idealized system is considered, consisting only of shallow and ...
Jun-Ichi Yano; Robert Plant
The Dependence of Storm Longevity on the Pattern of Deep Convection Initiation in a Low-Shear Environment
The sensitivity of storm longevity to the pattern of deep convection initiation (e.g., multiple, quasi-linearly arranged initial deep convective cells versus an isolated deep convective cell) is examined using idealized cloud-resolving simulations ...
Adam L. Houston; Robert B. Wilhelmson
A Mass Flux Convection Scheme with Representation of Cloud Ensemble Characteristics and Stability-Dependent Closure
The convection scheme used at the UK Meteorological Office in large-scale numerical models is described. The scheme uses a "bulk" cloud model to represent an ensemble of convective clouds and aims to represent shallow, deep and midlevel ...
D. Gregory; P. R. Rowntree
Limiting Factors for Convective Cloud Top Height in the Tropics
Limiting Factors for Convective Cloud Top Limiting Factors for Convective Cloud Top Height in the Tropics M. P. Jensen and A. D. Del Genio National Aeronautics and Space Administration Goddard Institute for Space Studies Columbia University New York, New York Introduction Populations of tropical convective clouds are mainly comprised of three types: shallow trade cumulus, mid-level cumulus congestus and deep convective clouds (Johnson et al. 1999). Each of these cloud types has different impacts on the local radiation and water budgets. For climate model applications it is therefore important to understand the factors which determine the type of convective cloud that will occur. In this study, we concentrate on describing the factors that limit the cloud-top heights of mid-
Numerical Modeling of Gravity Wave Generation by Deep Tropical Convection
Although convective clouds are known to generate internal gravity waves, the mechanisms responsible are not well understood. The present study seeks to clarify the dynamics of wave generation using a high-resolution numerical model of deep ...
Todd P. Lane; Michael J. Reeder; Terry L. Clark
A Stochastic Parameterization for Deep Convection Based on Equilibrium Statistics
A stochastic parameterization scheme for deep convection is described, suitable for use in both climate and NWP models. Theoretical arguments and the results of cloud-resolving models are discussed in order to motivate the form of the scheme. In ...
R. S. Plant; G. C. Craig
Wavelet-Compressed Representation of Deep Moist Convection
The capacity of wavelets to effectively represent atmospheric processes under compression is tested by a dataset generated by a cloud-resolving model simulation of deep convective events observed during the Tropical Ocean Global Atmosphere ...
Jun-Ichi Yano; Peter Bechtold; Jean-Luc Redelsperger; Francoise Guichard
Response of Tropical Deep Convection to Localized Heating Perturbations: Implications for Aerosol-Induced Convective Invigoration
A cloud-system-resolving model is used to investigate the effects of localized heating/cooling perturbations on tropical deep convection, in the context of the aerosol "invigoration effect." This effect supposes that a reduction of droplet ...
Hugh Morrison; Wojciech W. Grabowski
Restratification after Deep Convection
An important, yet poorly understood, aspect of the water mass transformation process in the ocean is the manner in which the convected fluid, once formed, is accommodated and drawn into the general circulation. Following "violent mixing" in the ...
Helen Jones; John Marshall
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
Deep Convective Rotational Solitary Waves and Mesoscale Convective Complexes
As an extension of CCI (conditional convective instability) theory, three-dimensional, deep and steady convective waves in a barotropic basic flow with an embedded moist zone were studied via perturbation methods. The basic state is assumed to be ...
Qin Xu
ARM - Midlatitude Continental Convective Clouds
Convective processes play a critical role in the Earth's energy balance through the redistribution of heat and moisture in the atmosphere and their link to the hydrological cycle. Accurate representation of convective processes in numerical models is vital towards improving current and future simulations of Earths climate system. Despite improvements in computing power, current operational weather and global climate models are unable to resolve the natural temporal and spatial scales important to convective processes and therefore must turn to parameterization schemes to represent these processes. In turn, parameterization schemes in cloud-resolving models need to be evaluated for their generality and application to a variety of atmospheric conditions. Data from field campaigns with appropriate forcing descriptors have been traditionally used by modelers for evaluating and improving parameterization schemes.
Mike Jensen; Mary Jane Bartholomew; Anthony Del Genio; Scott Giangrande; Pavlos Kollias
DOE Data Explorer (OSTI)
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 Sensitivity of Convective Initiation to the Lapse Rate of the Active Cloud-Bearing Layer
Numerical experiments are conducted using an idealized cloud-resolving model to explore the sensitivity of deep convective initiation (DCI) to the lapse rate of the active cloud-bearing layer [ACBL; the atmospheric layer above the level of free ...
Adam L. Houston; Dev Niyogi
Improving satellite-based convective cloud growth monitoring with visible optical depth retrievals
The use of geostationary satellites for monitoring the development of deep convective clouds has been recently well documented. One such approach, the University of Wisconsin Cloud-Top Cooling Rate (CTC) algorithm utilizes frequent GOES ...
Justin M. Sieglaff; Lee M. Cronce; Wayne F. Feltz
Technical Sessions Parameterization of Convective Clouds, Mesoscale...
and Convective-Generated Clouds W. R. Cotton Department of Atmospheric Science Colorado State University Fort Collins, CO 80523 This presentation is a summary of research...
What Controls the Transition from Shallow to Deep Convection?
In this study, a 2D cloud-system-resolving model (CSRM) is used to assess the control mechanism for the transition from shallow to deep convection in the diurnal cycle over land. By comparing with a 3D CSRM under conditions taken from the Large-...
Chien-Ming Wu; Bjorn Stevens; Akio Arakawa
A Satellite-Based Convective Cloud Object Tracking and Multipurpose Data Fusion Tool with Application to Developing Convection
Studying deep convective clouds requires the use of available observation platforms with high temporal and spatial resolution, as well as other non–remote sensing meteorological data (i.e., numerical weather prediction model output, conventional ...
Justin M. Sieglaff; Daniel C. Hartung; Wayne F. Feltz; Lee M. Cronce; Valliappa Lakshmanan
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
A Numerical Investigation of the Effects of Dry Air Aloft on Deep Convection
A three-dimensional cloud model was used to investigate the sensitivity of deep convective storms to dry air above the cloud base. In simulations of both quasi-linear convective systems and supercells, dry air aloft was found to reduce the ...
Richard P. James; Paul M. Markowski
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
A Numerical Simulation of Convectively Induced Turbulence above Deep Convection
At 1034 UTC 2 September 2007, a commercial aircraft flying from Jeju, South Korea, to Osaka, Japan, at an altitude of approximately 11.2 km encountered severe turbulence above deep convection. To investigate the characteristics and generation ...
Jung-Hoon Kim; Hye-Yeong Chun
Some Influences of Background Flow Conditions on the Generation of Turbulence due to Gravity Wave Breaking above Deep Convection
Deep moist convection generates turbulence in the clear air above and around developing clouds, penetrating convective updrafts and mature thunderstorms. This turbulence can be due to shearing instabilities caused by strong flow deformations near ...
Todd P. Lane; Robert D. Sharman
A Satellite Analysis of Deep Convection, Upper-Tropospheric Humidity, and the Greenhouse Effect
This paper combines satellite measurements of the upwelling 6.7-?m radiance from TOVS with cloud-property information from ISCCP and outgoing longwave radiative fluxes from ERBE to analyze the climatological interactions between deep convection, ...
Brian J. Soden; Rong Fu
The Interaction Between Deep Convection and Easterly Waves over Tropical North Africa: A Weather State Perspective
The interaction between deep convection and easterly waves over tropical North Africa is studied using a weather state (WS) dataset from the International Cloud Climatology Project (ISCCP) and reanalysis products from the European Centre for ...
Ademe Mekonnen; William B. Rossow
Integral Effects of Deep Convection
The large-scale, integral effect of convective elements (plumes) constituting an open-ocean chimney is investigated both theoretically and with a plume-resolving numerical model. The authors consider an initially homogeneous "patch" of ocean of ...
Uwe Send; John Marshall
A Simple Method for Measuring Deep Convection
The glass-pipe technology used for RAFOS floats is applied to the monitoring of convection in deep mixed layers. The velocity of a vertical current is estimated from the relationship between the drag force exerted on a float by the vertical ...
Edward J. Kearns; H. Thomas Rossby
A Numerical Investigation of Several Factors Contributing to the Observed Variable Intensity of Deep Convection over South Florida
This study employs a revised version of the Colorado State University three-dimensional numerical cloud scale model to investigate the observed behavior of deep convection over South Florida on 17 July 1973. A brief description of recent model ...
Gregory J. Tripoli; William R. Cotton
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
Factors Governing the Total Rainfall Yield from Continental Convective Clouds
Several important factors that govern the total rainfall from continental convective clouds were investigated by tracking thousands of convective cells in Israel and South Africa. The rainfall volume yield (Rvol) of the individual cells that ...
Daniel Rosenfeld; Abraham Gagin
Cloud-to-Ground Lightning Activity in Mesoscale Convective Complexes
A study of cloud-to-ground lightning activity attending an important subclass of mesoscale convective weather systems called the mesoscale convective complex shows that groun discharge flash rates in excess of 1000 h?1 can be sustained on average ...
S. J. Goodman; D. R. MacGorman
ARM - Field Campaign - Midlatitude Continental Convective Clouds Experiment
Experiment (MC3E) Experiment (MC3E) Campaign Links Science Plan MC3E Website Related Campaigns Midlatitude Continental Convective Clouds Experiment: 2DVD Support 2011.04.22, Schwaller, SGP Midlatitude Continental Convective Clouds Experiment (MC3E): Airborne Instruments 2011.04.22, Poellot, AAF Midlatitude Continental Convective Clouds Experiment (MC3E): Multi-Frequency Profilers 2011.04.22, Williams, SGP Midlatitude Continental Convective Clouds Experiment: Parsivel Disdrometer Support 2011.04.22, Schwaller, SGP Midlatitude Continental Convective Clouds Experiment (MC3E): Inner Domain Thermodynamic Profiling during MC3E 2011.04.22, Turner, SGP Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Campaign : Midlatitude Continental Convective Clouds Experiment (MC3E)
Processes of Hydrometeor Development in Oklahoma Convective Clouds
This study employs in situ measurements to examine cloud conditions in which hydrometeors develop in mature Oklahoma convective clouds and to develop hypotheses as to how they formed. The measurements were made from penetrations on six days using ...
Andrew J. Heymsfield; Mark R. Hjelmfelt
Cycles and Propagation of Deep Convection over Equatorial Africa
Long-term statistics of organized convection are vital to improved understanding of the hydrologic cycle at various scales. Satellite observations are used to understand the timing, duration, and frequency of deep convection in equatorial Africa, ...
Arlene G. Laing; Richard E. Carbone; Vincenzo Levizzani
Resonant Response of Deep Convection to Surface Hot Spots
Observations show substantial variations of the intensity of tropical and/or summertime deep convection on land that are not explained by standard measures of convective instability. One feature that distinguishes land surfaces is their ...
F. J. Robinson; S. C. Sherwood; Y. Li
A Parameter Study of Interactions Between Convective Clouds, the Convective Boundary Layer, and a Forested Surface
A numerical model was developed which included cloud parameterizations, a convective boundary layer, solar and longwave radiation, a soil layer and a parameterized forest layer. The model simulated the growth of the convective boundary layer and ...
Alfred J. Garrett
New Insights Into Deep Convective Core Vertical Velocities Using...
Insights Into Deep Convective Core Vertical Velocities Using ARM UHF Wind Profilers For original submission and image(s), see ARM Research Highlights http:www.arm.govscience...
Sensitivity of Convective Cloud Growth to Mesoscale Lifting: A Numerical Analysis of Mesoscale Convective Triggering
Numerical model simulation of mesoscale lifting of the convective environment indicates that the ability of the environment to develop deep moist convection increases as mesoscale lifting increases. Mesoscale lifting produces increases in modeled ...
David A. Matthews; Bernard A. Silverman
GEWEX Cloud System Study (GCSS) Working Group 4: Precipitating Convective Cloud Systems
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
Potential Aerosol Indirect Effects on Atmospheric Circulation and Radiative Forcing through Deep Convection
Aerosol indirect effects, i.e., the interactions of aerosols with clouds by serving as cloud condensation nuclei (CCN) or ice nuclei (IN), constitute the largest uncertainty in climate forcing and projection. Previous IPCC reported aerosol indirect forcing is negative, which does not account for aerosol-convective cloud interactions because the complex processes involved are poorly understood and represented in climate models. Here we report that aerosol indirect effect on deep convective cloud systems can lead to enhanced regional convergence and a strong top-of atmosphere (TOA) warming. Aerosol invigoration effect on convection can result in a strong radiative warming in the atmosphere (+5.6 W m-2) due to strong night-time warming, a lofted latent heating, and a reduced diurnal temperature difference, all of which could remarkably impact regional circulation and modify weather systems. We further elucidated how aerosols change convective intensity, diabatic heating, and regional circulation under different environmental conditions and concluded that wind shear and cloud base temperature play key roles in determining the significance of aerosol invigoration effect for convective systems.
Fan, Jiwen; Rosenfeld, Daniel; Ding, Yanni; Leung, Lai-Yung R.; Li, Zhanqing
BNL | Midlatitude Continental Convective Clouds Experiment (MC3E)
Midlatitude Continental Convective Clouds Experiment Midlatitude Continental Convective Clouds Experiment Convective processes play a critical role in the Earth's energy balance through the redistribution of heat and moisture in the atmosphere and their link to the hydrological cycle. Accurate representation of convective processes in numerical models is vital towards improving current and future simulations of Earths climate system. Despite improvements in computing power, current operational weather and global climate models are unable to resolve the natural temporal and spatial scales important to convective processes and therefore must turn to parameterization schemes to represent these processes. In turn, parameterization schemes in cloud-resolving models need to be evaluated for their generality and application to a
Positive Cloud-to-Ground Lightning in Mesoscale Convective Systems
We have examined the characteristics of positive cloud-to-ground lightning flashes in Mesoscale Convective Systems observed during the Oklahoma-Kansas PRE-STORM project in 1985. Lightning frequencies and patterns of ground strike locations are ...
Steven A. Rutledge; Chungu Lu; Donald R. MacGorman
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
Resolution Requirements for the Simulation of Deep Moist Convection
The spatial resolution appropriate for the simulation of deep moist convection is addressed from a turbulence perspective. To provide a clear theoretical framework for the problem, techniques for simulating turbulent flows are reviewed, and the ...
George H. Bryan; John C. Wyngaard; J. Michael Fritsch
Deep Convective System Evolution over Africa and the Tropical Atlantic
In the tropical African and neighboring Atlantic region there is a strong contrast in the properties of deep convection between land and ocean. Here, satellite radar observations are used to produce a composite picture of the life cycle of ...
Joanna M. Futyan; Anthony D. Del Genio
An Investigation of Turbulence Generation Mechanisms above Deep Convection
An investigation of the generation of turbulence above deep convection is presented. This investigation is motivated by an encounter between a commercial passenger aircraft and severe turbulence above a developing thunderstorm near Dickinson, ...
Todd P. Lane; Robert D. Sharman; Terry L. Clark; Hsiao-Ming Hsu
Another Look at the Thermodynamic Equation For Deep Convection
The study considers deep moist convection involving only a liquid-vapor phase change. An alternative form of the classical thermodynamic equation for reversible saturated flow is derived. Four approximate forms of this equation are obtained and ...
Frank B. Lipps; Richard S. Hemler
Upscale Effects of Deep Convection during the North American Monsoon
The ability of deep monsoon convection to influence the larger-scale circulation over North America is investigated for a 6-day long case study during the 2006 North American monsoon season. Results from Rossby wave ray tracing and numerical ...
David J. Stensrud
Numerical Simulation of Ice-Phase Convective Cloud Seeding
A two-dimensional time-dependent cloud model which covers a region 19.2 km × 19.2 km in the x and z directions with 200 m grid intervals, has been used to simulate silver iodide (AgI) seeding effects on strong convective clouds. The model is a ...
Eirh-Yu Hsie; Richard D. Farley; Harold D. Orville
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
Unsteady, Turbulent Convection into a Rotating, Linearly Stratified Fluid: Modeling Deep Ocean Convection
A laboratory experiment has been constructed to Model the deep convective processes in a stratified ocean driven by the energetic cooling at the ocean surface. For convenience in the laboratory the authors have examined the analogous but inverted ...
M. J. Coates; G. N. Ivey; J. R. Taylor
Deep Convection on Day 261 of GATE
Aircraft, radar, satellite and ship data, gathered on 18 September 1974 during GATE, have been brought to bear an clouds of the middle and upper troposphere associated with a cloud cluster occurring near the ridge axis of a 700 mb wave.
C. Warner; J. Simpson; G. Van Helvoirt; D. W. Martin; D. Suchman; G. L. Austin
Midlatitude Continental Convective Clouds Experiment Science...
aircraft will fly above and within the clouds while radar systems scan through the storm from multiple locations. At the same time, additional ground-based instruments will...
A Funnel Cloud in a Convective Cloud Line to the Rear of a Surface Cold Front
This brief case study describes the unusually benign environment in which a funnel cloud formed along a line of convective towers during the summer in Kansas. The parent cloud line was solitary and very narrow, yet organized on the mesoscale. The ...
Howard B. Bluestein
Small-Scale Moist Turbulence in Numerically Generated Convective Clouds
The authors present simulations of cloud-free and cloudy, nonprecipitating, convective turbulence at spatial resolutions down to ?x = 2.6 m for a domain size of (1 km)3. The runs are analyzed with attention focused on the dynamical differences ...
K. Spyksma; P. Bartello
Cloud-Level Penetrative Compressible Convection in the Venus Atmosphere
A two-dimensional, nonlinear, fully compressible model of a perfect gas is used to simulate cloud-level penetrative convection in the Venus atmosphere from 40 to 60 km altitude. Three cases with different amounts of solar heating are considered: ...
R. David Baker; Gerald Schubert; Philip W. Jones
The convective structures associated with cloud-to-ground lightning in TOGA COARE Mesoscale Convective Systems
The TOGA COARE experiment was carried out in the western Pacific warm pool region from November 1992 through February 1993. Data from TOGA COARE provide the opportunity for comprehensive studies of tropical oceanic convection. This study seeks to understand more about the structures of tropical mesoscale convective systems in relation to their lightning activity and cold cloud area. The properties of convective cores within the MCSs, as well as their infrared (IR) cloud top temperatures are related to cloud-to-ground lightning. IR and lightning time histories for each case are compared, and the cases ranked by mean flashes per 10000 km2. For selected cases, radar/lightning overlays and vertical profiles of maximum radar reflectivities (VPRRs) are shown in order to describe the convective structures of cells that produced lightning, and also cells that did not produce lightning. IR cloud-top temperature and lightning histories indicate the highly variable nature of the TOGA COARE MCSs. Some MCSs which have very cold cloud-top temperatures have little or no lightning. When a system did produce lightning, more flashes generally occurred during its growth phase. Overall, IR measurements seem to be a poor indicator of lightning due to the lack of a clear relationship between the size of cold cloud-top area and cloud-to-ground flashes. The overall flash rates of the TOGA COARE MCSs support previous work which showed that tropical oceanic convection has an order of magnitude less cloud-to-ground lightning than continental convection. In fact, the highest flash rate for the 13 cases was less than the weakest continental case in a Texas MCS study (Toracinta et al. 1995). Examination of individual VPRR and of all convective VPRR from the 13 cases indicate a pronounced difference between lightning producing and non-lightning producing cells. Lightning producing convective cells have higher radar reflectivity in the 5.0- 8.0 km layer, and a slower decrease with height, both observations indicating larger ice particles in the mixed phase region between 00 C and-200 C.
Restivo, Michael Edward
A Systemic Analysis of Multiscale Deep Convective Variability over the Tropical Pacific
The multiscale tropical deep convective variability over the Pacific Ocean is examined with the 4-month high-resolution deep convection index (ITBB) derived from satellite imagery. With a systemic view, the complex phenomenon is described with ...
Wen-wen Tung; Mitchell W. Moncrieff; Jian-Bo Gao
The ability of deep monsoon convection to influence the larger-scale circulation over North America is investigated for a 6-day-long case study during the 2006 North American monsoon. Results from Rossby wave ray tracing and numerical simulations ...
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
Midlatitude Continental Convective Clouds Experiment (MC3E)
SciTech Connect
Convective processes play a critical role in the Earth's energy balance through the redistribution of heat and moisture in the atmosphere and subsequent impacts on the hydrologic cycle. Global observation and accurate representation of these processes in numerical models is vital to improving our current understanding and future simulations of Earth's climate system. Despite improvements in computing power, current operational weather and global climate models are unable to resolve the natural temporal and spatial scales that are associated with convective and stratiform precipitation processes; therefore, they must turn to parameterization schemes to represent these processes. In turn, the physical basis for these parameterization schemes needs to be evaluated for general application under a variety of atmospheric conditions. Analogously, space-based remote sensing algorithms designed to retrieve related cloud and precipitation information for use in hydrological, climate, and numerical weather prediction applications often rely on physical "parameterizations" that reliably translate indirectly related instrument measurements to the physical quantity of interest (e.g., precipitation rate). Importantly, both spaceborne retrieval algorithms and model convective parameterization schemes traditionally rely on field campaign data sets as a basis for evaluating and improving the physics of their respective approaches. The Midlatitude Continental Convective Clouds Experiment (MC3E) will take place in central Oklahoma during the April–May 2011 period. The experiment is a collaborative effort between the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility and the National Aeronautics and Space Administration's (NASA) Global Precipitation Measurement (GPM) mission Ground Validation (GV) program. The field campaign leverages the unprecedented observing infrastructure currently available in the central United States, combined with an extensive sounding array, remote sensing and in situ aircraft observations, NASA GPM ground validation remote sensors, and new ARM instrumentation purchased with American Recovery and Reinvestment Act funding. The overarching goal is to provide the most complete characterization of convective cloud systems, precipitation, and the environment that has ever been obtained, providing constraints for model cumulus parameterizations and space-based rainfall retrieval algorithms over land that have never before been available. Several different components of convective cloud and precipitation processes tangible to both the convective parameterization and precipitation retrieval algorithm problem are targeted, such as preconvective environment and convective initiation, updraft/downdraft dynamics, condensate transport and detrainment, precipitation and cloud microphysics, spatial and temporal variability of precipitation, influence on the environment and radiation, and a detailed description of the large-scale forcing.
Jensen, MP; Petersen, WA; Del Genio, AD; Giangrande, SE; Heymsfield, A; Heymsfield, G; Hou, AY; Kollias, P; Orr, B; Rutledge, SA; Schwaller, MR; Zipser, E
Experiment Experiment (MC3E): Multi-Frequency Profilers Related Campaigns Midlatitude Continental Convective Clouds Experiment (MC3E) 2011.04.22, Jensen, SGP Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Campaign : Midlatitude Continental Convective Clouds Experiment (MC3E): Multi-Frequency Profilers 2011.04.22 - 2011.06.06 Lead Scientist : Christopher Williams For data sets, see below. Description The scientific focus was to study the vertical structure of precipitation in a vertical column over the SGP Central Facility. These multi-frequency profiler observations enabled directly measuring the vertical air motion and retrieving the raindrop size distributions from near the surface to just under the freezing level. These profilers were deployed during MC3E
ARM - Midlatitude Continental Convective Clouds (comstock-hvps)
Mike Jensen; Jennifer Comstock; Anthony Del Genio; Scott Giangrande; Pavlos Kollias
An Idealized Cloud-Resolving Framework for the Study of Midlatitude Diurnal Convection over Land
This paper introduces an idealized cloud-resolving modeling (CRM) framework for the study of midlatitude diurnal convection over land. The framework is used to study the feedbacks among soil, boundary layer, and diurnal convection. It includes a ...
Linda Schlemmer; Cathy Hohenegger; Jürg Schmidli; Christopher S. Bretherton; Christoph Schär
Radar Analysis of a Tropical Convective Boundary Layer with Shallow Cumulus Clouds
A situation of fair weather cloudy convection is examined using a dual Doppler radar, environmental measurements and cloud photogrammetry. The convective layer is characterized by the interaction between the northward monsoon wind at low levels ...
Laurence Eymard
On the Modification Potential of Illinois Summertime Convective Clouds, with Comparisons to Florida and FACE Observations
The potential for enhancing rain output over central Illinois through modification of summertime convective clouds was investigated by use of model predictions of cumulus growth, as well as direct, internal measurements of cloud physical ...
Victor Wiggert; Robert I. Sax; Ronald L. Holle
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
Aerosol Effects of the Condensation Process on a Convective Cloud Simulation
Using a nonhydrostatic model with a double-moment bulk cloud microphysics scheme, we introduce an aerosol effect on a convective cloud system by accelerating the condensation and evaporation processes (the aerosol condensational effect). To ...
Tatsuya Seiki; Teruyuki Nakajima
A Satellite-Based Parameter to Monitor the Aerosol Impact on Convective Clouds
A method to monitor the aerosol impact on convective clouds using satellite data is presented. The impacts of forest fires and highly polluting megacities on cloud precipitation formation processes are quantified by the vertical extent above ...
Itamar M. Lensky; Ron Drori
Observational Study of the Entrainment-Mixing Process in Warm Convective Clouds
Thermodynamical and microphysical measurements collected in convective clouds are examined within the frame of the homogeneous/inhomogeneous mixing concept, to determine how entrainment-mixing processes affect cloud droplets, their number ...
Frédéric Burnet; Jean-Louis Brenguier
Deep convection triggering by boundary layer thermals. Part 1: LES analysis and stochastic triggering formulation
This paper proposes a new formulation of the deep convection triggering for GCM (General Circulation Model) convective parameterizations. This triggering is driven by evolving properties of the strongest boundary-layer thermals. To investigate ...
Nicolas Rochetin; Fleur Couvreux; Jean-Yves Grandpeix; Catherine Rio
The Role of Cloud Microphysics Parameterization in the Simulation of Mesoscale Convective System Clouds and Precipitation in the Tropical Western Pacific
This paper presents a detailed analysis of convection-permitting cloud simulations, aimed at increasing the understanding of the role of parameterized cloud microphysics in the simulation of mesoscale convective systems (MCSs) in the tropical ...
K. Van Weverberg; A. M. Vogelmann; W. Lin; E. P. Luke; A. Cialella; P. Minnis; M. Khaiyer; E. R. Boer; M. P. Jensen
Long-Term Simulations of Thermally Driven Flows and Orographic Convection at Convection-Parameterizing and Cloud-Resolving Resolutions
The purpose of this paper is to validate the representation of topographic flows and moist convection over the European Alps in a convection-parameterizing simulation (CPM; ?x = 6.6 km) and two cloud-resolving simulations (CRM; ?x = 1.1 and 2.2 km)...
Wolfgang Langhans; Juerg Schmidli; Oliver Fuhrer; Susanne Bieri; Christoph Schär
A Cloud-Base Quasi-Balance Constraint for Parameterized Convection: Application to the Kain–Fritsch Cumulus Scheme
A quasi balance with respect to parcel buoyancy at cloud base between destabilizing processes and convection is imposed as a constraint on convective cloud-base mass flux in a modified version of the Kain–Fritsch cumulus parameterization. ...
James A. Ridout; Yi Jin; Chi-Sann Liou
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.
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 ...
Deep Convection and "First Echoes" within Anvil Precipitation
The development of convective cells within anvil precipitation, in a region of moderate convective activity that might be called a small mesoscale convective system, is described and discussed. The presence of precipitation-sized hydrometeors in ...
Charles A. Knight; L. Jay Miller; William D. Hall
ARM - Midlatitude Continental Convective Clouds (jensen-sonde)
A major component of the Mid-latitude Continental Convective Clouds Experiment (MC3E) field campaign was the deployment of an enhanced radiosonde array designed to capture the vertical profile of atmospheric state variables (pressure, temperature, humidity wind speed and wind direction) for the purpose of deriving the large-scale forcing for use in modeling studies. The radiosonde array included six sites (enhanced Central Facility [CF-1] plus five new sites) launching radiosondes at 3-6 hour sampling intervals. The network will cover an area of approximately (300)2 km2 with five outer sounding launch sites and one central launch location. The five outer sounding launch sites are: S01 Pratt, KS [ 37.7oN, 98.75oW]; S02 Chanute, KS [37.674, 95.488]; S03 Vici, Oklahoma [36.071, -99.204]; S04 Morris, Oklahoma [35.687, -95.856]; and S05 Purcell, Oklahoma [34.985, -97.522]. Soundings from the SGP Central Facility during MC3E can be retrieved from the regular ARM archive. During routine MC3E operations 4 radiosondes were launched from each of these sites (approx. 0130, 0730, 1330 and 1930 UTC). On days that were forecast to be convective up to four additional launches were launched at each site (approx. 0430, 1030, 1630, 2230 UTC). There were a total of approximately 14 of these high frequency launch days over the course of the experiment.
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.
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
Structural Characteristics of Deep Convective Systems over Tropical Africa and the Atlantic Ocean
The structural properties of convective cloud clusters of tropical Africa and the Atlantic Ocean are studied using six summers of Meteosat satellite data in the atmospheric infrared window. A cluster at a given brightness temperature threshold is ...
L. A. Toledo Machado; M. Desbois; J-Ph Duvel
Evolution of the Vertical Mass Flux and Diagnosed Net Lateral Mixing in Isolated Convective Clouds
The evolution of the vertical mass flux in isolated cumulus and cumulus congestus clouds is documented using two King Airs during the Convection and Precipitation/Electrification Experiment (CaPE,), conducted in east-central Florida during the ...
Gary M. Barnes; James C. Fankhauser; Wesley D. Browning
A Satellite-Based Summer Convective Cloud Frequency Analysis over the Southeastern United States
A convective cloud (CC) analysis is performed over the southeastern United States (SEUS) during June, July, and August 2006 and 2007, using data from the Geostationary Operational Environmental Satellite (GOES) visible and infrared sensors as ...
Laci D. Gambill; John R. Mecikalski
On the Identification of the Large-Scale Properties of Tropical Convection using Cloud Regimes
The use of cloud regimes in identifying tropical convection and the associated large-scale atmospheric properties is investigated. The regimes are derived by applying cluster analysis to satellite retrievals of daytime-averaged frequency ...
Jackson Tan; Christian Jakob; Todd P. Lane
A Sensitivity Study of Convective Cloud Formation by Vegetation Forcing with Different Atmospheric Conditions
Variable vegetation cover is a possible trigger for convection, especially in semiarid areas due to differential surface forcing. A two-dimensional numerical model with explicit cloud physics and a detailed vegetation parameterization scheme is ...
Xiaodong Hong; Martin J. Leach; Sethu Raman
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
Monitoring Mesoscale Convective Cloud Systems Associated with Heavy Storms Using Meteosat Imagery
In this study, an automatic algorithm for monitoring areas of cold cloud tops within mesoscale convective systems that produced floods in Greece is developed. The technique is based on Meteosat infrared and water vapor images. The purpose of the ...
Haralambos Feidas; Constantinos Cartalis
Impact of Local Convective Cloud Systems on Summer Daytime Shelter Temperature
The potential impact of daytime local summer convective cloud systems on shelter air temperature is illustrated by numerical modeling and observations. Prolonged reductions in surface solar irradiance due to cloudiness result in a noticeable ...
Moti Segal; Graham Feingold
Fully Lagrangian Floats in Labrador Sea Deep Convection: Comparison of Numerical and Experimental Results
Measurements of deep convection from fully Lagrangian floats deployed in the Labrador Sea during February and March 1997 are compared with results from model drifters embedded in a large eddy simulation (LES) of the rapidly deepening mixed layer. ...
Ramsey R. Harcourt; Elizabeth L. Steffen; Roland W. Garwood; Eric A. D'Asaro
Influence of Ocean Surface Conditions on Atmospheric Vertical Thermodynamic Structure and Deep Convection
The authors analyze the influence of sea surface temperature (SST) and surface wind divergence on atmospheric thermodynamic structure and the resulting effects on the occurrence of deep convection using National Meteorological Center radiosonde ...
Rong Fu; Anthony D. Del Genio; William B. Rossow
Latent Heating and Mixing Due to Entrainment in Tropical Deep Convection
Recent studies have noted the role of latent heating above the freezing level in reconciling Riehl and Malkus' Hot Tower Hypothesis (HTH) with evidence of diluted tropical deep convective cores. This study evaluates recent modifications to the HTH ...
Clayton J. McGee; Susan C. van den Heever
Influence of Sea Surface Temperature on Humidity and Temperature in the Outflow of Tropical Deep Convection
Multiple years of measurements of tropical upper-tropospheric temperature and humidity by the Measurement of Ozone and Water Vapor by Airbus In-Service Aircraft (MOZAIC) project are analyzed in the vicinity of deep convective outflow to study the ...
Zhengzhao Johnny Luo; Dieter Kley; Richard H. Johnson; G. Y. Liu; Susanne Nawrath; Herman G. J. Smit
Scaling Evaluation of the Effect of Surface Characteristics on Potential for Deep Convection over Uniform Terrain
The effect of surface characteristics on the daytime change in the potential for development of deep convection resulting from surface flux of heat and moisture is evaluated by conceptual, scaling, and numerical modeling approaches. It is shown ...
M. Segal; R. W. Arritt; C. Clark; R. Rabin; J. Brown
The Suppression of Deep Moist Convection near the Southern Great Plains Dryline
Deep moist convection failed to initiate over the Texas Panhandle on 6 May 1995 despite expectations to the contrary by the forecasters for the Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX). The National Centers for ...
Harald Richter; Lance F. Bosart
Deep convection triggering by boundary layer thermals. Part 2: Stochastic triggering parametrization for the LMDZ GCM
This paper presents a stochastic triggering parameterization for deep convection and its implementation in the latest standard version of the LMD's GCM: LMDZ5B. The derivation of the formulation of this parameterization and the justification, ...
Nicolas Rochetin; Jean-Yves Grandpeix; Catherine Rio; Fleur Couvreux
Modulation of Internal Gravity Waves in a Multiscale Model for Deep Convection on Mesoscales
Starting from the conservation laws for mass, momentum, and energy together with a three-species bulk microphysics model, a model for the interaction of internal gravity waves and deep convective hot towers is derived using multiscale asymptotic ...
Daniel Ruprecht; Rupert Klein; Andrew J. Majda
A Simple Multicloud Parameterization for Convectively Coupled Tropical Waves. Part II: Nonlinear Simulations
Observations in the Tropics point to the important role of three cloud types, congestus, stratiform, and deep convective clouds, besides ubiquitous shallow boundary layer clouds for both the climatology and large-scale organized anomalies such as ...
Boualem Khouider; Andrew J. Majda
Physical Response of Convective Clouds over the Sierra Nevada to Seeding with Dry Ice
The effect of seeding convective clouds with dry ice was studied using simultaneous aircraft and radar observations. Clouds that were initially ice-free with supercooled liquid water contents of 0.5 g m?3 when the tops reached the ?10°C level had ...
Arlen W. Huggins; Alfred R. Rodi
Katabatic Flows and Their Relation to the Formation of Convective Clouds—Idealized Case Studies
The formation of a convective cloud system as a result of a katabatic-induced surface cold front at the eastern Andes Mountains of South America was investigated in a numerical model study. The occurrence of this cloud system is hypothesized to be ...
Katja Trachte; Joerg Bendix
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
The Diurnal Cycle of the Boundary Layer, Convection, Clouds, and Surface Radiation in a Coastal Monsoon Environment (Darwin, Australia)
The diurnal variation of convection and associated cloud and radiative properties remains a significant issue in global NWP and climate models. This study analyzes observed diurnal variability of convection in a coastal monsoonal environment ...
Peter T. May; Charles N. Long; Alain Protat
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
Mesoscale Convective Vortices Observed during BAMEX. Part II: Influences on Secondary Deep Convection
Observations from the Bow Echo and Mesoscale Convective Vortex (MCV) Experiment are used to examine the role of the five mesoscale convective vortices described in Part I on heavy precipitation during the daytime heating cycle. Persistent ...
Stanley B. Trier; Christopher A. Davis
Temperature–Moisture Dependence of the Deep Convective Transition as a Constraint on Entrainment in Climate Models
Properties of the transition to strong deep convection, as previously observed in satellite precipitation statistics, are analyzed using parcel stability computations and a convective plume velocity equation. A set of alternative entrainment ...
Sandeep Sahany; J. David Neelin; Katrina Hales; Richard B. Neale
Characteristics of Deep Tropical and Subtropical Convection from Nadir-Viewing High-Altitude Airborne Doppler Radar
This paper presents observations of deep convection characteristics in the tropics and subtropics that have been classified into four categories: tropical cyclone, oceanic, land, and sea breeze. Vertical velocities in the convection were derived ...
Gerald M. Heymsfield; Lin Tian; Andrew J. Heymsfield; Lihua Li; Stephen Guimond
The Manifestation of the Madden–Julian Oscillation in Global Deep Convection and in the Schumann Resonance Intensity
This study determines the relationship between intraseasonal oscillations observed in two independent measures of global lightning activity: a global mean convective index (a proxy for deep convection) derived from the Goddard Television Infrared ...
E. Anyamba; E. Williams; J. Susskind; A. Fraser-Smith; M. Fullekrug
The Relative Importance of Northern Overflow and Subpolar Deep Convection for the North Atlantic Thermohaline Circulation
The relative importance of the formation of different North Atlantic Deep Water masses on the meridional overturning is examined with a non-eddy-resolving version of the CME model. In contrast to a frequently held belief, convective deep-water ...
Ralf Döscher; René Redler
Insights into Cloud-Top Height and Dynamics from the Seasonal Cycle of Cloud-Top Heights Observed by MISR in the West Pacific Region
The connection between environmental stability and the height of tropical deep convective clouds is analyzed using stereo cloud height data from the Multiangle Imaging Spectroradiometer (MISR), focusing on the seasonal cycle of clouds over the ...
Jung Hyo Chae; Steven C. Sherwood
Observed Evolution of Tropical Deep Convective Events and Their Environment
Using a compositing technique, the temporal progression of tropical convective systems and the mean atmospheric state in their vicinity is constructed from a time series of geostationary satellite and operational rawinsonde data. The technique ...
Steven C. Sherwood; Ralph Wahrlich
Reply to "Comments on 'Preconditioning Deep Convection with Cumulus Congestus'"
In his comment, D. M. Schultz asked for clarification concerning (i) the validity of the results of C. Hohenegger and B. Stevens for the development of convection over the midlatitudes and (ii) the exact meaning and computation of the term "...
Effects of Downdrafts and Mesoscale Convective Organization on the Heat and Moisture Budgets of Tropical Cloud Clusters. Part III: Effects of Mesoscale Convective Organization
The effects of mesoscale convective organization on the large-scale heat and moisture budgets of tropical cloud clusters are studied using the GATE Phase III data. Two basic questions concerning the mesoscale effects are addressed: 1) the ...
Ming-Dean Cheng; Michio Yanai
The Roles of Dry Convection, Cloud-Radiation Feedback Processes and the Influence of Recent Improvements in the Parameterization of Convection in the GLA GCM
The sensitivity of the simulated July circulation to modifications in the parameterization of dry and moist convection, evaporation from failing raindrops, and cloud-radiation interaction is examined with the GLA (Goddard Laboratory for ...
Y. Sud; A. Molod
The Response of a Deep Cumulus Convection Model to Changes in Radiative Heating
A bulk diagnostic model is presented for the evaluation of the mass and heat fluxes due to convective ensembles. The cloud model is consistent with the hot-tower hypothesis and includes a moist downdraft, the depth and intensity of which are ...
Graeme L. Stephens; Kenneth J. Wilson
Thermodynamic Environments of Deep Convection in Atlantic Tropical Disturbances
Conditional composites of dropsondes deployed into eight tropical Atlantic weather systems during 2010 are analyzed. The samples are conditioned based on cloud-top temperature within 10 km of the dropsonde, the radius from the cyclonic circulation ...
Christopher A. Davis; David A. Ahijevych
From Hot Towers to TRMM: Joanne Simpson and Advances in Tropical Convection Research
Joanne Simpson began contributing to advances in tropical convection about half a century ago. The hot tower hypothesis jointly put forth by Joanne Simpson and Herbert Riehl postulated that deep convective clouds populating the "equatorial trough ...
Radiative and Convective Driving of Tropical High Clouds
Using satellite cloud data from the Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) and collocated precipitation rates from the Advanced Microwave Scanning Radiometer (AMSR), it is shown that rain rate is closely related to the amount ...
Terence L. Kubar; Dennis L. Hartmann; Robert Wood
Evolution of vertical drafts and cloud-to-ground lightning within the convective region of a mesoscale convective complex
The evolution of the area-averaged vertical velocity within the objectively defined convective region of the 4 June 1985 PRE-STORM (Preliminary Regional Experiment for Stormscale Operational and Research Meteorology-Central Phase) mesoscale convective complex (MCC) was examined over a 100 minute period during the storm's mature stage and compared to that of a squall line. The area-averaged vertical velocity profiles from twenty dual-Doppler analyses indicated significant differences in convective intensity both spatially and temporally. The peak magnitudes of the mid-to-upper level area-averaged vertical velocity were initially comparable to those from a squall line but became much weaker. The distribution of vertical velocities at mid-to-upper levels was consistent with weakening convection as the percentage of weak updrafts and downdrafts grew at the expense of stronger vertical motions. Typically the non-squall MCC had a much larger percentage of strong downdrafts than did the squall line. Horizontal and vertical cross-sections of both vertical velocity and reflectivity confirmed that the MCC was evolving toward a state with fewer and less intense updraft cores while cross-sections of storm relative flow revealed a descending rear-to-front inflow at later analysis times which reached the surface near locations of active convection. The relationship of cloud-to-ground (CG) lightning to the kinematic structure of the MCC was also studied. For mesoscale regions there was a 10-20 minute time lag between the peak convective intensity and the peak CG flash rate. A similar delay was found on the convective scale for some convective cells, however, other apparently similar cells had little CG lightning throughout their evolution. An analysis of the vertical profiles of the vertical velocity, reflectivity and their gradients above CG lightning suggested a preferred vertical structure of these fields for CG lightning. CG lightning occurred beneath greater than average vertical velocities at mid-to-upper levels and greater than average vertical velocity gradients and reflectivity at all levels. CG lightning also occurred beneath greater than average reflectivity gradients at mid and upper-levels but beneath smaller than average reflectivity gradients at low-levels due to its avoidance of the highest reflectivity gradient regions.
Saul, Scott Henry
A Deep Convection Event above the Tunuyán Valley near the Andes Mountains
Deep convection in the Tunuyán Valley region (33°–34°S, 69°–70°W) on the eastern side of the highest peaks of the Andes Mountains is sometimes associated with damaging hail. Understanding the physical mechanisms responsible for the occurrence of ...
A. de la Torre; V. Daniel; R. Tailleux; H. Teitelbaum
Observing Deep Convection in the Labrador Sea during Winter 1994/95
A 12-month mooring record (May 1994–June 1995), together with accompanying PALACE float data, is used to describe an annual cycle of deep convection and restratification in the Labrador Sea. The mooring is located at 56.75°N, 52.5°W, near the ...
Jonathan M. Lilly; Peter B. Rhines; Martin Visbeck; Russ Davis; John R. N. Lazier; Friedrich Schott; David Farmer
A Scale Analysis of Deep Moist Convection and Some Related Numerical Calculations
A scale analysis valid for deep moist convection is carried out. The approximate equations of motion are anelastic with the time scale set by the Brunt- Väisälä frequency. A new assumption is that the base state potential temperature is a slowly ...
Franik B. Lipps; Richard S. Hemler
Deep Convection East of the Andes Cordillera: A Test Case Analysis of Airmass Origin
Warm and moist air masses, required to generate deep convection east of the Andes Cordillera, are generally the result of humidity transport by the so-called low-level jet (LLJ). In this paper, it is shown from detailed test cases that the ...
Hector Teitelbaum; Hervé Le Treut; Mohamed Moustaoui; Gustavo C. Cabrera; Guillermo Ibańez
Characteristics of CALIPSO and CloudSat Backscatter at the Top Center Layers of Mesoscale Convective Systems and Relation to Cloud Microphysics
Following the discovery of anomalously high values of lidar integrated attenuated backscatter near the top center layers of mesoscale convective systems (MCSs) observed by the NASA Lidar In-Space Technology Experiment (LITE), a search of Cloud ...
C. M. R. Platt; M. A. Vaughan; R. T. Austin
Convection with Rotation in a Neutral Ocean: A Study of Open-Ocean Deep Convection
The intensity and scale of the geostrophically adjusted end state of the convective overturning of a homogeneous rotating ocean of depth H at a latitude where the Coriolis parameter is f, induced by surface buoyancy loss of magnitude B0, are ...
Interactions among Radiation, Convection, and Large-Scale Dynamics in a General Circulation Model
We have analyzed the effects of radiatively active clouds on the climate simulated by the UCLA/GLA GCM, with particular attention to the effects of the upper tropospheric stratiform clouds associated with deep cumulus convection, and the ...
David A. Randall; Harshvardhan; Donald A. Dazlich; Thomas G. Corsetti
Comparison between Observed Convective Cloud-Base Heights and Lifting Condensation Level for Two Different Lifted Parcels
Approximately 400 Automated Surface Observing System (ASOS) observations of convective cloud-base heights at 2300 UTC were collected from April through August of 2001. These observations were compared with lifting condensation level (LCL) heights ...
Jeffrey P. Craven; Ryan E. Jewell; Harold E. Brooks
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
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
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
Characteristics of Summer Convective Systems Initiated over the Tibetan Plateau. Part I: Origin, Track, Development, and Precipitation
Summer convective systems (CSs) initiated over the Tibetan Plateau identified by the International Satellite Cloud Climatology Project (ISCCP) deep convection database and associated Tropical Rainfall Measuring Mission (TRMM) precipitation for ...
Li Yaodong; Wang Yun; Song Yang; Hu Liang; Gao Shouting; Rong Fu
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.
The Structures of Summer Convective Clouds in Eastern Montana. I: Natural Clouds
The microstructures and precipitation-producing mechanisms in 93 clouds in the vicinity of Miles City, Montana have been explored through airborne measurements.
Peter V. Hobbs; Marcia K. Politovich; Lawrence F. Radke
A Two-Dimensional Numerical Investigation of the interaction between Sea Breezes and Deep Convection over the Florida Peninsula
Deep convection initiated by sea breezes over the Florida peninsula is simulated using a two-dimensional nonhydrostatic model. Reasonable agreement is obtained between model results and observations for the three types of undisturbed days ...
Melville E. Nicholls; Roger A. Pielke; William R. Cotton
Numerical Simulations of the Effect of Soil Moisture and Vegetation Cover on the Development of Deep Convection
A one-dimensional (column) version of a primitive equations model has been used to study the impact of soil moisture and vegetation cover on the development of deep cumulus convection in the absence of dynamical forcing. The model includes ...
Craig A. Clark; Paymond W. Arritt
Column Water Vapor Statistics and Their Relationship to Deep Convection, Vertical and Horizontal Circulation, and Moisture Structure at Nauru
Relationships among relatively high-frequency probability distribution functions (pdfs) of anomalous column water vapor (cwv), precipitating deep convection, and the vertical and horizontal structures of circulation and tropospheric moisture are ...
Benjamin R. Lintner; Christopher E. Holloway; J. David Neelin
Evolution of the Vertical Thermodynamic Profile during the Transition from Shallow to Deep Convection during CuPIDO 2006
The evolution of the vertical thermodynamic profile associated with two cases of deep orographic convection were studied with data from an instrumented aircraft, mobile surface based radiosondes, and stereo photogrammetric analyses. The data were ...
Joseph A. Zehnder; Jiuxiang Hu; Anshuman Radzan
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
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
Microphysics of Premonsoon and Monsoon Clouds as Seen from In Situ Measurements during the Cloud Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX)
Analysis of the microphysical structure of deep convective clouds using in situ measurements during the Cloud Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX) over the Indian peninsular region is presented. It is shown that ...
Thara V. Prabha; A. Khain; R. S. Maheshkumar; G. Pandithurai; J. R. Kulkarni; M. Konwar; B. N. Goswami
ARM tropical pacific experiment (ATPEX): Role of cloud, water vapor and convection feedbacks in the coupled ocean/atmosphere system
We have initiated studies that include radiation model validation, improved treatment of the three-dimensional structure of cloud-radiation interactions, and sensitivity runs that will unravel the role of cloud-convection-radiation interactions in the Pacific Sear Surface Temperatures and the overlying Walker and Hadley circulation. The research program is divided into three phases: (1) radiation, (2) cloud parameterization issues; (3) feedback and ocean-atmosphere interactions.
Ramanathan, V.; Barnett, T.P.
The Diurnal Cycle of the Boundary Layer, Convection, Clouds, and Surface Radiation in a Coastal Monsoon Environment (Darwin Australia)
The diurnal variation of convection and associated cloud and radiative properties remains a significant issue in global NWP and climate models. This study analyzes observed diurnal variability of convection in a coastal monsoonal environment examining the interaction of convective rain clouds, their associated cloud properties, and the impact on the surface radiation and corresponding boundary layer structure during periods where convection is suppressed or active on the large scale. The analysis uses data from the Tropical Warm Pool International Cloud Experiment (TWP-ICE) as well as routine measurements from the Australian Bureau of Meteorology and the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) program. Both active monsoonal and large-scale suppressed (buildup and break) conditions are examined and demonstrate that the diurnal variation of rainfall is much larger during the break periods and the spatial distribution of rainfall is very different between the monsoon and break regimes. During the active monsoon the total net radiative input to the surface is decreased by more than 3 times the amount than during the break regime - this total radiative cloud forcing is found to be dominated by the shortwave (SW) cloud effects because of the much larger optical thicknesses and persistence of long-lasting anvils and cirrus cloud decks associated with the monsoon regime. These differences in monsoon versus break surface radiative energy contribute to low-level air temperature differences in the boundary layer over the land surfaces.
May, Peter T.; Long, Charles N.; Protat, Alain
Deep Orographic Cloud Structure and Composition Derived from Comprehensive Remote Sensing Measurements
Coordinated polarization lidar, Ku-band radar and dual-channel microwave radiometer observations of a deep orographic cloud system were collected from a mountain-base site in northwestern Colorado as part of the Colorado Orographic Seeding ...
Kenneth Sassen
Aircraft Observations of Sub-cloud Aerosol and Convective Cloud Physical Properties
This research focuses on aircraft observational studies of aerosol-cloud interactions in cumulus clouds. The data were collected in the summer of 2004, the spring of 2007 and the mid-winter and spring of 2008 in Texas, central Saudi Arabia and Istanbul, Turkey, respectively. A set of 24 pairs of sub-cloud aerosol and cloud penetration data are analyzed. Measurements of fine and coarse mode aerosol concentrations from 3 different instruments were combined and fitted with lognormal distributions. The fit parameters of the lognormal distributions are compared with cloud droplet effective radii retrieved from 260 cloud penetrations. Cloud condensation nuclei (CCN) measurements for a subset of 10 cases from the Istanbul region are compared with concentrations predicted from aerosol size distributions. Ammonium sulfate was assumed to represent the soluble component of aerosol with dry sizes smaller than 0.5 mm and sodium chloride for aerosol larger than 0.5 mm. The measured CCN spectrum was used to estimate the soluble fraction. The correlations of the measured CCN concentration with the predicted CCN concentration were strong (R2 > 0.89) for supersaturations of 0.2, 0.3 and 0.6%. The measured concentrations were typically consistent with an aerosol having a soluble fraction between roughly 0.5 and 1.0, suggesting a contribution of sulfate or some other similarly soluble inorganic compound. The predicted CCN were found to vary by +or-3.7% when the soluble fraction was varied by 0.1. Cumulative aerosol concentrations at cutoff dry diameters of 1.1, 0.1 and 0.06 mm were found to be correlated with cloud condensation nuclei concentrations but not with maximum cloud base droplet concentrations. It is also shown that in some cases the predominant mechanisms involved in the formation of precipitation were altered and modified by the aerosol properties. This study suggests that CCN-forced variations in cloud droplet number concentration can change the effective radius profile and the type of precipitation hydrometeors. These differences may have a major impact on the global hydrological cycle and energy budget.
Axisa, Duncan
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
On the Observed Near Cancellation between Longwave and Shortwave Cloud Forcing in Tropical Regions
Observations based on Earth Radiation Budget Experiment (ERBE) satellite data indicate that there is a near cancellation between tropical longwave and shortwave cloud forcing in regions of deep convective activity. Cloud forcing depends on both ...
J. T. Kiehl
The Influence of the 1998 El Nińo upon Cloud-Radiative Forcing over the Pacific Warm Pool
Clouds cool the climate system by reflecting shortwave radiation and warm it by increasing the atmospheric greenhouse. Previous studies have shown that in tropical regions of deep convection there is a near cancellation between cloud-induced ...
Robert D. Cess; Minghua Zhang; Bruce A. Wielicki; David F. Young; Xue-Long Zhou; Yuri Nikitenko
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
A transilient matrix for moist convection
A method is introduced for diagnosing a transilient matrix for moist convection. This transilient matrix quantifies the nonlocal transport of air by convective eddies: for every height z, it gives the distribution of starting heights z{prime} for the eddies that arrive at z. In a cloud-resolving simulation of deep convection, the transilient matrix shows that two-thirds of the subcloud air convecting into the free troposphere originates from within 100 m of the surface. This finding clarifies which initial height to use when calculating convective available potential energy from soundings of the tropical troposphere.
Romps, D.; Kuang, Z.
ARM - Publications: Science Team Meeting Documents: The life stage of deep
The life stage of deep convection defined by the MSG multi-channel data and The life stage of deep convection defined by the MSG multi-channel data and rainfall type observed by PR/TRMM Inoue, Toshiro MRI/JMA The life cycle of deep convection is characterized as the cumulus/cumulonimbus type cloud classified by the method is dominant at the earlier stage and cirrus type cloud (anvil) is dominant at the decaying stage for no-split/no-merge case. We also know that convective rain is dominant at developing and mature stage, and stratiform rain is dominant at decaying stage. We studied the life cycle of deep convection in terms of cloud type using MSG ( Meteosat Second Generation) data taken every 15 minutes. The multi-channel data of MSG are use for cloud type classification. Cloud types are first classified by the split window method
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
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.
Nowcasting Convective Storm Initiation Using Satellite-Based Box-Averaged Cloud-Top Cooling and Cloud-Type Trends
Short-term (0–1 h) convective storm nowcasting remains a problem for operational weather forecasting, and convective storms pose a significant monetary sink for the aviation industry. Numerical weather prediction models, traditional ...
Justin M. Sieglaff; Lee M. Cronce; Wayne F. Feltz; Kristopher M. Bedka; Michael J. Pavolonis; Andrew K. Heidinger
Numerical Simulation of Organized Convection. Part I: Model Description and Preliminary Comparisons with Squall Line Observations
A numerical model designed for the simulations of mesoscale flows perturbed by deep convective clouds is discussed. It is based on the time dependent coupling between a three-dimensional nonhydrostatic mesoscale model and a quasi-one-dimensional ...
Yves Pointin
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
Sensitivity of a Cloud-Resolving Simulation of the Genesis of a Mesoscale Convective System to Horizontal Heterogeneities in Soil Moisture Initialization
This study examines the sensitivity of varying the horizontal heterogeneities of the soil moisture initialization (SMI) in the cloud-resolving grid of a real-data simulation of a midlatitude mesoscale convective system (MCS) during its genesis ...
William Y. Y. Cheng; William R. Cotton
Diurnal Variations and Modulation by Easterly Waves of the Size Distribution of Convective Cloud Clusters over West Africa and the Atlantic Ocean
Using Metecosat satellite data in the atmospheric infrared window, the authors study short time-scale fluctuations of the size distribution of tropical convective cloud clusters for July to September 1989. A cluster at a given brightness-...
L. A. Toledo Machado; J-Ph Duvel; M. Desbois
Patterns of Cloud-to-Ground Lightning and Convective Rainfall Associated with Postwildfire Flash Floods and Debris Flows in Complex Terrain of the Western United States
Flash flood and debris flow reports from Storm Data and the U.S. Geological Survey (USGS) are used to investigate the relationship between hazardous hydrological responses, convective rainfall, and cloud-to-ground (CG) lightning flash parameters. ...
S. Jeffrey Underwood; Michael D. Schultz
Polarization diversity for millimeter space-borne Doppler radars: an answer for observing deep convection?
Spaceborne Doppler radars have the potential to provide key missing observations of convective vertical air motions especially over the tropical oceans. Such measurements can improve our understanding of the role of tropical convection in vertical ...
Alessandro Battaglia; Simone Tanelli; Pavlos Kollias
Entrainment and the Temporal Development of the Microphysies of Convective Clouds
This paper addresses the question of time changes in the cloud parcels comprising a cumulus cloud. Observations are analyzed which show how a cloud parcel begins its life on the upshear side of the cloud. As the cloud as a whole continues to ...
David P. Rogers; James W. Telford; Steven K. Chai
Evolution of cloud-to-ground lightning characteristics within the convective region of a midlatitude squall line
The relationship between storm dynamics and cloud-to-ground (CG) lightning characteristics in the convective region of the 10-11 June 1985 PRE-STORM (Preliminary Regional Experiment for Stormscale Operational and Research Meteorology) squall line has been examined over a period of 49 minutes. Lightning data from the National Severe Storms Laboratory lightning detection network combined with seven dual-Doppler analyses provided a unique dataset in which to study this Mesoscale Convective System (MCS). The mature phase of this system passed through the dual-Doppler analysis domain during a period when the convective region made an apparent transition to a weaker convective state. For the overall system, the peak in flash rates was shown to lag the maximum in the vertical velocity by roughly 1 0 to 20 minutes. Cross-sectional analyses revealed numerous examples of this time lag along with a coincidence of descending mid-toupper level reflectivity features and increasing CG flash rates. Along-line dynamical differences in the convective region may have contributed to significant spatial variations in the flash rate. The northern portion of the line featured stronger, more continuous updrafts along with a relative sparseness of lightning strikes. The southern section displayed weaker, but more discrete cell evolution which coincided with a rather uniform and substantial number of CG strikes.
Billingsley, David Brian
Diurnal Cycle of Shallow and Deep Convection for a Tropical Land and an Ocean Environment and Its Relationship to Synoptic Wind Regimes
The characteristics of shallow and deep convection during the Tropical Rainfall Measuring Mission/Large-Scale Biosphere–Atmosphere Experiment in Amazonia (TRMM/LBA) and the Eastern Pacific Investigation of Climate Processes in the Coupled Ocean–...
L. Gustavo Pereira; Steven A. Rutledge
Precipitation and Evolution Sensitivity in Simulated Deep Convective Storms: Comparisons between Liquid-Only and Simple Ice and Liquid Phase Microphysics
Weisman and Klemp suggested that their liquid-only, deep convective storm experiments should be repeated with a liquid-ice microphysics scheme to determine if the solutions are qualitatively the same. Using a three-dimensional, nonhydrostatic ...
Matthew S. Gilmore; Jerry M. Straka; Erik N. Rasmussen
A Pronounced Upper-Tropospheric Warm Anomaly Encountered by the NOAA G-IV Aircraft in the Vicinity of Deep Convection
Recent flights near deep convection by the National Oceanic and Atmospheric Administration's Gulfstream-IV surveillance aircraft have occasionally experienced significant positive temperature anomalies that sometimes impact the aircraft ...
Robert Rogers; Sim Aberson; John Kaplan; Stan Goldenberg
Life Cycle Characteristics of Deep Cloud Systems over the Indian Region Using INSAT-1B Pixel Data
A detailed study of deep cloud systems (denoted by CSs) over the Indian region using INSAT-1B pixel data is presented. The life cycle characteristics of CSs are examined, including their preferred regions of formation and dissipation, frequency ...
Arvind V. Gambheer; G. S. Bhat
Sensitivity of Tropical Pacific Convection to Dry Layers at Mid- to Upper Levels: Simulation and Parameterization Tests
Numerical forecast experiments are carried out to investigate the implications of observed moisture variability in the tropical Pacific for deep convection. The study uses a series of quasi-cloud-resolving model forecasts with a triple-nested ...
James A. Ridout
ARM tropical pacific experiment (ATPEX): Role of cloud, water vapor and convection feedbacks in the coupled ocean/atmosphere system. Progress report, September 1, 1991--August 31, 1992
ARM - Midlatitude Continental Convective Clouds - Ultra High Sensitivity Aerosol Spectrometer(tomlinson-uhsas)
Ultra High Sensitivity Aerosol Spectrometer (UHSASA) A major component of the Mid-latitude Continental Convective Clouds Experiment (MC3E) field campaign was the deployment of an enhanced radiosonde array designed to capture the vertical profile of atmospheric state variables (pressure, temperature, humidity wind speed and wind direction) for the purpose of deriving the large-scale forcing for use in modeling studies. The radiosonde array included six sites (enhanced Central Facility [CF-1] plus five new sites) launching radiosondes at 3-6 hour sampling intervals. The network will cover an area of approximately (300)2 km2 with five outer sounding launch sites and one central launch location. The five outer sounding launch sites are: S01 Pratt, KS [ 37.7oN, 98.75oW]; S02 Chanute, KS [37.674, 95.488]; S03 Vici, Oklahoma [36.071, -99.204]; S04 Morris, Oklahoma [35.687, -95.856]; and S05 Purcell, Oklahoma [34.985, -97.522]. Soundings from the SGP Central Facility during MC3E can be retrieved from the regular ARM archive. During routine MC3E operations 4 radiosondes were launched from each of these sites (approx. 0130, 0730, 1330 and 1930 UTC). On days that were forecast to be convective up to four additional launches were launched at each site (approx. 0430, 1030, 1630, 2230 UTC). There were a total of approximately 14 of these high frequency launch days over the course of the experiment. These files contain brightness temperatures observed at Purcell during MC3E. The measurements were made with a 5 channel (22.235, 23.035, 23.835, 26.235, 30.000GHz) microwave radiometer at one minute intervals. The results have been separated into daily files and the day of observations is indicated in the file name. All observations were zenith pointing. Included in the files are the time variables base_time and time_offset. These follow the ARM time conventions. Base_time is the number seconds since January 1, 1970 at 00:00:00 for the first data point of the file and time_offset is the offset in seconds from base_time.
Jason Tomlinson; Mike Jensen
ARM - Midlatitude Continental Convective Clouds Microwave Radiometer Profiler (jensen-mwr)
A major component of the Mid-latitude Continental Convective Clouds Experiment (MC3E) field campaign was the deployment of an enhanced radiosonde array designed to capture the vertical profile of atmospheric state variables (pressure, temperature, humidity wind speed and wind direction) for the purpose of deriving the large-scale forcing for use in modeling studies. The radiosonde array included six sites (enhanced Central Facility [CF-1] plus five new sites) launching radiosondes at 3-6 hour sampling intervals. The network will cover an area of approximately (300)2 km2 with five outer sounding launch sites and one central launch location. The five outer sounding launch sites are: S01 Pratt, KS [ 37.7oN, 98.75oW]; S02 Chanute, KS [37.674, 95.488]; S03 Vici, Oklahoma [36.071, -99.204]; S04 Morris, Oklahoma [35.687, -95.856]; and S05 Purcell, Oklahoma [34.985, -97.522]. Soundings from the SGP Central Facility during MC3E can be retrieved from the regular ARM archive. During routine MC3E operations 4 radiosondes were launched from each of these sites (approx. 0130, 0730, 1330 and 1930 UTC). On days that were forecast to be convective up to four additional launches were launched at each site (approx. 0430, 1030, 1630, 2230 UTC). There were a total of approximately 14 of these high frequency launch days over the course of the experiment. These files contain brightness temperatures observed at Purcell during MC3E. The measurements were made with a 5 channel (22.235, 23.035, 23.835, 26.235, 30.000GHz) microwave radiometer at one minute intervals. The results have been separated into daily files and the day of observations is indicated in the file name. All observations were zenith pointing. Included in the files are the time variables base_time and time_offset. These follow the ARM time conventions. Base_time is the number seconds since January 1, 1970 at 00:00:00 for the first data point of the file and time_offset is the offset in seconds from base_time.
Mike Jensen
Nowcasting Thunderstorm Anvil Clouds over Kennedy Space Center and Cape Canaveral Air Force Station
Electrified thunderstorm anvil clouds extend the threat of natural and triggered lightning to space launch and landing operations far beyond the immediate vicinity of thunderstorm cells. The deep convective updrafts of thunderstorms transport ...
David A. Short; James E. Sardonia; Winifred C. Lambert; Mark M. Wheeler
A PDF-Based Microphysics Parameterization for Simulation of Drizzling Boundary Layer Clouds
Formulating the contribution of subgrid-scale (SGS) variability to microphysical processes in boundary layer and deep convective cloud parameterizations is a challenging task because of the complexity of microphysical processes and the lack of ...
Anning Cheng; Kuan-Man Xu
Response of Tropical Clouds to the Interannual Variation of Sea Surface Temperature
Connections between the large-scale interannual variations of clouds, deep convection, atmospheric winds, vertical thermodynamic structure, and SSTs over global tropical oceans are examined over the period July 1983-December 1990. The SST warming ...
Rong Fu; W. Timothy Liu; Robert E. Dickinson
The Effect of Environmental Conditions on Tropical Deep Convective Systems Observed from the TRMM Satellite
This study uses measurements of radiation and cloud properties taken between January and August 1998 by three Tropical Rainfall Measuring Mission (TRMM) instruments, the Clouds and the Earth's Radiant Energy System (CERES) scanner, the TRMM ...
Bing Lin; Bruce A. Wielicki; Patrick Minnis; Lin Chambers; Kuan-Man Xu; Yongxiang Hu; Alice Fan
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
Gravity Waves, Compensating Subsidence and Detrainment around Cumulus Clouds
Gravity waves play an important role in the redistribution of heat and moisture in a deep convecting cloud field. We explore this role in a two-dimensional numerical experiment on a simple moist convecting system consisting of an isolated long-...
Christopher S. Bretherton; Piotr K. Smolarkiewicz
Assessing the Potential for Rain Augmentation?The Nelspruit Randomized Convective Cloud Seeding Experiment
The experimental design, analyses, and results of the first Nelspruit randomized cloud seeding experiment are described. The experiment ran for three years, commencing in October 1984, and involved the on-top seeding of new cloud turrets growing ...
G. K. Mather; M. J. Dixon; J. M. de Jager
The Structures of Summer Convective Clouds in Eastern Montana. II: Effects of Artificial Seeding
The seeding of clouds in Miles City, Montana with AgI pyrotechnics at cloud tops generally produced large increases in ice particle concentrations, decreases in liquid water contents, and increases in precipitation particles lower down in the ...
Peter V. Hobbs; Marcia K. Politovich
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
The cloud condensation nuclei and ice nuclei effects on tropical anvil characteristics and water vapor of the tropical tropopause layer
Cloud anvils from deep convective clouds are of great importance to the radiative energy budget and the aerosol impact on them is the least understood. Few studies examined the effects of both cloud condensation nuclei (CCN) and ice nuclei (IN) on anvil properties and water vapor content (WVC) in the Tropical Tropopause Layer (TTL). Using a 3-dimensional cloud-resolving model with size-resolved cloud microphysics, we focus on the CCN and IN effects on cloud anvil properties and WVC in the TTL. We find that cloud microphysical changes induced by CCN/IN play a very important role in determining cloud anvil area and WVC in the TTL, whether convection is enhanced or suppressed. Also, CCN effects on anvil microphysical properties, anvil size and lifetime are much more evident relative to IN. IN has little effect on convection, but can increase ice number and mass concentrations significantly under humid conditions. CCN in the PBL is found to have greater effects on convective strength and mid-tropospheric CCN has negligible effects on convection and cloud properties. Convective transport may only moisten the main convective outflow region but the cloud anvil size determines the WVC in the TTL domain. This study shows an important role of CCN in the lower-troposphere in modifying convection, the upper-level cloud properties. It also shows the effects of IN and the PBL CCN on the upper-level clouds depends on the humidity, resolving some contradictory results in past studies. 2
Fan, Jiwen; Comstock, Jennifer M.; Ovchinnikov, Mikhail
Role of Gravity Waves in Triggering Deep Convection during TOGA COARE
The role of gravity waves in the initiation of convection over oceanic regions during the Tropical Ocean Global Atmosphere Coupled Ocean–Atmosphere Response Experiment (TOGA COARE) experiment is investigated. First, an autocorrelation method is ...
C. Lac; J-P. Lafore; J-L. Redelsperger
The Gravity Wave Response above Deep Convection in a Squall Line Simulation
High-frequency gravity waves generated by convective storms likely play an important role in the general circulation of the middle atmosphere. Yet little is known about waves from this source. This work utilizes a fully compressible, nonlinear, ...
M. J. Alexander; J. R. Holton; D. R. Durran
Tracer Transport in Deep Convective Updrafts: Plume Ensemble versus Bulk Formulations
Two widely used approaches for parameterizing tracer transport based on convective mass fluxes are the plume ensemble formulation (PEF) and the bulk formulation (BF). Here the behavior of these two is contrasted for the specific case in which the ...
Mark G. Lawrence; Philip J. Rasch
Impacts of Land–Atmosphere Feedbacks on Deep, Moist Convection on the Canadian Prairies
The purpose of this study was to focus on how anomalies in the normalized difference vegetation index (NDVI; a proxy for soil moisture) over the Canadian Prairies can condition the convective boundary layer (CBL) so as to inhibit or facilitate ...
Julian C. Brimelow; John M. Hanesiak; William R. Burrows
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
The Influence of Time-Dependent Melting on the Dynamics and Precipitation Production in Maritime and Continental Storm Clouds
Simulations of one maritime and four continental observed cases of deep convection are performed with the Hebrew University Cloud Model that has spectral bin microphysics. The maritime case is from observations made on 18 September 1974 during ...
Vaughan T. J. Phillips; Andrei Pokrovsky; Alexander Khain
Convective cloud and rainfall processes over the Maritime Continent : simulation and analysis of the diurnal cycle
The Maritime Continent experiences strong moist convection, which produces significant rainfall and drives large fluxes of heat and moisture to the upper troposphere. Despite the importance of these processes to global ...
Gianotti, Rebecca L. (Rebecca Louise)
Estimating the Orientation and Spacing of Midlatitude Linear Convective Boundary Layer Features: Cloud Streets
Linear features in a clear convective boundary layer (CBL) over the North Atlantic Ocean were studied during a weak cold air outbreak using a down-looking airborne lidar. Sequential lidar profiles were placed together and color coded to provide ...
S. H. Melfi; Stephen P. Palm
Cloud-Resolving Simulations of Mesoscale Vortex Intensification and Its Effect on a Serial Mesoscale Convective System
The authors performed numerical simulations of the 27–28 May 1998 mesoscale convective vortex (MCV) and mesoscale convective system (MCS) to understand how the MCV modulated the convection, and how the convection intensified the vortex. The fifth-...
Christopher A. Davis; Stanley B. Trier
Synoptic Forcing and Control of Deep Convection on Day 261 of GATE
An evolutionary view is sought Of a single cloud cluster. This cluster was chosen less for intensity than for comprehensive observations. The aim is to describe the principal outside controls on the cluster, including its relationship with nearby ...
David W. Martin; Brian Auvine; David Suchman
An Energy-Balance Analysis of Deep Convective Self-Aggregation above Uniform SST
-aggregation is sensitive to the ice microphysical parameterization, which affects the location and extent of cirrus clouds the dry to the moist regions. A simple mathematical model of the initial phase of self
Bretherton, Chris
A Unified Representation of Deep Moist Convection in Numerical Modeling of the Atmosphere. Part I
A generalized framework for cumulus parameterization applicable to any horizontal resolution between those typically used in general circulation and cloud-resolving models is presented. It is pointed out that the key parameter in the ...
Akio Arakawa; Chien-Ming Wu
Lagrangian Diagnostics of Tropical Deep Convection and Its Effect upon Upper-Tropospheric Humidity
This study combines geostationary water vapor imagery with optical cloud property retrievals and microwave sea surface observations in order to investigate, in a Lagrangian framework, (i) the importance of cirrus anvil sublimation on tropical ...
Ákos Horváth; Brian J. Soden
Evaluation of tropical cloud and precipitation statistics of CAM3 using CloudSat and CALIPSO data
The combined CloudSat and CALIPSO satellite observations provide the first simultaneous measurements of cloud and precipitation vertical structure, and are used to examine the representation of tropical clouds and precipitation in the Community Atmosphere Model Version 3 (CAM3). A simulator package utilizing a model-to-satellite approach facilitates comparison of model simulations to observations, and a revised clustering method is used to sort the subgrid-scale patterns of clouds and precipitation into principal cloud regimes. Results from weather forecasts performed with CAM3 suggest that the model underestimates the horizontal extent of low and mid-level clouds in subsidence regions, but overestimates that of high clouds in ascending regions. CAM3 strongly overestimates the frequency of occurrence of the deep convection with heavy precipitation regime, but underestimates the horizontal extent of clouds and precipitation at low and middle levels when this regime occurs. This suggests that the model overestimates convective precipitation and underestimates stratiform precipitation consistent with a previous study that used only precipitation observations. Tropical cloud regimes are also evaluated in a different version of the model, CAM3.5, which uses a highly entraining plume in the parameterization of deep convection. While the frequency of occurrence of the deep convection with heavy precipitation regime from CAM3.5 forecasts decreases, the incidence of the low clouds with precipitation and congestus regimes increases. As a result, the parameterization change does not reduce the frequency of precipitating convection that is far too high relative to observations. For both versions of CAM, clouds and precipitation are overly reflective at the frequency of the CloudSat radar and thin clouds that could be detected by the lidar only are underestimated.
Zhang, Y; Klein, S; Boyle, J; Mace, G G
Drop Size Separation in Numerically Simulated Convective Clouds and Its Effect on Warm Rain Formation
It is shown that, as a result of the flow diffluence at the upper levels of the cloud, droplets of different sizes move along different trajectories. The small droplets with negligible fall velocities will have higher probability of being carried ...
Daytime Cycle of Low-Level Clouds and the Tropical Convective Boundary Layer in Southwestern Amazonia
During the wet season in the southwestern Amazon region, daytime water transport out of the atmospheric mixed layer into the deeper atmosphere is shown to depend upon cloud amounts and types and synoptic-scale velocity fields. Interactions among ...
C. Strong; J. D. Fuentes; M. Garstang; A. K. Betts
Spatial Variability of Liquid Water Path in Marine Low Cloud: The Importance of Mesoscale Cellular Convection
Liquid water path (LWP) mesoscale spatial variability in marine low cloud over the eastern subtropical oceans is examined using two months of daytime retrievals from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the NASA Terra ...
Robert Wood; Dennis L. Hartmann
Wavelet Analysis of Simulated Tropical Convective Cloud Systems. Part I: Basic Analysis
A wavelet analysis of a three-dimensional 7-day explicit simulation of the tropical cloud systems in the Global Atmosphere Research Programme (GARP) Atlantic Tropical Experiment Phase III is performed. Three physically distinct regimes (squall ...
Jun-Ichi Yano; Mitchell W. Moncrieff; Xiaoqing Wu; Michio Yamada
A Dual Mass Flux Framework for Boundary Layer Convection. Part II: Clouds
This paper presents the extension of the eddy diffusivity mass flux (EDMF) framework for turbulent transport into the statistical modeling of boundary layer clouds. The advection–diffusion decomposition that defines EDMF is projected onto the ...
Roel A. J. Neggers
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
Evolution of Severe and Non-severe Convection Inferred from GOES-derived Cloud Properties
Geostationary satellites (e.g. Geostationary Operational Environmental Satellite [GOES]) provide high temporal resolution of cloud development and motion, which is essential to the study of many mesoscale phenomena, including thunderstorms. ...
John L. Cintineo; Michael J. Pavolonis; Justin M. Sieglaff; Andrew K. Heidinger
Multiscale Organization of Convection Simulated with Explicit Cloud Processes on an Aquaplanet
This study investigated the multiscale organization of tropical convection on an aquaplanet in a model experiment with a horizontal mesh size of 3.5 km (for a 10-day simulation) and 7 km (for a 40-day simulation). The numerical experiment used ...
Tomoe Nasuno; Hirofumi Tomita; Shinichi Iga; Hiroaki Miura; Masaki Satoh
A Z-R Relation for Summertime Convective Clouds over West Texas
A set of Z-R relations is derived by linear regression for summertime convective rainfall in West Texas from data gathered with an SWR-75 weather radar and a network of weighing bucket raingages. Data from 21 storms were grouped into storm were ...
Eric A. Pani; Gerald M. Jurica
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
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
Scale Selection in Locally Forced Convective Fields and the Initiation of Deep Cumulus
Deep cumulus dynamics has often been treated as an initial value problem where the long time effect of surface energy fluxes are neglected. Initiation is often assumed to follow from a strong localized deformation of the flow field, which is ...
V. Balaji; Terry L. Clark
Remote Trigger of Deep Convection by Cold Outflow over the Taiwan Strait in the Mei-Yu Season: A Modeling Study of the 8 June 2007 Case
In this study, the heavy-rainfall event over central Taiwan during the mei-yu season on 8 June 2007 is investigated, with an emphasis on the triggering mechanism for the deep convection that produced the rain. Observations indicate that there ...
Chung-Chieh Wang; George Tai-Jen Chen; Shin-Yi Huang
Global Distribution of Tropical Deep Convection: Different Perspectives from TRMM Infrared and Radar Data
Cold cloud features (CCFs) are defined by grouping six full years of Tropical Rainfall Measuring Mission (TRMM) infrared pixels with brightness temperature at 10.8-?m wavelength (TB11) less than or equal to 210 and 235 K. Then the precipitation ...
Chuntao Liu; Edward J. Zipser; Stephen W. Nesbitt
Modeling the Impact of Convective Entrainment on the Tropical Tropopause
Simulations with the Weather Research and Forecasting (WRF) cloud-resolving model of deep moist convective events reveal net cooling near the tropopause (15–18 km above ground), caused by a combination of large-scale ascent and small-scale ...
F. J. Robinson; S. C. Sherwood
Life Cycle Variations of Mesoscale Convective Systems over the Americas
Using GOES-7 ISCCP-B3 satellite data for 1987–88, the authors studied the evolution of the morphological and radiative properties of clouds over the life cycles of deep convective systems (CS) over the Americas at both tropical and middle ...
L. A. T. Machado; W. B. Rossow; R. L. Guedes; A. W. Walker
Cloud Interactions and Merging: Numerical Simulations
A total of 48 numerical experiments have been performed to study cloud interactions and merging by means of a two-dimensional multi-cell model. Two soundings of deep convection during GATE and two different magnitudes of large-scale lifting.have ...
Wei-Kuo Tao; Joanne Simpson
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 &
A Theoretical Study of the Wet Removal of Atmospheric Pollutants. Part V: The Uptake, Redistribution, and Deposition of (NM4)4SO4 by a Convective Cloud Containing Ice
The effects of an ice phase on the wet deposition of aerosol particles was studied by means of the authors' 2D cloud dynamics model with spectral microphysics applied to the Cooperative Convective Precipitation Experiment in Miles City, Montana, ...
Petra S. Respondek; A. I. Flossmann; R. R. Alheit; H. R. Pruppacher
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
Deep Convective Systems Observed by A-Train in the Tropical Indo-Pacific Region Affected by the MJO
In the Indo-Pacific region, mesoscale convective systems (MCSs) occur in a pattern consistent with the eastward propagation of the large-scale convective envelope of the Madden–Julian oscillation (MJO). MCSs are major contributors to the total ...
Jian Yuan; Robert A. Houze Jr.
ARM - Midlatitude Continental Convective Clouds Experiment (MC3E): Multi-Frequency Profilers, Surface Meteorology (williams-surfmet)
This data was collected by the NOAA 449-MHz and 2.8-GHz profilers in support of the Department of Energy (DOE) and NASA sponsored Mid-latitude Continental Convective Cloud Experiment (MC3E). The profiling radars were deployed in Northern Oklahoma at the DOE Atmospheric Radiation Mission (ARM) Southern Great Plans (SGP) Central Facility from 22 April through 6 June 2011. NOAA deployed three instruments: a Parsivel disdrometer, a 2.8-GHz profiler, and a 449-MHz profiler. The parasivel provided surface estimates of the raindrop size distribution and is the reference used to absolutely calibrate the 2.8 GHz profiler. The 2.8-GHz profiler provided unattenuated reflectivity profiles of the precipitation. The 449-MHz profiler provided estimates of the vertical air motion during precipitation from near the surface to just below the freezing level. By using the combination of 2.8-GHz and 449-MHz profiler observations, vertical profiles of raindrop size distributions can be retrieved. The profilers are often reference by their frequency band: the 2.8-GHz profiler operates in the S-band and the 449-MHz profiler operates in the UHF band. The raw observations are available as well as calibrated spectra and moments. This document describes how the instruments were deployed, how the data was collected, and the format of the archived data.
Christopher Williams; Mike Jensen
ARM - Midlatitude Continental Convective Clouds Experiment (MC3E): Multi-Frequency Profilers, Vertical Air Motion (williams-vertair)
ARM - Midlatitude Continental Convective Clouds Experiment (MC3E): Multi-Frequency Profilers, Parcivel Disdrometer (williams-disdro)
ARM - Midlatitude Continental Convective Clouds Experiment (MC3E): Multi-Frequency Profilers, 449 MHz Profiler(williams-449_prof)
Large-Scale Parallel Computing of Cloud Resolving Storm Simulator
A sever thunderstorm is composed of strong convective clouds. In order to perform a simulation of this type of storms, a very finegrid system is necessary to resolve individual convective clouds within a large domain. Since convective clouds are highly ...
Kazuhisa Tsuboki; Atsushi Sakakibara
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: firstname.lastname@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
The Convective Storm Initiation Project
The Convective Storm Initiation Project (CSIP) is an international project to understand precisely where, when, and how convective clouds form and develop into showers in the mainly maritime environment of southern England. A major aim of CSIP is ...
Keith A. Browning; Cyril J. Morcrette; John Nicol; Alan M. Blyth; Lindsay J. Bennett; Barbara J. Brooks; John Marsham; Stephan D. Mobbs; Douglas J. Parker; Felicity Perry; Peter A. Clark; Sue P. Ballard; Mark A. Dixon; Richard M. Forbes; Humphrey W. Lean; Zhihong Li; Nigel M. Roberts; Ulrich Corsmeier; Christian Barthlott; Bernhard Deny; Norbert Kalthoff; Samiro Khodayar; Martin Kohler; Christoph Kottmeier; Stephan Kraut; Michael Kunz; Jürgen Lenfant; Andreas Wieser; Judith L. Agnew; Dave Bamber; James McGregor; Karl M. Beswick; Malcolm D. Gray; Emily Norton; Hugo M. A. Ricketts; Andrew Russell; Geraint Vaughan; Ann R. Webb; Mark Bitter; Thomas Feuerle; Rolf Hankers; Helmut Schulz; Karen E. Bozier; Chris G. Collier; Fay Davies; Catherine Gaffard; Tim J. Hewison; Darcy N. Ladd; Elizabeth C. Slack; Joe Waight; Markus Ramatschi; David P. Wareing; Robert J. Watson
Effects of Downdrafts and Mesoscale Convective Organization on the Heat and Moisture Budgets of Tropical Cloud Clusters. Part II: Effects of Convective-Scale Downdrafts
The diagnostic cumulus ensemble model presented in Part I of this paper is applied to the data taken during Phase III of the GARP Tropical Atlantic Experiment (GATE) to examine the effects of convective-scale downdrafts on the large-scale heat ...
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
Cloud-to-Ground Lightning Production in Strongly Forced, Low-Instability Convective Lines Associated with Damaging Wind
During 9–11 November 1998 and 9–10 March 2002, two similar convective lines moved across the central and eastern United States. Both convective lines initiated over the southern plains along strong surface-based cold fronts in moderately unstable ...
Matthew S. van den Broeke; David M. Schultz; Robert H. Johns; Jeffry S. Evans; John E. Hales
Monsoon Environment (Darwin, Australia) PETER T. MAY Centre for Australian Weather and Climate Research variability of convection in a coastal monsoonal environment examining the interaction of convective rain Measurement (ARM) program. Both active monsoonal and large-scale suppressed (buildup and break) conditions
Protat, Alain
The Role of Small Soluble Aerosols in the Microphysics of Deep Maritime Clouds
Some observational evidence—such as bimodal drop size distributions, comparatively high concentrations of supercooled drops at upper levels, high concentrations of small ice crystals in cloud anvils leading to high optical depth, and lightning in ...
A. P. Khain; V. Phillips; N. Benmoshe; A. Pokrovsky
Observations of Deep Convection in the Gulf of Lions, Northern Mediterranean, during the Winter of 1991/92
During December 1991 to April 1992 measurements with moored acoustic Doppler current profiler (ADCP) stations and shipboard surveys were carried out in the convection regime of the Gulf of Lions, northwestern Mediterranean. First significant ...
Friedrich Schott; Martin Visbeck; Uwe Send; Jürgen Fischer; Lothar Stramma; Yves Desaubies
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...
The Use of Cloud-Resolving Simulations of Mesoscale Convective Systems to Build a Mesoscale Parameterization Scheme
A method is described for parameterizing thermodynamic forcing by the mesoscale updrafts and downdrafts of mesoscale convective systems (MCSs) in models with resolution too coarse to resolve these drafts. The parameterization contains ...
G. David Alexander; William R. Cotton
Squall Lines and Convectively Coupled Gravity Waves in the Tropics: Why Do Most Cloud Systems Propagate Westward?
The coupling between tropical convection and zonally propagating gravity waves is assessed through Fourier analysis of high-resolution (3-hourly, 0.5°) satellite rainfall data. Results show the familiar enhancement in power along the dispersion ...
Stefan N. Tulich; George N. Kiladis
A New Parameterization for Shallow Cumulus Convection and Its Application to Marine Subtropical Cloud-Topped Boundary Layers. Part II: Regional Simulations of Marine Boundary Layer Clouds
The impact of physical parameterizations on simulations of cloud-topped marine boundary layers is investigated using the fifth-generation Pennsylvania State University–NCAR Mesoscale Model (MM5). Three-month MM5 simulations of the northeast and ...
James R. McCaa; Christopher S. Bretherton
Evaluating the Performance of Planetary Boundary Layer and Cloud Microphysical Parameterization Schemes in Convection-Permitting Ensemble Forecasts using
uncertainty in how to include various processes (e.g., drop breakup and ice-phase categories 1 Evaluating the Performance of Planetary Boundary Layer and Cloud Microphysical Parameterization In this study, the ability of several cloud microphysical and planetary boundary layer parameterization schemes
Xue, Ming
The Vertical Structure of Tropical Convection and Its Impact on the Budgets of Water Vapor and Ozone
Convective clouds in the Tropics that penetrate the boundary layer inversion preferentially detrain into a shallow outflow layer (2–5 km) or a deep outflow layer (10–17 km). The properties of these layers are diagnosed from a one-dimensional ...
Ian Folkins; Randall V. Martin
Aircraft Microwave Observations and Simulations of Deep Convection from 18 to 183 GHz. Part II: Model Results
In Part II of the 29 June 1986 case study, a radiative transfer model is used to simulate the aircraft multichannel microwave brightness temperatures presented in Part I and to study the convective storm structure. Ground-based radar data are ...
Hwa-Young M. Yeh; N. Prasad; Robert A. Mack; Robert F. Adler
Recent Changes in Cloud-Type Frequency and Inferred Increases in Convection over the United States and the Former USSR
Significant changes and a general redistribution in the frequencies of various cloud types have been observed during the past 40–50 years over the midlatitude land areas of the Northern Hemisphere. This is evident for North America and northern ...
Bomin Sun; Pavel Ya Groisman; Igor I. Mokhov
Radiative Effects of Cloud Inhomogeneity and
cloud-overlap assumptions and optical property approximations (Del Genio et al. 1996; Fowler and Randall 1996; Liang and Wang 1997). While GCMs require convection and cloud...
A 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
Tropical Warm Pool International Cloud Experiment (TWP-ICE): Cloud and Rain Characteristics in the Australian Monsoon
The impact of oceanic convection on its environment and the relationship between the characteristics of the convection and the resulting cirrus characteristics is still not understood. An intense airborne measurement campaign combined with an extensive network of ground-based observations is being planned for the region near Darwin, Northern Australia, during January-February, 2006, to address these questions. The Tropical Warm Pool – International Cloud Experiment (TWP-ICE) will be the first field program in the tropics that attempts to describe the evolution of tropical convection, including the large scale heat, moisture, and momentum budgets, while at the same time obtaining detailed observations of cloud properties and the impact of the clouds on the environment. The emphasis will be on cirrus for the cloud properties component of the experiment. Cirrus clouds are ubiquitous in the tropics and have a large impact on their environment but the properties of these clouds are poorly understood. A crucial product from this experiment will be a dataset suitable to provide the forcing and testing required by cloud-resolving models and parameterizations in global climate models. This dataset will provide the necessary link between cloud properties and the models that are attempting to simulate them. The experiment is a collaboration between the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Program, the Bureau of Meteorology (BoM), the National Aeronautics and Space Administration (NASA), the European Commission DG RTD-1.2, and several United States, Australian, Canadian, and European Universities. This experiment will be undertaken over a 4-week period in early 2006. January and February corresponds to the wet phase of the Australia monsoon. This season has been selected because, despite Darwin's coastal location, the convection that occurs over and near Darwin at this time is largely of maritime origin with a large fetch over water. Based on previous experiments, the convection appears typical of maritime convection with widespread convection that has complex organization, but is not as deep or as intense as continental or coastal convection. Therefore, it is expected that the convection and cloud characteristics will be representative of conditions typical for wide areas of the tropics.
PT May; C Jakob; JH Mather
Physics of Greenhouse Effect and Convection in Warm Oceans
Sea surface temperature (SST) in roughly 50% of the tropical Pacific Ocean is warm enough (SST > 300 K) to permit deep convection. This paper examines the effects of deep convection on the climatological mean vertical distributions of water vapor ...
A. K. Inamdar; V. Ramanathan
ARM - Midlatitude Continental Convective Clouds Experiment (MC3E): Multi-Frequency Profilers, S-band Radar (williams-s_band)
Christopher Williams
Tropical cloud properties as a function of regime Regimes? Monsoon versus Break * Different synoptic vertical velocity profiles - Changes convective inhibition, corresponding...
Supersaturation Intermittency in Turbulent Clouds
It is hypothesized that bursts of high supersaturation are produced in turbulent, convective clouds through interactions between cloud droplets and the small-scale structure of atmospheric turbulence. This hypothesis is based on the observation ...
Raymond A. Shaw
Physics of greenhouse effect and convection in warm Oceans
Sea surface temperatures (SST) in roughly 50% of the tropical Pacific Ocean is warm enough (SST > 300 K) to permit deep convection. This paper examines the effects of deep convection on the climatological mean vertical distributions of water vapor and its greenhouse effect over such warm oceans. The study also examines the link between SST, vertical distribution of water vapor, and its greenhouse effect in the tropical oceans. The radiation model calculations do not include the effects of clouds. The data are grouped into nonconvective and convective categories using SST as an index for convective activity. On average, convective regions are more humid, trap significantly more longwave radiation, and emit more radiation to the sea surface. The greenhouse effect in regions of convection operates as per classical ideas, that is, as the SST increases, the atmosphere traps the excess longwave energy emitted by the surface and reradiates it locally back to the ocean surface. The important departure from the classical picture is that the net (up minus down) fluxes at the surface and at the top-of-the atmosphere decrease with an increase in SST; that is, the surface and the surface-troposphere column lose the ability to radiate the excess energy to space. The cause of this upper greenhouse effect at the surface is the rapid increase in the lower-troposphere humidity with SST; that of the column is due to a combination of increase in humidity in the entire column and increase in the lapse rate within the lower troposphere. The increase in the vertical distribution of humidity far exceeds that which can be attributed to the temperature dependence of saturation vapor pressure; that is, the tropospheric relative humidity is larger in convective regions. The positive coupling between SST and the radiative warming of the surface by the water vapor greenhouse effect is also shown to exist on interannual time scales. 35 refs., 17 figs. 4 tabs.
Inamdar, A.K.; Ramanathan, V. (Univ. of California, San Diego, La Jolla, CA (United States))
Aircraft Microphysical Documentation from Cloud Base to Anvils of Hailstorm Feeder Clouds in Argentina
Documentation during January and February 2000 of the structure of severe convective storms in Mendoza, Argentina, with a cloud-physics jet aircraft penetrating the major feeder clouds from cloud base to the ?45°C isotherm level is reported. ...
Daniel Rosenfeld; William L. Woodley; Terrence W. Krauss; Viktor Makitov
Measurement of Cloud Perturbation Pressures Using an Instrumented Aircraft
Vertical accelerations during the early stages of convective cloud formation are often the result of buoyancy and the perturbation vertical pressure gradient forces. Convection modifies the local pressure field surrounding the cloud. Measurement ...
Thomas R. Parish; David Leon
Convective Inhibition as a Predictor of Convection during AVE-SESAME II
The AVE-SESAME 11 data set of 19 April 1979 is examined to determine the thermodynamic conditions prior to the onset of deep convection in western Kansas. The observations indicate that the convective region was characterized locally by ...
Frank P. Colby Jr.
Inertial Instability and Mesoscale Convective Systems. part II. Symmetric CISK in a Baroclinic Flow
Numerous budget studies of organized persistent systems of convective clouds outside the tropics suggest that circulations of mesoscale proportions are important in supplying moisture to the convective clouds, though the dynamical nature of ...
Kerry A. Emanuel
Dynamics of Orographically Triggered Banded Convection in Sheared Moist Orographic Flows
Shallow orographic convection embedded in an unstable cap cloud can organize into convective bands. Previous research has highlighted the important role of small-amplitude topographic variations in triggering and organizing banded convection. ...
Oliver Fuhrer; Christoph Schär
Characterization of Momentum Transport Associated with Organized Moist Convection and Gravity Waves
Tropical convection is inherently multiscalar, involving complex fields of clouds and various regimes of convective organization ranging from small disorganized cumulus up to large organized convective clusters. In addition to being a crucial ...
Todd P. Lane; Mitchell W. Moncrieff
Evaluating the Performance of Planetary Boundary Layer and Cloud Microphysical Parameterization Schemes in Convection-Permitting Ensemble Forecasts using Synthetic GOES-13 Satellite Observations
In this study, the ability of several cloud microphysical and planetary boundary layer parameterization schemes to accurately simulate cloud characteristics within 4-km-grid-spacing ensemble forecasts over the contiguous U.S. was evaluated through ...
Rebecca Cintineo; Jason A. Otkin; Ming Xue; Fanyou Kong
Retrieval of Thermal and Microphysical Variables in Observed Convective Storms. Part II: Sensitivity of Cloud Processes to Variation of the Microphysical Parameterization
The hydrometeor content and thermal fields in a thunderstorm are estimated from a three-dimensional kinematic cloud model employing Doppler wind fields and parameterized microphysical processes. The sensitivity of the cloud model calculations to ...
Conrad L. Ziegler
Convection in TOGA COARE: Horizontal Scale, Morphology, and Rainfall Production
The occurrence frequency and rainfall production of mesoscale convective systems (MCSs) relative to smaller groups of convective clouds over the tropical oceans is not well known. Eighty days of shipboard radar data collected during the recent ...
Thomas M. Rickenbach; Steven A. Rutledge
Modeling Study of a Tropical Squall-Type Convective Line
A multidimensional and time-dependent cloud scale model is used to investigate the dynamic and micro-physical processes associated with convective and stratiform regions within a tropical squall-type convective line. The evolution of the total ...
A Model to Determine Open or Closed Cellular Convection
A simple mechanism is proposed to help explain the observed presence in the atmosphere of open or closed cellular convection. If convection is produced by cooling concentrated near the top of the cloud layer, as in radiative cooling of stratus ...
H. Mark Helfand; Eugenia Kalnay
Simulation of Tropical Convective Systems. Part I: A Cumulus Parameterization
A new cumulus parametefization is developed for ffse in mesoscale model simulations of precipitating convective systems. It is designed to estimate convective properties using a cloud model that interacts with the mesoscale model in a physically ...
William M. Frank; Charles Cohen
BNL | Aerosol, Cloud, Precipitation Interactions
Cloud-Aerosol-Precipitation Interactions Cloud-Aerosol-Precipitation Interactions Atmospheric aerosols exert important "indirect effects" on clouds and climate by serving as cloud condensation nuclei (CCN) and ice nuclei that affect cloud radiative and microphysical properties. For example, an increase in CCN increases the number concentration of droplets enhances cloud albedo, and suppresses precipitation that alters cloud coverage and lifetime. However, in the case of moist and strong convective clouds, increasing aerosols may increase precipitation and enhance storm development. Although aerosol-induced indirect effects on climate are believed to have a significant impact on global climate change, estimating their impact continues to be one of the most uncertain climate forcings.
COPT 81: A Field Experiment Designed for the Study of Dynamics and Electrical Activity of Deep Convection in Continental Tropical Regions
During May and June 1981 several French research organizations, the University of Abidjan (Ivory coast) and the Agency for security of Aeronautical Navigation (ASECNA), participated in the observational field program called "Convection Profonde ...
Gilles Sommeria; J. Testud
A Numerical Study of Three-Dimensional Gravity Waves Triggered by Deep Tropical Convection and Their Role in the Dynamics of the QBO
A 3D mesoscale model is used to study the structure of convectively triggered gravity waves in the Tropics and their role in the dynamics of the middle atmosphere. Simulations with three stratospheric background zonal wind cases are examined. In ...
C. Piani; D. Durran; M. J. Alexander; J. R. Holton
Stratospheric Gravity Waves Generated by Multiscale Tropical Convection
The generation of gravity waves by multiscale cloud systems evolving in an initially motionless and thermodynamically uniform environment is explored using a two-dimensional cloud-system-resolving model. The simulated convection has similar depth ...
More Observations of Small Funnel Clouds and Other Tubular Clouds
In this brief contribution, photographic documentation is provided of a variety of small, tubular-shaped clouds and of a small funnel cloud pendant from a convective cloud that appears to have been modified by flow over high-altitude mountains in ...
The Atmospheric Energy Budget and Large-Scale Precipitation Efficiency of Convective Systems during TOGA COARE, GATE, SCSMEX, and ARM: Cloud-Resolving Model Simulations
A two-dimensional version of the Goddard Cumulus Ensemble (GCE) model is used to simulate convective systems that developed in various geographic locations (east Atlantic, west Pacific, South China Sea, and Great Plains in the United States). ...
W-K. Tao; D. Johnson; C-L. Shie; J. Simpson
Orogenic Convection in Subtropical South America as Seen by the TRMM Satellite
Extreme orogenic convective storms in southeastern South America are divided into three categories: storms with deep convective cores, storms with wide convective cores, and storms containing broad stratiform regions. Data from the Tropical ...
Kristen L. Rasmussen; Robert A. Houze Jr.
Analysis of Convectively Coupled Kelvin Waves in the Indian Ocean MJO
The active convective phase of the Madden–Julian oscillation (hereafter active MJO) comprises enhanced moist deep convection on its own temporal and spatial scales as well as increased variance in convection associated with higher-frequency ...
Paul E. Roundy
Results of Experiments on Convective Precipitation Enhancement in the Camaguey Experimental Area, Cuba
Experiments on randomized seeding of individual convective clouds and cloud clusters were conducted in the Camaguey experimental area, Cuba, from 1985 through 1990 in order to elucidate whether cold-cloud dynamic seeding can be used to augment ...
Boris Koloskov; Boris Zimin; Vitaly Beliaev; Yury Seregin; Albert Chernikov; Victor Petrov; Mario Valdés; Daniel Martínez; Carlos A. Pérez; Guillermo Puente
Does Mixing Promote Cloud Droplet Growth?
A systematic examination of cloud droplet size spectra from the Cooperative Convective Precipitation Experiment (CCOPE) reveals no tendency for an increase in the maximum droplet size with increasing dilution or cloud age.
Ilga R. Paluch; Charles A. Knight
Entrainment and Detrainment in Cumulus Clouds
Vertical redistribution of air and its properties inside convective clouds can be studied by standard thermodynamic analyses (Paluch and saturation point diagrams) if the clouds are nonprecipitating and ice free. It is shown from such analysis ...
Gregory R. Taylor; Marcia B. Baker
Thermodynamic and Circulation Characteristics, of Winter Monsoon Tropical Mesoscale Convection
During the December 1978 field phase of the International Winter Monsoon Experiment (Winter MONEX), a regular diurnal cycle of deep convective activity occurred over the South China Sea immediately to the north of Borneo. The convection was ...
Richad H. Johnson; Donald C. Kriete
Convective Contribution to the Genesis of Hurricane Ophelia (2005)
The convection occurring in the tropical depression that became Hurricane Ophelia (2005) was investigated just prior to tropical storm formation. Doppler radar showed a deep, wide, intense convective cell of a type that has been previously ...
Robert A. Houze Jr.; Wen-Chau Lee; Michael M. Bell
Hydrography of the Labrador Sea during Active Convection
The hydrographic structure of the Labrador Sea during wintertime convection is described. The cruise, part of the Deep Convection Experiment, took place in February–March 1997 amidst an extended period of strong forcing in an otherwise moderate ...
Robert S. Pickart; Daniel J. Torres; R. Allyn Clarke
Mesoscale Convective Complexes over Southern Africa
The maximum spatial correlation technique (MASCOTTE) is an objective and automated method developed to simultaneously determine both the structural properties and evolution (tracking) of cloud shields of convective systems. Originally designed to ...
R. C. Blamey; C. J. C. Reason
Measurement of Convective Entrainment Using Lagrangian Particles
Lagrangian particle tracking is used in a large-eddy simulation to study an individual cumulus congestus. This allows for the direct measurement of the convective entrainment rate and of the residence times of entrained parcels within the cloud. ...
Kyongmin Yeo; David M. Romps
Urban Aerosol Impacts on Downwind Convective Storms
The impacts of urban-enhanced aerosol concentrations on convective storm development and precipitation over and downwind of St. Louis, Missouri, are investigated. This is achieved through the use of a cloud-resolving mesoscale model, in which ...
Susan C. van den Heever; William R. Cotton
Association of Tropical Cirrus in the 10–15-km Layer with Deep Convective Sources: An Observational Study Combining Millimeter Radar Data and Satellite-Derived Trajectories
In this paper, millimeter cloud radar (MMCR) and Geosynchronous Meteorological Satellite (GMS) data are combined to study the properties of tropical cirrus that are common in the 10–15-km layer of the tropical troposphere in the western Pacific. ...
Gerald G. Mace; Min Deng; Brian Soden; Ed Zipser
The Impact of Airmass Boundaries on the Propagation of Deep Convection: A Modeling-Based Study in a High-CAPE, Low-Shear Environment
A suite of experiments conducted using a cloud-resolving model is examined to assess the role that preexisting airmass boundaries can play in regulating storm propagation. The 27 May 1997 central Texas tornadic event is used to guide these ...
Inclusion of Mesoscale Updrafts and Downdrafts in Computations of Vertical Fluxes by Ensembles of Tropical Clouds
Ensembles of convective clouds, especially in the tropics, often have widespread precipitating anvils associated with their deeper convective clouds. Mesoscale downdrafts occur below the middle-level bases of the anvils, and mesoscale updrafts ...
Robert A. Houze Jr.; Chee-Pong Cheng
Evolution of Eyewall Convective Events as Indicated by Intracloud and Cloud-to-Ground Lightning Activity during the Rapid Intensification of Hurricanes Rita and Katrina
Lightning data (cloud-to-ground plus intracloud) obtained from the Los Alamos Sferic Array (LASA) for 2005's Hurricanes Rita and Katrina were analyzed to provide a first insight into the three-dimensional electrical activity of rapidly ...
Alexandre O. Fierro; Xuan-Min Shao; Timothy Hamlin; Jon M. Reisner; Jeremiah Harlin
Nature versus Nurture in Shallow Convection
Tracers are used in a large-eddy simulation of shallow convection to show that stochastic entrainment (and not cloud-base properties) determines the fate of convecting parcels. The tracers are used to diagnose the correlations between a parcel's ...
David M. Romps; Zhiming Kuang
A New Parameterization for Shallow Cumulus Convection and Its Application to Marine Subtropical Cloud-Topped Boundary Layers. Part I: Description and 1D Results
A new parameterization of shallow cumulus convection is presented. The parameterization consists of a mass flux scheme based on a buoyancy-sorting, entrainment–detrainment plume model. The mass flux scheme is coupled to a 1.5-order turbulence ...
Christopher S. Bretherton; James R. McCaa; Hervé Grenier
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 ...
A Shallow CISK, Deep Equilibrium Mechanism for the Interaction between Large-Scale Convection and Large-Scale Circulations in the Tropics
In this paper, the circulations driven by deep heating and shallow heating are investigated through analytically solving a set of linear equations and examining circulations simulated by a dry primitive equation model. Special emphasis is placed ...
Zhaohua Wu
Evaluating Deep Updraft Formulation in NCAR CAM3 with High-Resolution WRF Simulations During ARM TWP-ICE
The updraft formulation used in NCAR CAM3 deep convection parameterization assumes that the fractional entrainment rate for a single updraft is height-independent and the updraft mass flux increases monotonically with height to updraft top. These assumptions are evaluated against three-dimensional high-resolution simulations from the weather research and forecast (WRF) model during the monsoon period of the DOE ARM Tropical Warm Pool -- International Cloud Experiment (TWP-ICE). Analyses of the WRF-generated updrafts suggest that the fractional entrainment rate for a single updraft decreases with height and the updraft mass flux increases with height below the top of the conditionally unstable layer but decreases above. It is suggested that the assumed updraft mass flux profile in CAM3 might be unrealistic in many cases because the updraft acceleration is affected by other drag processes in addition to entrainment. Total convective cloud mass flux and detrainment rate over the TWP-ICE domain diagnosed from the CAM3 parameterization driven by WRF meteorological fields are smaller than those derived from WRF simulations. The total entrainment rate of CAM3 is smaller than that of WRF in the lower part of cloud and larger in the upper part of cloud. Compared with WRF simulations, the CAM3-parameterized convection is too active and, as a result, excess moisture and heat may be transported to the upper troposphere by the parameterized convection. Future improvement is envisioned.
Wang, Weiguo; Liu, Xiaohong
Cloud-to-Ground Lightning Activity in the 10–11 June 1985 Mesoscale Convective System Observed during the Oklahoma–Kansas PRE-STORM Project
As part of the field program for the Oklahoma–Kansas PRE-STORM Project conducted in May–June 1985, a network of electromagnetic direction-finders was deployed to locate and detect the polarity of cloud-to-ground (CG) lighting flashes associated ...
Steven A. Rutledge; Donald R. MacGorman
Doppler Radar Sampling Limitations in Convective Storms
Vertical air motion data from a T-28 aircraft were filtered and sampled to simulate Doppler radar measurements. The results suggest that multiple Doppler radar analyses are subject to potentially large spatial aliasing errors in deep convection ...
R. E. Carbone; M. J. Carpenter; C. D. Burghart
Convective Squalls over the Eastern Equatorial Atlantic
The Congo Basin and the adjacent equatorial eastern Atlantic are among the most active regions of the world in terms of intense deep moist convection, leading to frequent lightning and severe squalls. Studying the dynamics and climatology of this ...
Florian Berkes; Peter Knippertz; Douglas J. Parker; Gus Jeans; Valérie Quiniou-Ramus
Evaluation of a Modified Scheme for Shallow Convection: Implementation of CuP and Case Studies
A new treatment for shallow clouds has been introduced into the Weather Research and Forecasting (WRF) model. The new scheme, called the cumulus potential (CuP) scheme, replaces the ad-hoc trigger function used in the Kain-Fritsch cumulus parameterization with a trigger function related to the distribution of temperature and humidity in the convective boundary layer via probability density functions (PDFs). An additional modification to the default version of WRF is the computation of a cumulus cloud fraction based on the time scales relevant for shallow cumuli. Results from three case studies over the U.S. Department of Energy's Atmospheric Radiation Measurement (ARM) site in north central Oklahoma are presented. These days were selected because of the presence of shallow cumuli over the ARM site. The modified version of WRF does a much better job predicting the cloud fraction and the downwelling shortwave irradiance thancontrol simulations utilizing the default Kain-Fritsch scheme. The modified scheme includes a number of additional free parameters, including the number and size of bins used to define the PDF, the minimum frequency of a bin within the PDF before that bin is considered for shallow clouds to form, and the critical cumulative frequency of bins required to trigger deep convection. A series of tests were undertaken to evaluate the sensitivity of the simulations to these parameters. Overall, the scheme was found to be relatively insensitive to each of the parameters.
Berg, Larry K.; Gustafson, William I.; Kassianov, Evgueni I.; Deng, Liping
Convection Initiation and Downburst Experiment (CINDE)
The Convection Initiation and Downburst Experiment (CINDE) was conducted in the Denver, Colorado area from 22 June to 7 August 1987 to study processes leading to the formation of deep convection and the physics of downbursts. A total of 6 Doppler ...
James W. Wilson; James A. Moore; G. Brant Foote; Brooks Martner; Taneil Uttal; James M. Wilczak; Alfred R. Rodi
An Intraseasonal Oscillation Composite Life Cycle in the NCAR CCM3.6 with Modified Convection
The NCAR CCM3.6 with microphysics of clouds with relaxed Arakawa–Schubert convection produces an intraseasonal oscillation that is highly dependent on lower-tropospheric moistening by surface convergence. Model intraseasonal convection is most ...
Eric D. Maloney
Observations of Convection Initiation "Failure" from the 12 June 2002 IHOP Deployment
Observations of the development of cumulus convection, which reached depths of several kilometers but failed to develop into sustained, precipitating, cumulonimbus clouds—an event the authors term "convection initiation failure"—are presented ...
Paul Markowski; Christina Hannon; Erik Rasmussen
Using the Stochastic Multicloud Model to Improve Tropical Convective Parameterization: A Paradigm Example
Despite recent advances in supercomputing, current general circulation models (GCMs) poorly represent the variability associated with organized tropical convection. A stochastic multicloud convective parameterization based on three cloud types (...
Yevgeniy Frenkel; Andrew J. Majda; Boualem Khouider
A Parameterization of the Cloudiness Associated with Cumulus Convection; Evaluation Using TOGA COARE Data
A new parameterization of the cloudiness associated with cumulus convection is proposed for use in climate models. It is based upon the idea that the convection scheme predicts the local concentration of condensed water (the in-cloud water ...
Sandrine Bony; Kerry A. Emanuel
A Numerical Case Study of Convection Initiation along Colliding Convergence Boundaries in Northeast Colorado
A numerical cloud model has been used to simulate convective storm development on 17 July 1987 in northeast Colorado. The study involves the simulation of convergence along atmospheric boundaries and the subsequent development of convection. The ...
Bruce D. Lee; Richard D. Farley; Mark R. Hjelmfelt
The Cooperative Convective Precipitation Experiment (CCOPE), 18 May-7 August 1981
The Cooperative Convective Precipitation Experiment, CCOPE, was an outgrowth of the perceived need for more comprehensive data sets on convective clouds. It was planned and executed by a large group of participants, with the leadership of the ...
Charles A. Knight
Simulations of stellar convection with CO5BOLD
High-resolution images of the solar surface show a granulation pattern of hot rising and cooler downward-sinking material - the top of the deep-reaching solar convection zone. Convection plays a role for the thermal structure of the solar interior and ... Keywords: Numerical simulations, Radiation (magneto)hydrodynamics, Stellar surface convection
B. Freytag; M. Steffen; H. -G. Ludwig; S. Wedemeyer-Böhm; W. Schaffenberger; O. Steiner
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
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.
Numerical Prediction of Convectively Driven Mesoscale Pressure Systems. Part I: Convective Parameterization
A parameterization formulation for incorporating the effects of midlatitude deep convection into mesoscale-numerical models is presented. The formulation is based on the hypothesis that the buoyant energy available to a parcel, in combination ...
J. M. Fritsch; C. F. Chappell
Variability of Graupel and Snow Observed in Tropical Oceanic Convection by Aircraft during TRMM KWAJEX
Empirical characterization of graupel and snow in precipitating tropical convective clouds is important for refining satellite precipitation retrieval algorithms and cloud-resolving and radiative transfer models. Microphysics data for this ...
Ellen M. Sukovich; David E. Kingsmill; Sandra E. Yuter
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
Aerosol Impacts on Clouds and Precipitation in Eastern China: Results from Bin and Bulk Microphysics
Using the Weather Research and Forecasting (WRF) model coupled with a 3 spectral-bin microphysics ('SBM') and measurements from the Atmospheric Radiation 4 Measurement (ARM) Mobile Facility field campaign in China (AMF-China), the authors 5 examine aerosol indirect effects (AIE) in the typical cloud regimes of the warm and cold 6 seasons in Southeast China: deep convective clouds (DCC) and stratus clouds (SC), 7 respectively. Comparisons with a two-moment bulk microphysics ('Bulk') are performed 8 to gain insights for improving bulk schemes in estimating AIE in weather and climate 9 simulations. For the first time, measurements of aerosol and cloud properties acquired in 10 China are used to evaluate model simulations to better understand AIE in China. It is 11 found that changes in cloud condensation nuclei (CCN) concentration significantly 12 change the timing of storms, the spatial and temporal distributions of precipitation, the 13 frequency distribution of precipitation rate, as well as cloud base and top heights for the 14 DCC, but not for the SC. CCN increase cloud droplet number (Nc) and mass 15 concentrations, decrease raindrop number concentration (Nr), and delay the onset of 16 precipitation. It is indicated much higher Nc and the opposite CCN effects on convection 17 and heavy rain with Bulk compared to SBM stem from the fixed CCN prescribed in Bulk. 18 CCN have a significant effect on ice microphysical properties with SBM but not Bulk 19 and different condensation/deposition freezing parameterizations employed could be the 20 main reason. This study provided insights to further improve the bulk scheme to better 21 account for aerosol-cloud interactions in regional and global climate simulations, which 22 will be the focus for a follow-on paper.
Fan, Jiwen; Leung, Lai-Yung R.; Li, Zhanqing; Morrison, H.; Chen, Hongbin; Zhou, Yuquan; Qian, Yun; Wang, Yuan
Cloud Optical Thickness Estimation from Irradiance Measurements
Radiative transfer algorithms are developed to estimate the optical thickness of clouds using an irradiance detector located above, deep within, and beneath a cloud. Both monodirectional and diffuse illumination cases are considered. For each ...
H. C. Yi; N. J. McCormick; R. Sanchez
Global ice cloud observations: radiative properties and statistics from moderate-resolution imaging spectroradiometer measurements
Ice clouds occur quite frequently, yet so much about these clouds is unknown. In recent years, numerous investigations and field campaigns have been focused on the study of ice clouds, all with the ultimate goal of gaining a better understanding of microphysical and optical properties, as well as determining the radiative impact. Perhaps one of the most recognized instruments used for such research is the Moderate-resolution Imaging Spectroradiometer (MODIS), carried aboard the NASA EOS satellites Terra and Aqua. The present research aims to support ongoing efforts in the field of ice cloud research by use of observations obtained from Terra and Aqua MODIS. First, a technique is developed to infer ice cloud optical depth from the MODIS cirrus reflectance parameter. This technique is based on a previous method developed by Meyer et al. (2004). The applicability of the algorithm is demonstrated with retrievals from level-2 and -3 MODIS data. The technique is also evaluated with the operational MODIS cloud retrieval product and a method based on airborne ice cloud observations. From this technique, an archive of daily optical depth retrievals is constructed. Using simple statistics, the global spatial and temporal distributions of ice clouds are determined. Research has found that Aqua MODIS observes more frequent ice clouds and larger optical depths and ice water paths than does Terra MODIS. Finally, an analysis of the time series of daily optical depth values revealed that ice clouds at high latitudes, which are most likely associated with synoptic scale weather sytems, persist long enough to move with the upper level winds. Tropical ice clouds, however, dissipate more rapidly, and are in all likelihood associated with deep convective cells.
Meyer, Kerry Glynne
A Model of Rossby Waves Linked to Submonthly Convection over the Eastern Tropical Pacific
Equatorward-propagating wave trains in the upper troposphere are observed to be associated with deep convection over the eastern tropical Pacific on the submonthly timescale during northern winter. The convection occurs in the regions of ascent ...
Adrian J. Matthews; George N. Kiladis
Improved Madden–Julian Oscillations with Improved Physics: The Impact of Modified Convection Parameterizations
Two modifications are made to the deep convection parameterization in the NCAR Community Climate System Model, version 3 (CCSM3): a dilute plume approximation and an implementation of the convective momentum transport (CMT). These changes lead to ...
Lei Zhou; Richard B. Neale; Markus Jochum; Raghu Murtugudde
Atmospheric Circulation Anomalies during Episodes of Enhanced and Reduced Convective Cloudiness over Uruguay
Regional and large-scale circulation anomalies associated with periods of enhanced and reduced convective cloudiness over Uruguay are studied for austral spring and summer, when rainfall associated with deep convection is more frequent in this ...
Alvaro DÍaz; Patricio Aceituno
The Role of Gravity Waves in the Formation and Organization of Clouds during TWPICE
All convective clouds emit gravity waves. While it is certain that convectively-generated waves play important parts in determining the climate, their precise roles remain uncertain and their effects are not (generally) represented in climate models. The work described here focuses mostly on observations and modeling of convectively-generated gravity waves, using the intensive observations from the DoE-sponsored Tropical Warm Pool International Cloud Experiment (TWP-ICE), which took place in Darwin, from 17 January to 13 February 2006. Among other things, the research has implications the part played by convectively-generated gravity waves in the formation of cirrus, in the initiation and organization of further convection, and in the subgrid-scale momentum transport and associated large-scale stresses imposed on the troposphere and stratosphere. The analysis shows two groups of inertia-gravity waves are detected: group L in the middle stratosphere during the suppressed monsoon period, and group S in the lower stratosphere during the monsoon break period. Waves belonging to group L propagate to the south-east with a mean intrinsic period of 35 h, and have vertical and horizontal wavelengths of about 5-6 km and 3000-6000 km, respectively. Ray tracing calculations indicate that these waves originate from a deep convective region near Indonesia. Waves belonging to group S propagate to the south-south-east with an intrinsic period, vertical wavelength and horizontal wavelength of about 45 h, 2 km and 2000-4000 km, respectively. These waves are shown to be associated with shallow convection in the oceanic area within about 1000 km of Darwin. The intrinsic periods of high-frequency waves are estimated to be between 20-40 minutes. The high-frequency wave activity in the stratosphere, defined by mass-weighted variance of the vertical motion of the sonde, has a maximum following the afternoon local convection indicating that these waves are generated by local convection. The wave activity is strongest in the lower stratosphere below 22 km and, during the suppressed monsoon period, is modulated with a 3-4-day period. The concentration of the wave activity in the lower stratosphere is consistent with the properties of the environment in which these waves propagate, whereas its 3-4-day modulation is explained by the variation of the convection activity in the TWP-ICE domain. At low rainfall intensity the wave activity increases as rainfall intensity increases. At high values of rainfall intensity, however, the wave activity associated with deep convective clouds is independent of the rainfall intensity. The convection and gravity waves observed during TWP-ICE are simulated with the Weather Research and Forecasting (WRF) Model. These simulations are compared with radiosonde observations described above and are used to determine some of the properties of convectively generated gravity waves. The gravity waves appear to be well simulated by the model. The model is used to explore the relationships between the convection, the gravity waves and cirrus.
Reeder, Michael J. [Monash University; Lane, Todd P. [University of Melbourne; Hankinson, Mai Chi Nguyen [Monash University
Physical Characterization of Tropical Oceanic Convection Observed in KWAJEX
The Tropical Rainfall Measuring Mission (TRMM) Kwajalein Experiment (KWAJEX) was designed to obtain an empirical physical characterization of precipitating convective clouds over the tropical ocean. Coordinated datasets were collected by three ...
Sandra E. Yuter; Robert A. Houze Jr.; Eric A. Smith; Thomas T. Wilheit; Edward Zipser
Fluctuations in an Equilibrium Convective Ensemble. Part I: Theoretical Formulation
To provide a theoretical basis for stochastic parameterization of cumulus convection, the equilibrium fluctuations of a field of cumulus clouds under homogeneous large-scale forcing are derived statistically, using the Gibbs canonical ensemble ...
George C. Craig; Brenda G. Cohen
Convective Boundary Layers Driven by Nonstationary Surface Heat Fluxes
In this study the response of dry convective boundary layers to nonstationary surface heat fluxes is systematically investigated. This is relevant not only during sunset and sunrise but also, for example, when clouds modulate incoming solar ...
Robert van Driel; Harm J. J. Jonker
On the Generation of Convectively Driven Mesohighs Aloft
In an attempt to determine the relative contribution of the direct incorporation of cold air (detrainment from overshooting convective cloud tops) to the production of mesohighs in the vicinity of the tropopause, two numerical simulations were ...
J. M. Fritsch; J. M. Brown
Synoptic Mapping of Convective Structure from Undersampled Satellite Observations
Climate properties regulated by convection, such as water vapor, cloud cover, and related distributions, are undersampled in asynoptic data from an individual orbiting platform, which must therefore be restricted to time-mean distributions. A ...
Murry Salby; Fabrizio Sassi
Transient Environmental Sensitivities of Explicitly Simulated Tropical Convection
A three-dimensional cloud-resolving model, maintained in a statistically steady convecting state by tropics-like forcing, is subjected to sudden (10 min) stimuli consisting of horizontally homogeneous temperature and/or moisture sources with ...
Two-Zone Convective Scaling of Diffusion in Complex Terrain
A "two-zone" convective scaling equation is developed that allows for a step change in scaling parameters. The results of the Lompoc Valley Diffusion Experiment, conducted at coastal site in California under variable cloud cover, are compared to ...
C. E. Skupniewicz
Evaluation of Parametric Assumptions for Shallow Cumulus Convection
A large-eddy simulation (LES) model has been utilized to study nonprecipitating Shallow Convective clouds such as observed during the undisturbed BOMEX period in the trade wind areas. By choosing a realistic large-scale forcing the authors have ...
A. P. Siebesma; J. W. M. Cuijpers
Equatorial Wave Activity Derived from Fluctuations in Observed Convection
The spectrum of equatorial wave activity propagating vertically into the stratosphere is calculated from high-resolution imagery of the global convective pattern. Synoptic Global Cloud Imagery (GCI), constructed from six satellites simultaneously ...
John W. Bergman; Murry L. Salby
The Influence of Helicity on Numerically Simulated Convective Storms
A three-dimensional numerical cloud model is used to investigate the influence of storm-relative environmental helicity (SREH) on convective storm structure and evolution, with a particular emphasis on the identification of ambient shear profiles ...
Kelvin K. Droegemeier; Steven M. Lazarus; Robert Davies-Jones
Airborne Doppler Lidar Observations of Convective Phenomena in Oklahoma
On 30 June 1981, the wind fields around a variety of convective clouds, ranging from large thunderstorm complexes to isolated cumulus congestus, were observed in Oklahoma using an airborne Doppler lidar operated by the National Aeronautics and ...
Eugene W. McCaul Jr.; Howard B. Bluestein; Richard J. Doviak
Comparing Model-produced Convective Cloudiness with Observations
Convective cloudiness generated by a cumulus parameterization scheme of a large-scale numerical weather prediction model was compared with analyses of clouds observed by geosynchronous satellites. The comparisons were performed over an equatorial ...
D. C. Norquist; C. Yang
An Enhanced Geostationary Satellite–Based Convective Initiation Algorithm for 0–2-h Nowcasting with Object Tracking
This paper describes an enhanced 0–2-h convective initiation (CI) nowcasting algorithm known as Satellite Convection Analysis and Tracking, version 2 (SATCASTv2). Tracking of developing cumulus cloud "objects" in advance of CI was developed as a ...
John R. Walker; Wayne M. MacKenzie Jr.; John R. Mecikalski; Christopher P. Jewett
Numerical Simulation of the Interaction between the Sea-Breeze Front and Horizontal Convective Rolls. Part I: Offshore Ambient Flow
A three-dimensional, cloud-resolving model is used to investigate the interaction between the sea-breeze circulation and boundary layer roll convection. Horizontal convective rolls (HCRs) develop over land in response to strong daytime surface ...
Peter S. Dailey; Robert G. Fovell
Validation of Satellite-Based Objective Overshooting Cloud-Top Detection Methods Using CloudSat Cloud Profiling Radar Observations
Two satellite infrared-based overshooting convective cloud-top (OT) detection methods have recently been described in the literature: 1) the 11-?m infrared window channel texture (IRW texture) method, which uses IRW channel brightness temperature (...
Kristopher M. Bedka; Richard Dworak; Jason Brunner; Wayne Feltz
Convection towers
DOE Patents (OSTI)
Convection towers which are capable of cleaning the pollution from large quantities of air, of generating electricity, and of producing fresh water utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity, and condensers produce fresh water. 6 figs.
Prueitt, M.L.
Convection towers which are capable of cleaning the pollution from large quantities of air, of generating electricity, and of producing fresh water utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity, and condensers produce fresh water.
Prueitt, Melvin L. (Los Alamos, NM)
Convection towers which are capable of cleaning the pollution from large quantities of air and of generating electricity utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity. Other embodiments may also provide fresh water, and operate in an updraft mode.
Cloud Geometry Effects on Atmospheric Solar Absorption
A 3D broadband solar radiative transfer scheme is formulated by integrating a Monte Carlo photon transport algorithm with the Fu–Liou radiation model. It is applied to fields of tropical mesoscale convective clouds and subtropical marine boundary ...
Qiang Fu; M. C. Cribb; H. W. Barker; S. K. Krueger; A. Grossman
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
Convection towers which are capable of cleaning the pollution from large quantities of air and of generating electricity utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity. Other embodiments may also provide fresh water, and operate in an updraft mode. 5 figures.
Fluctuation of Mass Flux in a Cloud-Resolving Simulation with Interactive Radiation
It was shown by Craig and Cohen that fluctuations of cumulus clouds under homogeneous large-scale forcing satisfy the Gibbs canonical ensemble in a strict radiative–convective equilibrium (RCE). In the limit of random noninteracting convective ...
J. Davoudi; N. A. McFarlane; T. Birner
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
Indirect Impact of Atmospheric Aerosols in Idealized Simulations of Convective–Radiative Quasi Equilibrium. Part II: Double-Moment Microphysics
This paper extends the previous cloud-resolving modeling study concerning the impact of cloud microphysics on convective–radiative quasi equilibrium (CRQE) over a surface with fixed characteristics and prescribed solar input, both mimicking the ...
Wojciech W. Grabowski; Hugh Morrison
An homogeneous nuclear power reactor utilizing convection circulation of the liquid fuel is proposed. The reactor has an internal heat exchanger looated in the same pressure vessel as the critical assembly, thereby eliminating necessity for handling the hot liquid fuel outside the reactor pressure vessel during normal operation. The liquid fuel used in this reactor eliminates the necessity for extensive radiolytic gas rocombination apparatus, and the reactor is resiliently pressurized and, without any movable mechanical apparatus, automatically regulates itself to the condition of criticality during moderate variations in temperature snd pressure and shuts itself down as the pressure exceeds a predetermined safe operating value.
Hammond, R.P.; King, L.D.P.
Structure of Large-Scale Convective Anomalies over Tropical Oceans
Geographical variations in the variance and cross-correlation of monthly mean sea surface temperature (SST), outgoing longwave radiation (OLR, a proxy for deep convection and vertical motion), and convergence of winds at the surface and at 850 mb ...
David S. Gutzler; Tamara M. Wood
Wintertime Convection in a Gulf stream Warm Core Ring
Wintertime convection creates deep mixed layers which determine the water mass characteristics and potential vorticity for waters in the main pycnocline of the world ocean. Diabatic cooling is most intense in the Northern Hemisphere near the ...
Terrence M. Joyce; Marvel C. Stalcup
Extreme Helicity and Intense Convective Towers in Hurricane Bonnie
Helicity was calculated in Hurricane Bonnie (1998) using tropospheric-deep dropsonde soundings from the NASA Convection and Moisture Experiment. Large helicity existed downshear of the storm center with respect to the ambient vertical wind shear. ...
John Molinari; David Vollaro
Sampling Characteristics from Isobaric Floats in a Convective Eddy Field
During the recent Labrador Sea Deep Convection Experiment, numerous isobaric floats were deployed. Interpretation of the quasi-Lagrangian measurements from these floats requires an understanding of any biases that may be introduced by the ...
Sonya Legg; James C. McWilliams
A Study of Convection Initiation in a Mesoscale Model Using High-Resolution Land Surface Initial Conditions
A coupled convection-resolving mesoscale atmosphere–land surface model (LSM) is used to investigate land surface–planetary boundary layer (PBL) interactions responsible for the initiation of deep, moist convection over the southern Great Plains ...
Stanley B. Trier; Fei Chen; Kevin W. Manning
Variations in the Flow of the Global Atmosphere Associated with a Composite Convectively Coupled Oceanic Kelvin Wave
Kelvin waves in the Pacific Ocean occasionally develop and propagate eastward together with anomalies of deep convection and low-level westerly wind. This pattern suggests coupling between the oceanic waves and atmospheric convection. A simple ...
Paul E. Roundy; Lynn M. Gribble-Verhagen
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 Magnitude of the Electric Field near Thunderstorm-Associated Clouds
Electric-field measurements made in and near clouds during two airborne field programs are presented. Aircraft equipped with multiple electric-field mills and cloud physics sensors were flown near active convection and into thunderstorm anvil and ...
Francis J. Merceret; Jennifer G. Ward; Douglas M. Mach; Monte G. Bateman; James E. Dye
Visual Cloud Histories Related to First Radar Echo Formation in Northeast Colorado Cumulus
Using quantitative analysis of time-lapse motion pictures from aircraft and a sensitive meteorological radar, the cloud top history is related to the early radar echo development in 12 vigorous, summer, convective cloud turrets in northeastern ...
Charles A. Knight; William D. Hall; Philip M. Roskowski
An Intercomparison of UW Cloud-Top Cooling Rates with WSR-88D Radar Data
The University of Wisconsin Convective Initiation (UWCI) algorithm utilizes geostationary IR satellite data to compute cloud-top cooling (UW-CTC) rates and assign CI nowcasts to vertically growing clouds. This study is motivated by National ...
Daniel C. Hartung; Justin M. Sieglaff; Lee M. Cronce; Wayne F. Feltz
Structure and Evolution of North Australian Cloud Lines Observed during AMEX Phase I
North Australian Clouds Lines are distinctive, squall-line phenomena that occur in easterly flow across northern Australia. Three basic types have been identified, ranging from a long, narrow line of convective clouds (Type 1) to a severe squall ...
Wasyl Drosdowsky; Greg J. Holland; Roger K. Smith
Analysis of Convective Activity and Its Relationship to the Rainfall over the Rift Valley Lakes of East Africa during 1983–90 Using the Meteosat Infrared Channel
The convective activity over the Rift Valley lakes of East Africa, as deduced from cloud tops colder than a predefined threshold, is examined. Relationships between satellite-derived convective indices and rainfall measurements are also examined. ...
Mamoudou B. Ba; Sharon E. Nicholson
Convective Cloud Climatologies Constructed from Satellite Imagery
Composites of satellite imagery are constructed for various hours and various summer months on Colorado State University's interactive processing system. Simple averages of visible wavelength imagery are considered as well as averages of ...
Marjorie A. Klitch; John F. Weaver; Frank P. Kelly; Thomas H. Vonder Haar
Convective heater
A convective heater for heating fluids such as a coal slurry is constructed of a tube circuit arrangement which obtains an optimum temperature distribution to give a relatively constant slurry film temperature. The heater is constructed to divide the heating gas flow into two equal paths and the tube circuit for the slurry is arranged to provide a mixed flow configuration whereby the slurry passes through the two heating gas paths in successive co-current, counter-current and co-current flow relative to the heating gas flow. This arrangement permits the utilization of minimum surface area for a given maximum film temperature of the slurry consistent with the prevention of coke formation. 14 figs.
Thorogood, R.M.
A convective heater for heating fluids such as a coal slurry is constructed of a tube circuit arrangement which obtains an optimum temperature distribution to give a relatively constant slurry film temperature. The heater is constructed to divide the heating gas flow into two equal paths and the tube circuit for the slurry is arranged to provide a mixed flow configuration whereby the slurry passes through the two heating gas paths in successive co-current, counter-current and co-current flow relative to the heating gas flow. This arrangement permits the utilization of minimum surface area for a given maximum film temperature of the slurry consistent with the prevention of coke formation.
Thorogood, Robert M. (Macungie, PA)
Interannual Variability of Deep-Water Formation in the Northwestern Mediterranean
In the Gulf of Lions, observations of deep convection have been sporadically carried out over the past three decades, showing significant interannual variability of convection activity. As long time series of meteorological observations of the ...
C. Mertens; F. Schott
Convective Building of a Pycnocline: Laboratory Experiments
The convective building of a pycnocline is examined using a laboratory model forced by surface fluxes of saline water at one end and fresh water at the other. A deep recirculation evolves in the tank, which homogenizes the interior fluid by ...
David W. Pierce; Peter B. Rhines
Radiative-Convective Equilibrium with Explicit Two-Dimensional Moist Convection
Radiative-convective statistical equilibria are obtained using a two-dimensional model in which radiative transfer is interactive with the predicted moisture and cloud fields. The domain is periodic in x, with a width of 640 km, and extends from ...
Isaac M. Held; Richard S. Hemler; V. Ramaswamy
Retrieval of Cloud Water and Water Vapor Contents from Doppler Radar Data in a Tropical Squall Line
This paper describes the retrieval of cloud water and water vapor contents from Doppler radar data. The convective part of a tropical squall line (22 June 1981) observed during the COPT 81 (Convection Profonde Tropicale 1981) West African ...
Daničle Hauser; Paul Amayenc
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.
Properties of tropical convection observed by ARM millimeter-radars
Properties of tropical convection observed by ARM millimeter-radars Properties of tropical convection observed by ARM millimeter-radars Haynes, John Colorado State University Stephens, Graeme Colorado State University Category: Cloud Properties The results of an analysis of tropical cloud systems observed from a variety of vertically pointing radar systems are described. In particular, observations taken during five years of operation of the ARM millimeter wavelength radar system (MMCR) at Manus Island in the Tropical West Pacific region are characterized into cloud classes according to the radar reflectivity structures of these cloud systems, associated rainfall, and surface radiative properties. These observations of cloud properties are composited with respect to various phases of the Madden Julian Oscillation, which is a dominant mode of variability at Manus Island. A method of better
Diurnal Cycle of Convection at the ARM SGP Site: Role of Large-Scale Forcing, Surface Fluxes, and Convective Inhibition
Diurnal Cycle of Convection at the ARM SGP Site: Diurnal Cycle of Convection at the ARM SGP Site: Role of Large-Scale Forcing, Surface Fluxes, and Convective Inhibition G. J. Zhang Center for Atmospheric Sciences Scripps Institution of Oceanography La Jolla, California Introduction Atmospheric convection undergoes strong diurnal variation over both land and oceans (Gray and Jacobson 1977; Dai 2001; Nesbitt and Zipser 2003). Because of the nature of the diurnal variation of solar radiation, the phasing of convection with solar radiation has a significant impact on the atmospheric radiation budget and cloud radiative forcing. A number of studies have investigated the possible mechanisms of the diurnal variation of convection (Gray and Jacobson 1977; Randall et al. 1991; Dai et al. 1999; Dai 2001). Yet, in regional and global climate models, the diurnal variation of
Mesoscale and Microscale Structure of Cirrus Clouds: Three Case Studies
The structure and composition of three basic cirrus cloud types are examined through coordinated aircraft and ground-based polarization lidar and radar measurements. The cloud systems consist of a multilayered orographic cirrus, a 6-km deep ...
Kenneth Sassen; David O'C. Starr; Taneil Uttal
Observations of Cloud Microstructure at the Centimeter Scale
Current conceptual models of the processes that modify the droplet spectrum in convective clouds starts with entrainment of environmental air followed by turbulent mixing of these parcels into progressively finer filaments. Thus, one would expect,...
Jean-Louis Brenguier
Tracer Study of Vertical Exchange by Cumulus Clouds
This paper examines the exchange of material by convective cloud processes between the mixed layer and the overlying free troposphere. It describes results of a field experiment that was conducted in Lexington, Kentucky, during the period from 20 ...
J. K. S. Ching; A. J. Alkezweeny
SST Sensitivities in Multiday TOGA COARE Cloud-Resolving Simulations
A two-dimensional cloud-resolving model (CRM) was used to simulate the evolution of convection over the western Pacific between 19 and 26 December 1992, during the Tropical Ocean Global Atmosphere Coupled Ocean–Atmosphere Response Experiment. A ...
Alexandre A. Costa; William R. Cotton; Robert L. Walko; Roger A. Pielke Sr.; Hongli Jiang
The Relationship of Highly Reflective Clouds to Tropical Climate Anomalies
The interannual variability of tropical convection related to the Southern Oscillation (SO) and regional climate anomalies is studied from satellite-derived estimates of highly reflective clouds (HRC) during 1971–87. The novel HRC data bank ...
Stefan Hastenrath
Small-Scale Variability in Warm Continental Cumulus Clouds
We have analyzed small-scale fluctuations in microphysical, dynamical and thermodynamical parameters measured in two warm cumulus clouds during the Cooperative Convective Precipitation Experiment (CCOPE) project (1981) in light of predictions of ...
P. H. Austin; M. B. Baker; A. M. Blyth; J. B. Jensen
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
A Cloud-Resolving Simulation Study on the Merging Processes and Effects of Topography and Environmental Winds
The cloud-resolving fifth-generation Pennsylvania State University–National Center for Atmospheric Research Mesoscale Model (MM5) was used to study the cloud interactions and merging processes in the real case that generated a mesoscale convective ...
Danhong Fu; Xueliang Guo
Severe Convective Wind Environments
Nontornadic thunderstorm winds from long-lived, widespread convective windstorms can have a tremendous impact on human lives and property. To examine environments that support damaging wind producing convection, sounding parameters from Rapid ...
Evan L. Kuchera; Matthew D. Parker
An Analysis of Convective System on a 100-km Scale during GATE
Usig data on a 100 km-scale from Phase III of GATE, the kinematic and thermodynamic, properties of the mesoscale environment in which convective clouds of varying intensities exist are investigated. Classifications into disturbed and suppressed ...
R. P. Pearce; J. Bayo Omotosho
The Dependence of Numerically Simulated Convective Storms on Vertical Wind Shear and Buoyancy
The effects of vertical wind shear and buoyancy on convective storm structure and evolution are investigated with the use of a three-dimensional numerical cloud model. By varying the magnitude of buoyant energy and one-directional vertical shear ...
M. L. Weisman; J. B. Klemp
Sensitivity of Tropical Convection to Sea Surface Temperature in the Absence of Large-Scale Flow
The response of convection to changing sea surface temperature (SST) in the absence of large-scale flow is examined, using a three-dimensional cloud resolving model. The model includes a five-category bulk microphysical scheme representing snow, ...
Adrian M. Tompkins; George C. Craig
Effects of Tropospheric Wind Shear on the Spectrum of Convectively Generated Gravity Waves
The authors examine the effects of tropospheric wind shear on the phase speed spectrum of gravity waves generated by tropical convection. A two-dimensional cloud-resolving model is used to perform numerous squall line simulations with the ...
Jadwiga H. Beres; M. Joan Alexander; James R. Holton
Improving Convective Precipitation Forecasting through Assimilation of Regional Lightning Measurements in a Mesoscale Model
A technique developed for assimilating regional lightning measurements into a meteorological model is presented in this paper. The goal is to assess the effectiveness of cloud-to-ground (CG) lightning information for improving the convective ...
Anastasios Papadopoulos; Themis G. Chronis; Emmanouil N. Anagnostou
Thermally Induced Compression Waves and Gravity Waves Generated by Convective Storms
A three-dimensional, fully compressible cloud model is used to simulate a convective storm in order to investigate the properties of compression waves and gravity waves induced by latent heat release. Time series of the low-level pressure ...
Melville E. Nicholls; Roger A. Pielke Sr.
A Numerical Simulation Study of the Effects of Anvil Shading on Quasi-Linear Convective Systems
Numerical simulations are used to investigate how the attenuation of solar radiation by the intervening cumulonimbus cloud, particularly its large anvil, affects the structure, intensity, and evolution of quasi-linear convective systems and the ...
Andrew J. Oberthaler; Paul M. Markowski
Collective Effects of Organized Convection and Their Approximation in General Circulation Models
The collective effects of organized convection the environment were estimated using a two-dimensional, two-way nested cloud-resolving numerical model with a large outer domain (4500 km). As initial conditions, the authors used an idealized ...
Xiaoqing Wu; Mitchell W. Moncrieff
A One-Dimensional Entraining/Detraining Plume Model and Its Application in Convective Parameterization
A new one-dimensional cloud model, specifically designed for application in mesoscale convective parameterization schemes (CPSs), is introduced. The model is unique in its representation of environmental entrainment and updraft detrainment rates. ...
John S. Kain; J. Michael Fritsch
Convective Rain Rates and their Evolution during Storms in a Semiarid Climate
Rain rates and their evolution during summertime convective storms were analyzed for the semiarid climate of the northern High Plains. Radar data from a total of 750 radar echo clusters from the 1980 and 1981 summer cloud seeding operations of ...
AndréA. Doneaud; Stefano Ionescu-Niscov; James R. Miller Jr.
Large Eddy Simulation of Turbulent Flow in a Marine Convective Boundary Layer with Snow
A large eddy simulation (LES) model, with ice phase included, has been used to study the marine convective boundary layer filled with snow. Extensions to Moeng's LES model include the diagnosis of cloud ice mixing ratio, snow precipitation, and ...
Guan-Shu Rao; Ernest M. Agee
Automatic Tracking and Characterization of African Convective Systems on Meteosat Pictures
With the objective of budding climatological statistics on propagating African convective systems and extracting pertinent parameters for the evaluation of precipitation an automatic method of tracking clouds with cold tops on Meteosat infrared (...
Yves Arnaud; Michel Desbois; Joel Maizi
Global Variability of Mesoscale Convective System Anvil Structure from A-Train Satellite Data
Mesoscale convective systems (MCSs) in the tropics produce extensive anvil clouds, which significantly affect the transfer of radiation. This study develops an objective method to identify MCSs and their anvils by combining data from three A-...
Scalar Turbulence in Convective Boundary Layers by Changing the Entrainment Flux
A large-eddy simulation model is adopted to investigate the evolution of scalars transported by atmospheric cloud-free convective boundary layer flows. Temperature fluctuations due to the ground release of sensible heat and concentration ...
Alessandra S. Lanotte; Irene M. Mazzitelli
Distribution and Statistics of African Mesoscale Convective Weather Systems Based on the ISCCP Meteosat Imagery
This paper provides for the first time an objective short-term (8 yr) climatology of African convective weather systems based on satellite imagery. Eight years of infrared International Satellite Cloud Climatology Project–European Space Agency's ...
K. I. Hodges; C. D. Thorncroft
Episodic Mixing and Buoyancy-Sorting Representations of Shallow Convection: A Diagnostic Study
Episodic mixing and buoyancy-sorting (EMBS) models have been proposed as a physically more realistic alternative to entraining plume models of cumulus convection. Applying these models to shallow nonprecipitating clouds requires assumptions about ...
Ming Zhao; Philip H. Austin
Some Observational Evidence for Dry Soils Supporting Enhanced Relative Humidity at the Convective Boundary Layer Top
The tendency of the relative humidity at the top of a clear convective boundary layer (RHtop) is studied as an indicator of cloud formation over a semiarid region within the conceptual framework introduced by Ek and Holtslag. Typically the ...
D. Westra; G. J. Steeneveld; A. A. M. Holtslag
Potential Vorticity Accumulation Following Atmospheric Kelvin Waves in the Active Convective Region of the MJO
Previous works have shown that most of the rainfall embedded within the Madden–Julian oscillation (MJO) occurs in large eastward-moving envelopes of enhanced convection known as super cloud clusters. Many of these superclusters have been ...
Kyle MacRitchie; Paul E. Roundy
Surface and atmospheric controls on the onset of moist convection over land
The onset of moist convection over land is investigated using a conceptual approach with a slab boundary layer model. We here determine the essential factors for the onset of boundary layer clouds over land, and study their relative importance. ...
Pierre Gentine; Albert A. M. Holtslag; Fabio D'Andrea; Michael Ek
Convective Tendency Images Derived from a Combination of Lightning and Satellite Data
A technique is presented for generating convective tendency products by combining satellite images with observations of cloud-to-ground lightning activity. Rapid scan (5-min) infrared satellite images are used to define the areal distribution of ...
Steven J. Goodman; Dennis E. Buechler; Paul J. Meyer
A Modeling Study on the Early Electrical Development of Tropical Convection: Continental and Oceanic (Monsoon) Storms
Numerical modeling studies of continental tropical and maritime tropical convection were conducted using the two-dimensional, nonhydrostatic, cloud electrification model developed at the South Dakota School of Mines and Technology. The model ...
Scot C. Randell; Steven A. Rutledge; Richard D. Farley; John H. Helsdon Jr.
On the Linkage between Antarctic Surface Water Stratification and Global Deep-Water Temperature
The suggestion is advanced that the remarkably low static stability of Antarctic surface waters may arise from a feedback loop involving global deep-water temperatures. If deep-water temperatures are too warm, this promotes Antarctic convection, ...
Ralph F. Keeling; Martin Visbeck
Improving Convection Parameterization Using ARM Observations and NCAR Community Atmosphere Model
Highlight of Accomplishments: We made significant contribution to the ASR program in this funding cycle by better representing convective processes in GCMs based on knowledge gained from analysis of ARM/ASR observations. In addition, our work led to a much improved understanding of the interaction among aerosol, convection, clouds and climate in GCMs.
Zhang, Guang J [Scripps Institution of Oceanography
The ARAUCARIA project: Deep near-infrared survey of nearby galaxies. I. The distance to the Large Magellanic Cloud from K-band photometry of red clump stars
We have obtained deep imaging in the near-infrared J and K bands for 2 nearby fields in the bar of the LMC with the ESO NTT telescope, under exquisite seeing conditions. The K, J-K color-magnitude diagrams constructed from these data are of outstanding photometric quality and reveal the presence of several hundreds of red clump stars. Using the calibration of Alves for the K-band absolute magnitude of Hipparcos-observed red clump stars in the solar neigbourhood we derive a distance modulus to our observed LMC fields of 18.487 mag. Applying a correction for the tilt of the LMC bar with respect to the line of sight according to the geometrical model of van der Marel et al., the corresponding LMC barycenter distance is 18.501 mag. If we adopt a K-band population correction of -0.03 mag, as done by Alves et al. 2002, to account for the difference in age and metallicity between the solar neighborhood and LMC red clump star populations, we obtain an LMC barycenter distance modulus of 18.471 mag from our data. This is in excellent agreement with the result of Alves et al., and of another very recent study of Sarajedini et al. (2002) obtained from K-band photometry. However, we emphasize that current model predictions about the uncertainties of population corrections seem to indicate that errors up to about 0.12 mag may be possible, probably in any photometric band. Therefore, work must continue to tighten the constraints on these corrections. We also determine the mean red clump star magnitude in our LMC fields in the J band, which could be a useful alternative to the K band should future work reveal that population effect corrections for red clump stars in the J band are smaller, or more reliably determined than those for the K band.
G. Pietrzynski; W. Gieren
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
Leading and Trailing Anvil Clouds of West African Squall Lines
The anvil clouds of tropical squall-line systems over West Africa have been examined using cloud radar data and divided into those that appear ahead of the leading convective line and those on the trailing side of the system. The leading anvils ...
Jasmine Cetrone; Robert A. Houze Jr.
Effects of Cloud Seeding, Latent Heat of Fusion, and Condensate Loading on Cloud Dynamics and Precipitation Evolution: A Numerical Study
This study attempts to isolate the dynamic and microphysical effects of seeding. A two-dimensional, time-dependent cloud model has been used to simulate silver iodide (AgI) seeding of convective clouds. Two major dynamic effects (latent heat of ...
Harold D. Orville; Jeng-Ming Chen
TWP-ICE Global Atmospheric Model Intercomparison: Convection Responsiveness and Resolution Impact
Results are presented from an intercomparison of global atmospheric model (GAM) simulations of tropical convection during the Tropical Warm Pool-International Cloud Experiment (TWP-ICE). The distinct cloud properties, precipitation, radiation, and vertical diabatic heating profiles associated with three different monsoon regimes (wet, dry, and break) from available observations are used to evaluate 9 GAM forecasts initialized daily from realistic global analyses. All models well captured the evolution of large-scale circulation and the thermodynamic fields, but cloud properties differed substantially among models. For example, liquid water path and ice water path differed by up to two orders of magnitude. Compared with the relatively well simulated top-heavy heating structures during the wet and break period, most models had difficulty in depicting the bottom-heavy heating profiles associated with cumulus congestus. The best performing models during this period were the ones whose convection scheme was most responsive to the free tropospheric humidity. Compared with the large impact of cloud and convective parameterizations on model cloud and precipitation characteristics, resolution has relatively minor impact on simulated cloud properties. However, one feature that was influence by the resolution study in several models was the diurnal cycle of precipitation. Peaking at a different time from convective precipitation, large-scale precipitation generally increases in high resolution forecasts and modulates the total precipitation diurnal cycle. Overall, the study emphasizes the importance of more environmental responsive convective parameterizations to capture various types of convection and the substantial diversity among large-scale cloud and precipitation schemes in current GAMs. This experiment has also demonstrated itself to be a very useful testbed for those developing cloud and convection schemes in these models.
Lin, Yanluan; Donner, Leo J.; Petch, Jon C.; Bechtold, P.; Boyle, James; Klein, Stephen A.; Komori, T.; Wapler, K.; Willett, M.; Xie, X.; Zhao, M.; Xie, Shaocheng; McFarlane, Sally A.; Schumacher, Courtney
Sensitivities of Simulated Convective Storms to Environmental CAPE
A set of 225 idealized three-dimensional cloud-resolving simulations is used to explore convective storm behavior in environments with various values of CAPE (450, 800, 2000, and 3200 J kg?1). The simulations show that when CAPE = 2000 J kg?1 or ...
Cody Kirkpatrick; Eugene W. McCaul Jr.; Charles Cohen
Effects of Radiation and Turbulence on the Diabatic Heating and Water Budget of the Stratiform Region of a Tropical Cloud Cluster
A two-dimensional, kinematic model, incorporating ice- and water-cloud microphysics, visible and infrared radiation, and convective adjustment, is used to diagnose the thermodynamic, water vapor, and hydrometeor fields of the stratiform clouds ...
Dean D. Churchill; Robert A. Houze Jr.
Title: Radar-observed convective characteristics during TWP-ICE
Title: Radar-observed convective characteristics during TWP-ICE Title: Radar-observed convective characteristics during TWP-ICE Schumacher, Courtney Texas A&M University Houze, Robert University of Washington May, Peter Bureau or Meteorology Research Centre Frederick, Kaycee Cetrone, Jasmine Vallgren, Andreas Category: Field Campaigns This poster will describe the radar dataset obtained in the Tropical Warm Pool International Cloud Experiment (TWP-ICE), which is to take place 20 January - 14 February 2006 in the vicinity of Darwin, Australia. We will describe the convective systems observed during the project by two scanning C-band Doppler radars, one of which will provide dual-polarization measurements, and ARM's vertically pointing cloud radar and lidar installations. In addition, we will discuss the potential for combining
The Initiation of Moist Convection at the Dryline: Forecasting Issues from aCase Study Perspective
The processes that force the initiation of deep convection along the dryline are inferred from special mesoscale observations obtained during the 1991 Central Oklahoma Profiler Studies project, the Verification of the Origins of Rotation in ...
Conrad L. Ziegler; Erik N. Rasmussen
Submonthly Convective Variability over South America and the South Atlantic Convergence Zone
Relationships between deep convection over South America and the atmospheric circulation are examined, with emphasis on submonthly variations of the South Atlantic convergence zone (SACZ) during austral summer. Outgoing longwave radiation (OLR) ...
Brant Liebmann; George N. Kiladis; JoséA. Marengo; Tércio Ambrizzi; John D. Glick
Convection and Easterly Wave Structures Observed in the Eastern Pacific Warm Pool during EPIC-2001
During September–October 2001, the East Pacific Investigation of Climate Processes in the Coupled Ocean–Atmosphere System (EPIC-2001) intertropical convergence zone (ITCZ) field campaign focused on studies of deep convection in the warm-pool ...
Walter A. Petersen; Robert Cifelli; Dennis J. Boccippio; Steven A. Rutledge; Chris Fairall
Horizontal Structure and Seasonality of Large-Scale Circulations Associated with Submonthly Tropical Convection
The relationship between deep tropical convection and large-scale atmospheric circulation in the 6–30-day period range is examined. Regression relationships between filtered outgoing longwave radiation at various locations in the Tropics and 200- ...
George N. Kiladis; Klaus M. Weickmann
A Summary of Convective-Core Vertical Velocity Properties Using ARM UHF Wind Profilers in Oklahoma
This study presents a summary of the properties of deep convective updraft and downdraft cores over the central plains of the United States, accomplished using a novel and now-standard Atmospheric Radiation Measurement Program (ARM) scanning mode ...
Scott E. Giangrande; Scott Collis; Jerry Straka; Alain Protat; Christopher Williams; Steven Krueger
Convective Forcing in the Intertropical Convergence Zone of the Eastern Pacific
One of the goals of the East Pacific Investigation of Climate, year 2001 process study (EPIC2001), was to understand the mechanisms controlling the forcing of deep atmospheric convection over the tropical eastern Pacific. An intensive study was ...
David J. Raymond; G. B. Raga; Christopher S. Bretherton; John Molinari; Carlos López-Carrillo; Željka Fuchs
Wind and Temperature Profiles in the Radix Layer: The Bottom Fifth of the Convective Boundary Layer
In the middle of the convective atmospheric boundary layer is often a deep layer of vertically uniform wind speed (MUL), wind direction, and potential temperature (?UL). A radix layer is identified as the whole region below this uniform layer, ...
Edi Santoso; Roland Stull
Observations with Moored Acoustic Doppler Current Profilers in the Convection Regime in the Golfe du Lion
In the Golfe du Lion, south of France, favorable conditions for deep winter convection exist and were documented by the MEDOC experiments during 1969–75. A renewed investigation of that regime with upward-looking moored acoustic Doppler current ...
Friedrich Schott; Kevin D. Leaman
Intraseasonal and Seasonal-to-Interannual Indian Ocean Convection and Hemispheric Teleconnections
Deep tropical convection over the Indian Ocean leads to intense diabatic heating, a main driver of the climate system. The Northern Hemisphere circulation and precipitation associated with intraseasonal and seasonal-to-interannual components of ...
Andrew Hoell; Mathew Barlow; Roop Saini
Combining Satellite Infrared and Lightning Information to Estimate Warm Season Convective and Stratiform Rainfall
This paper describes and evaluates a satellite rainfall estimation technique that combines infrared and lightning information to estimate precipitation in deep convective systems. The algorithm is developed and tested using seven years (2002-2008) ...
Weixin Xu; Robert F. Adler; Nai-Yu Wang
A Shallow-Convection Parameterization for Mesoscale Models. Part I: Submodel Description and Preliminary Applications
A shallow-convection parameterization suitable for both marine and continental regimes is developed for use in mesoscale models. The scheme is closely associated with boundary layer turbulence processes and can transition to either a deep-...
Aijun Deng; Nelson L. Seaman; John S. Kain
A Summary of Convective Core Vertical Velocity Properties Using ARM UHF Wind Profilers in Oklahoma
This study presents a summary of deep convective updraft and downdraft core properties over the central plains of the United States, accomplished using a novel and now-standard ARM scanning mode for a commercial wind profiler system. A unique ...
CAPE and Convective Events in the Southwest during the North American Monsoon
The relationship between atmospheric stability, measured as CAPE, and deep precipitating convection has been widely studied but is not definitive. In the maritime tropics, CAPE and precipitation are usually inversely correlated. In continental ...
David K. Adams; Enio P. Souza
ARM - Field Campaign - COPS - Initiation of Convection and the
govCampaignsCOPS - Initiation of Convection and the Microphysical govCampaignsCOPS - Initiation of Convection and the Microphysical Properties of Clouds in Orographic Terrain Campaign Links AMF Black Forest Deployment Related Campaigns COPS - AOS Intercomparison 2007.08.09, Jefferson, AMF COPS - ADMIRARI at Black Forest 2007.07.30, Battaglia, AMF COPS - University of Cologne Micromet Station 2007.07.23, Schween, AMF COPS - Cloud Microwave Validation Experiment in Support of CLOWD 2007.06.22, Vogelmann, AMF COPS - WILI Coherent Doppler Wind Lidar at Black Forest 2007.05.10, Althausen, AMF COPS - Multi Wavelength Raman Lidar (MWL) at Black Forest 2007.05.10, Althausen, AMF COPS - 35.5 GHz Cloud Radar Comparison at Black Forest 2007.05.01, Handwerker, AMF COPS - HATPRO at Black Forest 2007.04.01, Crewell, AMF COPS - Micro-Rain Radar at Black Forest
Aircraft Observations of Convective Systems in the Indian Ocean [EVS Event]
Aircraft Observations of Convective Systems in the Indian Ocean Aircraft Observations of Convective Systems in the Indian Ocean August 23, 2013 Speaker: Bradley Nicholas Guy National Research Council Postdoctoral Fellow NOAA National Severe Storms Laboratory Date: Friday, August 23, 2013 Time: 11:00 a.m. Location: Argonne National Laboratory TCS Building 240 Room 4301 In the DYNAMO (Dynamics of the Madden-Julian Oscillation) field experiment, a large number of measurement platforms were deployed to study environmental and convective cloud system characteristics of the Madden-Julian Oscillation (MJO) initiation region in the Indian Ocean. A mobile platform, the NOAA P-3 instrumented aircraft, sampled intense convective cloud systems, along with the surrounding environment. This presentation will explore the characteristics of mesoscale convective
The Synoptic and Subsynoptic Structure of a Long-Lived Severe Convective System
A long-lived severe convective system in the southern United States from 2–4 May 1978 is documented. The distinguishing feature of the convection was its origin in a region of deep synoptic scale ascent and its subsequent steady motion away from ...
Michael L. Branick; Frank Vitale; Chung-Chieng Lai; Lance F. Bosart
Numerical Simulation of Episodes of Organized Convection in Tropical Northern Africa
A large-domain convection-permitting numerical model is used to simulate episodes of deep convection, which are generated during the day over the Ethiopian Highlands and then propagate westward over the eastern and central Sahel region (5°–20°N) ...
Arlene G. Laing; Stanley B. Trier; Christopher A. Davis
The Relationship between Precipitation and Lightning in Tropical Island Convection: A C-Band Polarimetric Radar Study
One of the primary scientific objectives of the Maritime Continent Thunderstorm Experiment was to study cloud electrification processes in tropical island convection, in particular, the coupling between ice phase precipitation and lightning ...
Lawrence D. Carey; Steven A. Rutledge
A Satellite Method to Identify Structural Properties of Mesoscale Convective Systems Based on the Maximum Spatial Correlation Tracking Technique (MASCOTTE)
A simple, fully automated, and efficient method to determine the structural properties and evolution (tracking) of cloud shields of convective systems (CS) is described. The method, which is based on the maximum spatial correlation tracking ...
Leila M. V. Carvalho; Charles Jones
The effects of imposed stratospheric cooling on the maximum intensity of tropical cyclones in axisymmetric radiative-convective equilibrium
The effects of stratospheric cooling and sea surface temperature (SST) warming on tropical cyclone (TC) potential intensity (PI) are explored using an axisymmetric cloud-resolving model run to radiative-convective equilibrium (RCE). Almost all ...
Hamish A. Ramsay
Interaction of Low-Level Flow with the Western Ghat Mountains and Offshore Convection in the Summer Monsoon
Seven-year averaged values of percent frequency of occurrence of highly reflective cloud for the months June, July, and August indicate that offshore convection is a major component of the cloudiness of the southwest monsoon. Principal areas of ...
Robert L. Grossman; Dale R. Durran
Aerosol Size Spectra in a Convective Marine Layer with Stratus: Results of Airborne Measurements near San Nicolas Island, California
Airborne measurements of the aerosol size spectra n (r) (r is radius) were made in a vertical plane extending northeastward 18 km from San Nicolas Island, California. Thin, patchy, stratus clouds were present in a deepening convective marine ...
V. Ray Noonkester
Satellite-Model Coupled Analysis of Convective Potential in Florida with VAS Water Vapor and Surface Temperature Data
A system for time-continuous mesoscale weather analysis is applied to a study of convective cloud development in central Florida. The analysis system incorporates water vapor concentrations and surface temperatures retrieved from infrared VISSR (...
Alan E. Lipton; George D. Modica; Scot T. Heckman; Arthur J. Jackson
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
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...
Uncertainty Quantification and Parameter Tuning in the CAM5 Zhang-McFarlane Convection Scheme and Impact of Improved Convection on the Global Circulation and Climate
In this study, we applied an uncertainty quantification (UQ) technique to improve convective precipitation in the global climate model, the Community Atmosphere Model version 5 (CAM5), in which the convective and stratiform precipitation partitioning is very different from observational estimates. We examined the sensitivity of precipitation and circulation to several key parameters in the Zhang-McFarlane deep convection scheme in CAM5, using a stochastic importance-sampling algorithm that can progressively converge to optimal parameter values. The impact of improved deep convection on the global circulation and climate was subsequently evaluated. Our results show that the simulated convective precipitation is most sensitive to the parameters of the convective available potential energy consumption time scale, parcel fractional mass entrainment rate, and maximum downdraft mass flux fraction. Using the optimal parameters constrained by the observed Tropical Rainfall Measuring Mission, convective precipitation improves the simulation of convective to stratiform precipitation ratio and rain-rate spectrum remarkably. When convection is suppressed, precipitation tends to be more confined to the regions with strong atmospheric convergence. As the optimal parameters are used, positive impacts on some aspects of the atmospheric circulation and climate, including reduction of the double Intertropical Convergence Zone, improved East Asian monsoon precipitation, and improved annual cycles of the cross-equatorial jets, are found as a result of the vertical and horizontal redistribution of latent heat release from the revised parameterization. Positive impacts of the optimal parameters derived from the 2 simulations are found to transfer to the 1 simulations to some extent.
Yang, Ben; Qian, Yun; Lin, Guang; Leung, Lai-Yung R.; Rasch, Philip J.; Zhang, Guang J.; McFarlane, Sally A.; Zhao, Chun; Zhang, Yaocun; Wang, Hailong; Wang, Minghuai; Liu, Xiaohong
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
Cloud-to-Ground Lightning Observations from TOGA COARE: Selected Results and Lightning Location Algorithms
Recently, observations of electrified oceanic convection and associated cloud-to-ground (CG) lightning were obtained over the tropical western Pacific Ocean during TOGA COARE (Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response ...
Walter A. Petersen; Steven A. Rutledge; Richard E. Orville
Application of Wavelet Transform to Meteosat-Derived Cold Cloud Index Data over South America
Cold cloud index (CCI) data derived from Meteosat infrared imagery are used to detect periodicities in convective activity in South America. The generally used Fourier transform (FT) cannot provide time-localized information but gives information ...
Srinivasa Rao Chapa; Vadlamudi Brahmananda Rao; Gannabathula Sri Sesha Durga Prasad
Comparison of Simulated and Observed Continental Tropical Anvil Clouds and Their Radiative Heating Profiles
Vertically pointing millimeter-wavelength radar observations of anvil clouds extending from mesoscale convective systems (MCSs) that pass over an Atmospheric Radiation Measurement Program (ARM) field site in Niamey, Niger, are compared to anvil ...
Scott W. Powell; Robert A. Houze Jr.; Anil Kumar; Sally A. McFarlane
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
Cloud Clusters and Tropical Cyclogenesis: Developing and Nondeveloping Systems and Their Large-Scale Environment
Tropical cyclone (TC) genesis occurs only when there is persistent, organized convection. The question of why some cloud clusters develop into a TC and others do not remains unresolved. This question cannot be addressed adequately without studying ...
Brandon W. Kerns; Shuyi S. Chen
Cloud Variability over the Indian Monsoon Region as Observed from Satellites
This study focuses on documenting the seasonal progression of the Asian monsoon by analyzing clouds and convection in the pre-, peak-, and postmonsoon seasons. This effort was possible as a result of the movement of Meteosat-5 over the Indian ...
Margaret M. Wonsick; Rachel T. Pinker; Yves Govaerts
Multiparameter Radar and Aircraft Study of Raindrop Spectral Evolution in Warm-based Clouds
Radar measurements of reflectivity differential reflectivity, and X-band (3-cm wavelength) specific attenuation are used to inter some microphysical characteristics of warm-based convective clouds with emphasis on raindrop spectral evolution. The ...
V. N. Bringi; D. A. Burrows; S. M. Menon
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
An Objective Algorithm for Detecting and Tracking Tropical Cloud Clusters: Implications for Tropical Cyclogenesis Prediction
An algorithm to detect and track global tropical cloud clusters (TCCs) is presented. TCCs are organized large areas of convection that form over warm tropical waters. TCCs are important because they are the "seedlings" that can evolve into ...
Christopher C. Hennon; Charles N. Helms; Kenneth R. Knapp; Amanda R. Bowen
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
Effects of Cloud Seeding in West Texas: Additional Results and New Insights
Additional results and new insights have been obtained regarding the effect of randomized dynamic seeding of supercooled convective clouds in west Texas. These have resulted in a revised conceptual model that aids in understanding the new results ...
Daniel Rosenfeld; William L. Woodley
An Airborne Precipitation Cloud Particle Charge Measurement Device and Analysis System
A system is described for measurement and analysis of precipitation particle charge from an aircraft in the highly variable and harsh environment of a convective cloud. A compromise, practical instrument design enables particle charge and sign to ...
C. P. R. Saunders; R. L. Pitter; B. A. Gardiner; J. Hallett
Final Report on Evaluating the Representation and Impact of Convective Processes in the NCAR Community Climate System Model
Convection and clouds affect atmospheric temperature, moisture and wind fields through the heat of condensation and evaporation and through redistributions of heat, moisture and momentum. Individual clouds have a spatial scale of less than 10 km, much smaller than the grid size of several hundred kilometers used in climate models. Therefore the effects of clouds must be approximated in terms of variables that the model can resolve. Deriving such formulations for convection and clouds has been a major challenge for the climate modeling community due to the lack of observations of cloud and microphysical properties. The objective of our DOE CCPP project is to evaluate and improve the representation of convection schemes developed by PIs in the NCAR (National Center for Atmospheric Research) Community Climate System Model (CCSM) and study its impact on global climate simulations. • The project resulted in nine peer-reviewed publications and numerous scientific presentations that directly address the CCPP's scientific objective of improving climate models. • We developed a package of improved convection parameterization that includes improved closure, trigger condition for convection, and comprehensive treatment of convective momentum transport. • We implemented the new convection parameterization package into several versions of the NCAR models (both coupled and uncoupled). This has led to 1) Improved simulation of seasonal migration of ITCZ; 2) Improved shortwave cloud radiative forcing response to El Nińo in CAM3; 3) Improved MJO simulation in both uncoupled and coupled model; and 4) Improved simulation of ENSO in coupled model. • Using the dynamic core of CCM3, we isolated the dynamic effects of convective momentum transport. • We implemented mosaic treatment of subgrid-scale cloud-radiation interaction in CCM3.
X. Wu, G. J. Zhang
Horizontal Convective Rolls in Cold Air over Water: Buoyancy Characteristics of Coherent Plumes Detected by an Airborne Radar
Aircraft and airborne cloud radar data are used to describe the vertical structure of the convective boundary layer (CBL) during cold-air outbreaks over Lake Michigan in January 2004. Two days with mesoscale cloud street structure and a day with ...
Qiong Yang; Bart Geerts
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
Convective and Symmetric Instabilities and Their Effects on Precipitation: Seasonal Variations in Central Alberta during 1990 and 1991
Sounding data from central Alberta were analyzed to assess whether the atmosphere indicated deep layers that were susceptible to convective or moist symmetric instability. The observations consisted of 1460 balloon soundings covering the 2-yr ...
G. W. Reuter; N. Aktary
Intense Convective Storms with Little or No Lightning over Central Arizona: A Case of Inadvertent Weather Modification?
On 20/21 August 1993, deep convective storms occurred across much of Arizona, except for the southwestern quarter of the state. Several storms were quite severe, producing downbursts and extensive wind damage in the greater Phoenix area during ...
Robert A. Maddox; Kenneth W. Howard; Charles L. Dempsey
Convective Activity over Africa and the Tropical Atlantic Inferred from 20 Years of Geostationary Meteosat Infrared Observations
A 20-yr (1986–2005) time series of Meteosat Visible and Infrared Imager (MVIRI) geostationary infrared observations was used to study deep convection over Africa and the tropical Atlantic. The 20-yr time period is covered by six consecutive ...
Ralf Bennartz; Marc Schroeder
Surface-Based Convective Potential in the Contiguous United States in a Business-as-Usual Future Climate
To date, neither observational studies nor direct climate model simulations have been able to document trends in the frequency or severity of deep moist convection associated with global climate change. The lack of such evidence is not unexpected ...
Sara L. Van Klooster; Paul J. Roebber
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
Anvil Characteristics as Seen by C-POL during the Tropical Warm Pool International Cloud Experiment (TWP-ICE)
The Tropical Pacific Warm Pool International Cloud Experiment (TWP-ICE) took place in Darwin, Australia, in early 2006. C-band radar data were used to characterize tropical anvil (i.e., thick, nonprecipitating cloud associated with deep ...
Kaycee Frederick; Courtney Schumacher
Simulation of the North American Monsoon by the NCAR CCM3 and Its Sensitivity to Convection Parameterization
Simulation of the North American Monsoon by the NCAR CCM3 and Its Sensitivity to Convection of the North American summer monsoon. In a control simulation, the ZhangÂMcFarlane deep convection scheme for simulating the North American monsoon is investigated. Model validation relies on hourly precipitation rates
Zhang, Guang Jun
Predictions of convective losses from a solar cavity receiver
Convective losses arising from buoyancy driven flow were calculated for a two-dimensional model simulating a solar cavity receiver. The TEMPEST code, capable of fully three-dimensional coupled thermal-hydraulic transient calculations, was used for the simulation. Predicted velocity and temperature results for a 2.59 m deep by 2.88 m high rectangular cavity with an aperture opening of 1.72 m were used to determine convective losses for prescribed interior wall temperatures and cavity orientation. Velocity vector and temperature isotherm plots were used to analyze flow characteristics.
Eyler, L.L.
Convection Patterns in a Pond
Unusual convection patterns were observed in snow-slush an a pond in Seattle, Wash., during January 1980 and again during February 1981. The patterns are reminiscent of spoke-type convection discovered experimentally by Busse and Whitehead (1974)...
Kristina B. Katsaros
that convective heat transfer processes are These computer~vective .part of the heat transfer process ? elng studled*of convect i ve heat transfer processes, the behavior of a
Gadgil, A.
LES Simulations of Roll Clouds Observed During Mixed- Phase Arctic Cloud Experiment
Roll clouds, and associated roll convection, are fairly common features of the atmospheric boundary layer. While these organized cumuliform clouds are found over many regions of the planet, they are quite ubiquitous near the edge of the polar ice sheets. In particular, during periods of off-ice flow, when cold polar air flows from the ice pack over the relatively warm ocean water, strong boundary layer convection develops along with frequent rolls. According to Bruemmer and Pohlman (2000), most of the total cloud cover in the Arctic is due to roll clouds. In an effort to examine the influences of mixed-phase microphysics on the boundary layer evolution of roll clouds during off-ice flow, Olsson and Harrington (2000) used a 2D mesoscale model coupled to a bulk microphysical scheme (see Section 2). Their results showed that mixed-phase clouds produced more shallow boundary layers with weaker turbulence than liquid-phase cases. Furthermore, their results showed that because of th e reduced turbulent drag on the atmosphere in the mixed-phase case, regions of mesoscale divergence in the marginal ice-zone were significantly affected. A follow-up 2D study (Harrington and Olsson 2001) showed that the reduced turbulent intensity in mixed-phase cases was due to precipitation. Ice precipitation caused downdraft stabilization which fed back and caused a reduction in the surface heat fluxes. In this work, we extend the work of Olsson and Harrington (2000) and Harrington and Olsson (2001) by examining the impacts of ice microphysics on roll convection. We will present results that illustrate how microphysics alters roll cloud structure and dynamics.
Greenberg, S.D.; Harrington, J.Y.; Prenni, A.; DeMott, P.
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
Evolution of the Population of Precipitating Convective Systems over the Equatorial Indian Ocean in Active Phases of the Madden–Julian Oscillation
Three-dimensional radar reflectivity fields from a dual-wavelength Doppler polarimetric radar (S-PolKa) deployed in the equatorial Indian Ocean are used to evaluate the composition of the population of convective cloud elements during active ...
Manuel D. Zuluaga; Robert A. Houze Jr.
Evolution of the Population of Precipitating Convective Systems over the Equatorial Indian Ocean in Active Phases of the Madden-Julian Oscillation
Three-dimensional radar-reflectivity fields from a dual-wavelength Doppler polarimetric radar (S-PolKa) deployed in the equatorial Indian Ocean are used to evaluate the composition of the population of convective cloud elements during active ...
Manuel D. Zuluaga; Robert A. Houze; Jr.
We present an analytic one-dimensional radiative-convective model of the thermal structure of planetary atmospheres. Our model assumes that thermal radiative transfer is gray and can be represented by the two-stream approximation. Model atmospheres are assumed to be in hydrostatic equilibrium, with a power-law scaling between the atmospheric pressure and the gray thermal optical depth. The convective portions of our models are taken to follow adiabats that account for condensation of volatiles through a scaling parameter to the dry adiabat. By combining these assumptions, we produce simple, analytic expressions that allow calculations of the atmospheric-pressure-temperature profile, as well as expressions for the profiles of thermal radiative flux and convective flux. We explore the general behaviors of our model. These investigations encompass (1) worlds where atmospheric attenuation of sunlight is weak, which we show tend to have relatively high radiative-convective boundaries; (2) worlds with some attenuation of sunlight throughout the atmosphere, which we show can produce either shallow or deep radiative-convective boundaries, depending on the strength of sunlight attenuation; and (3) strongly irradiated giant planets (including hot Jupiters), where we explore the conditions under which these worlds acquire detached convective regions in their mid-tropospheres. Finally, we validate our model and demonstrate its utility through comparisons to the average observed thermal structure of Venus, Jupiter, and Titan, and by comparing computed flux profiles to more complex models.
Robinson, Tyler D. [Astronomy Department, University of Washington, Box 351580, Seattle, WA 98195-1580 (United States); Catling, David C., E-mail: email@example.com [Department of Earth and Space Sciences, University of Washington, Box 351310, Seattle, WA 98195-1310 (United States)
5, 1102911054, 2005 Convective gravity
ACPD 5, 11029Â11054, 2005 Convective gravity waves at mid-latitudes Y. G. Choi et al. Title Page Discussions Wind-profiler observations of gravity waves produced by convection at mid-latitudes Y. G. Choi1Â11054, 2005 Convective gravity waves at mid-latitudes Y. G. Choi et al. Title Page Abstract Introduction
Paris-Sud XI, Université de
Feeder-Cell Ingestion of Seeding Aerosol from Cloud Base Determined by Tracking Radar Chaff
Questions of delivery, transport, and dispersion of cloud seeding aerosol in a convective feeder cloud are addressed by using radar chaff as a surrogate for aerosol and tracking it with circular-polarization radar. In a case study, a line source ...
Roger F. Reinking; Brooks E. Martner
The Shape of Large Tropospheric Clouds, or "Very Like a Whale"
Lovejoy (1982) analyzed radar and satellite images of convective clouds and rainbands extending over an area range from 10 to 106 km2 and found the fractal cloud-perimeter dimension to equal 1.35, indicating the presence of a Richardson, three-...
F. A. Gifford
How Does Labrador Sea Water Enter the Deep Western Boundary Current?
Labrador Sea Water (LSW), a dense water mass formed by convection in the subpolar North Atlantic, is an important constituent of the meridional overturning circulation. Understanding how the water mass enters the deep western boundary current (...
Jaime B. Palter; M. Susan Lozier; Kara L. Lavender
DRAFT, last update 5 January 2012 Aerosol cloud-mediated radiative forcing: highly uncertain and
phase and ice processes. Respectively, the parameterization of these processes for GCMs is further away and aerosol parameterizations, but intense research efforts aimed at improving the realism of cloud lower than for the shallow clouds, as the deep clouds are much more complicated, because mixed phase
Wood, Robert
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
Cloud-Resolving Ensemble Simulations of Mediterranean Heavy Precipitating Events: Uncertainty on Initial Conditions and Lateral Boundary Conditions
This study assesses the impact of uncertainty on convective-scale initial conditions (ICs) and the uncertainty on lateral boundary conditions (LBCs) in cloud-resolving simulations with the Application of Research to Operations at Mesoscale (AROME)...
Benoît Vié; Olivier Nuissier; Véronique Ducrocq
Nocturnal Photographs Taken from a U-2 Airplane Looking Down on Tops of Clouds Illuminated by Lightning
Photographs have been taken at night from an airplane at an altitude of 20 km looking directly down on the tops of thunderclouds illuminated by lightning. The hard, cauliflower-like appearance of the clouds gives evidence that strong convective ...
B. Vonnegut; O. H. Vaughan Jr.; M. Brook
Deep Lysimeter
A deep lysimeter including a hollow vessel having a chamber, a fill conduit extending into the chamber through apertures, a semi-permeable member mounted on the vessel and in fluid communication with the fill conduit, and a line connection for retrieving the lysimeter.
Hubbell, Joel M. (Idaho Falls, ID); Sisson, James B. (Idaho Falls, ID)
Precipitation Partitioning, Tropical Clouds, and Intraseasonal Variability in GFDL AM2
A set of Geophysical Fluid Dynamics Laboratory (GFDL) Atmospheric Model version 2 (AM2) sensitivity simulations by varying an entrainment threshold rate to control deep convection occurrence are used to investigate how cumulus parameterization ...
Yanluan Lin; Ming Zhao; Yi Ming; Jean-Christophe Golaz; Leo J. Donner; Stephen A. Klein; V. Ramaswamy; Shaocheng Xie
Refinement, Validation and Application of Cloud-Radiation Parameterization in a GCM
The research performed under this award was conducted along 3 related fronts: (1) Refinement and assessment of parameterizations of sub-grid scale radiative transport in GCMs. (2) Diagnostic studies that use ARM observations of clouds and convection in an effort to understand the effects of moist convection on its environment, including how convection influences clouds and radiation. This aspect focuses on developing and testing methodologies designed to use ARM data more effectively for use in atmospheric models, both at the cloud resolving model scale and the global climate model scale. (3) Use (1) and (2) in combination with both models and observations of varying complexity to study key radiation feedback Our work toward these objectives thus involved three corresponding efforts. First, novel diagnostic techniques were developed and applied to ARM observations to understand and characterize the effects of moist convection on the dynamical and thermodynamical environment in which it occurs. Second, an in house GCM radiative transfer algorithm (BUGSrad) was employed along with an optimal estimation cloud retrieval algorithm to evaluate the ability to reproduce cloudy-sky radiative flux observations. Assessments using a range of GCMs with various moist convective parameterizations to evaluate the fidelity with which the parameterizations reproduce key observable features of the environment were also started in the final year of this award. The third study area involved the study of cloud radiation feedbacks and we examined these in both cloud resolving and global climate models.
Dr. Graeme L. Stephens
convection process and calculate convective heat transferthat convective heat transfer processes are highly dependentheat transfer process being studied* and
Gadgil, Ashok; Bauman, Fred; Kammerud, Ronald
Stabilizing Cloud Feedback Dramatically Expands the Habitable Zone of Tidally Locked Planets
The habitable zone (HZ) is the circumstellar region where a planet can sustain surface liquid water. Searching for terrestrial planets in the HZ of nearby stars is the stated goal of ongoing and planned extrasolar planet surveys. Previous estimates of the inner edge of the HZ were based on one-dimensional radiative-convective models. The most serious limitation of these models is the inability to predict cloud behavior. Here we use global climate models with sophisticated cloud schemes to show that due to a stabilizing cloud feedback, tidally locked planets can be habitable at twice the stellar flux found by previous studies. This dramatically expands the HZ and roughly doubles the frequency of habitable planets orbiting red dwarf stars. At high stellar flux, strong convection produces thick water clouds near the substellar location that greatly increase the planetary albedo and reduce surface temperatures. Higher insolation produces stronger substellar convection and therefore higher albedo, making this phen...
Yang, Jun; Abbot, Dorian S
Rapidly rotating giant planets are usually marked by the existence of strong zonal flows at the cloud level. If the zonal flow is sufficiently deep and strong, it can produce hydrostatic-related gravitational anomalies through distortion of the planet's shape. This paper determines the zonal gravity coefficients, J{sub 2n}, n = 1, 2, 3, ..., via an analytical method taking into account rotation-induced shape changes by assuming that a planet has an effective uniform density and that the zonal flows arise from deep convection and extend along cylinders parallel to the rotation axis. Two different but related hydrostatic models are considered. When a giant planet is in rigid-body rotation, the exact solution of the problem using oblate spheroidal coordinates is derived, allowing us to compute the value of its zonal gravity coefficients J-bar{sub 2n}, n=1,2,3,..., without making any approximation. When the deep zonal flow is sufficiently strong, we develop a general perturbation theory for estimating the variation of the zonal gravity coefficients, {Delta}J{sub 2n}=J{sub 2n}-J-bar{sub 2n}, n=1,2,3,..., caused by the effect of the deep zonal flows for an arbitrarily rapidly rotating planet. Applying the general theory to Jupiter, we find that the deep zonal flow could contribute up to 0.3% of the J{sub 2} coefficient and 0.7% of J{sub 4}. It is also found that the shape-driven harmonics at the 10th zonal gravity coefficient become dominant, i.e., {Delta}J{sub 2n}>=J-bar{sub 2n} for n {>=} 5.
Kong Dali; Zhang Keke [Center for Geophysical and Astrophysical Fluid Dynamics and Department of Mathematical Sciences, University of Exeter, EX4 4QF (United Kingdom); Schubert, Gerald, E-mail: email@example.com, E-mail: firstname.lastname@example.com, E-mail: email@example.com [Department of Earth and Space Sciences, University of California, Los Angeles, CA 90095-1567 (United States)
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
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
Can an E–l Turbulence Closure Simulate Entrainment in Radiatively Driven Convective Boundary Layers?
The simulation of entrainment by an (E–l) turbulent kinetic energy–diagnostic length scale closure model is investigated in a smoke cloud convective boundary layer. The behavior of the E–l scheme is compared with two simple entrainment closures ...
Geert Lenderink; Margreet C. vanZanten; Peter G. Duynkerke
A Trajectory Analysis of Tropical Upper-Tropospheric Moisture and Convection
It is shown that the distribution of upper-tropospheric humidity (UTH) in the cloud-free Tropics can be simulated with a simple model in which air expelled from moist convective regions is dried by subsidence along its trajectory. The ...
Eric P. Salathé Jr.; Dennis L. Hartmann
The Sensitivity of West African Convective Line Water Budgets to Land Cover
This study used a two-dimensional coupled land–atmosphere (cloud resolving) model to investigate the influence of land cover on the water budgets of convective lines in West Africa. Study simulations used the same initial sounding and one of ...
Karen I. Mohr; R. David Baker; Wei-Kuo Tao; James S. Famiglietti