Cloud Ensemble Model Research Articles

Satellite-Surface Perspectives of Air Quality and Aerosol-Cloud Effects on the Environment: An Overview of 7-SEAS/BASELInE

The objectives of 7-SEAS/BASELInE (Seven SouthEast Asian Studies/Biomass-burning Aerosols & Stratocumulus Environment: Lifecycles & Interactions Experiment) campaigns in spring 2013-2015 were to synergize measurements from uniquely distributed ground-based networks (e.g., AERONET, MPLNET) and sophisticated platforms (e.g., SMARTLabs, regional contributing instruments), along with satellite observations/retrievals and regional atmospheric transport/chemical models to establish a critically needed database, and to advance our understanding of biomass-burning aerosols and trace gases in Southeast Asia (SEA). We present a satellite-surface perspective of 7-SEAS/BASELInE and highlight scientific findings concerning: (1) regional meteorology of moisture fields conducive to the production and maintenance of low-level stratiform clouds over land, (2) atmospheric composition in a biomass-burning environment, particularly tracers/markers to serve as important indicators for assessing the state and evolution of atmospheric constituents, (3) applications of remote sensing to air quality and impact on radiative energetics, examining the effect of diurnal variability of boundary-layer height on aerosol loading, (4) aerosol hygroscopicity and ground-based cloud radar measurements in aerosol-cloud processes by advanced cloud ensemble models, and (5) implications of air quality, in terms of toxicity of nanoparticles and trace gases, to human health. This volume is the third 7-SEAS special issue (after Atmospheric Research, vol. 122, 2013; and Atmospheric Environment, vol. 78, 2013) and includes 27 papers published, with emphasis on air quality and aerosol-cloud effects on the environment. BASELInE observations of stratiform clouds over SEA are unique, such clouds are embedded in a heavy aerosol-laden environment and feature characteristically greater stability over land than over ocean, with minimal radar surface clutter at a high vertical spatial resolution. To facilitate an improved understanding of regional aerosol-cloud effects, we envision that future BASELInE-like measurement/modeling needs fall into two categories: (1) efficient yet critical in-situ profiling of the boundary layer for validating remote-sensing/retrievals and for initializing regional transport/chemical and cloud ensemble models, and (2) fully utilizing the high observing frequencies of geostationary satellites for resolving the diurnal cycle of the boundary-layer height as it affects the loading of biomass-burning aerosols, air quality and radiative energetics.

Desenvolvimento de uma parametrização do efeito de rajadas associadas a sistemas convectivos nos fluxos de calor na superfície utilizando Modelagem de Ensemble de Nuvens

Sistemas convectivos precipitantes produzem rajadas a partir de suas correntes descendentes, quando estas atingem a superfície. Tais rajadas têm a capacidade de amplificar os fluxos superficiais de calor sensível e latente, com possíveis consequências para a própria evolução futura da convecção. Modelos de Circulação Geral da Atmosfera e até modelos regionais, ainda que tenham se tornado mais eficientes e robustos, ainda estão muito longe de representarem adequadamente (explicitamente) as nuvens e, portanto, o efeito de intensificação dos fluxos por rajadas não é por eles simulado. Na verdade, tal efeito sequer é parametrizado, na maioria dos casos. No presente trabalho, um CEM (Cloud Ensemble Model), alimentado por forçante de grande escala característico de condições de convecção tropical, foi usado para encontrar uma parametrização que represente a intensificação dos fluxos de calor da superfície por rajadas, por meio de um fator, que é função da taxa de precipitação, do vento resolvido e da resolução espacial do modelo de grande escala. O fator de intensificação possui correlações significativas com o vento resolvido (-0,67 < ρ < -0,46) e a taxa de precipitação (0,65 > ρ > 0,4), que são usadas como variáveis de entrada para calculá-lo. A parametrização foi encontrada a partir do ajuste de parâmetros utilizando os dados de saída das simulações com o CEM.

Sensibilidade de conjuntos de nuvens a variações de parâmetros microfísicos: parte I - simulação de controle

Este trabalho é o primeiro de uma série de quatro artigos, com o objetivo de analisar como variações em parâmetros microfísicos afetam o ciclo de vida de nuvens de fase mista, para diferentes condições de estabilidade vertical, adotando como ferramenta uma versão de "cloud ensemble model" - CEM do Regional Atmospheric Modeling System (RAMS). São utilizados dados do Período de Obervação Intensiva (Intensive Observing Period - IOP) do Tropical Ocean Global / Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA COARE) como forçante para o CEM. Este foi calculado para três regimes, a depender da atividade convectiva: "médio", em que foi considerada a média das variáveis para todo o IOP, "ativo" (convecção mais intensa) e "suprimido" (convecção menos pronunciada). Para cada regime, calculou-se a média das componentes zonal e meridional da velocidade do vento e as forçantes advectivas (horizontal mais vertical) de temperatura potencial e umidade específica. Tais forçantes foram assimiladas pelo CEM em diferentes testes de sensibilidade, descritos nas partes seguintes desta série de artigos. Na parte I, são apresentados os resultados referentes à simulação controle, mostrando como um CEM estabelece uma condição de quase-equilíbrio resultante da resposta da convecção às forçantes de grande escala estacionárias.

Simulation of the fine structure of the 12 July 1996 Stratosphere‐Troposphere Experiment: Radiation, Aerosols and Ozone (STERAO‐A) storm accounting for effects of terrain and interaction with mesoscale flow

Vertical mixing of chemical tracers and optically active constituents by deep convection affects regional and global chemical balances in the troposphere and lower stratosphere. This important process is not explicitly resolved in global and regional models and has to be parameterized. However, mixing depends strongly on the spatial structure, strength, and temporal evolution of the particular storm, complicating parameterization of this important effect in the large‐scale models. To better quantify dynamic fields and associated mixing processes, we simulate a thunderstorm observed on 12 July 1996 during the STERAO‐A (Stratosphere‐Troposphere Experiment: Radiation, Aerosols, and Ozone) Deep Convection field project using the Goddard Cloud Ensemble (GCE) model. The 12 July STERAO‐A storm had very complex temporal and spatial structure. The meteorological environment and evolution of the storm were significantly different than those of the 10 July STERAO‐A storm extensively discussed in previous studies. Our 2‐D and 3‐D GCE model runs with uniform one‐sounding initialization were unable to reproduce the full life cycle of the 12 July storm observed by the CHILL radar system. To describe the storm evolution, we modified the 3‐D GCE model to include the effects of terrain and the capability of using nonuniform initial fields. We conducted a series of numerical experiments and reproduced the observed life cycle and fine spatial structure of the storm. The main characteristics of the 3‐D simulation of the 12 July storm were compared with observations, with 2‐D simulations of the same storm, and with the evolution of the 10 July storm. The simulated 3‐D convection appears to be stronger and more realistic than in our 2‐D simulations. Having developed in a less unstable environment than the 10 July 1996 STERAO‐A storm, our simulation of the 12 July storm produced weaker but sustainable convection that was significantly fed by wind shear instability in the lower troposphere. The time evolution, direction, and speed of propagation of the storm were determined by interaction with the nonuniform background mesoscale flow. For example, storm intensity decreased drastically when the storm left the region with large convective available potential energy. The model appears to be successful in reproducing the rectangular four‐cell structure of the convection. The distributions of convergence, vertical vorticity, and position of the inflow level in the later single‐cell regime compare favorably with the airborne Doppler radar observations. This analysis allowed us to better understand the role of terrain and mesoscale circulation in the development of a midlatitude deep convective system and associated convective mixing. Wind, temperature, hydrometeor, and turbulent diffusion coefficient data from the cloud model simulations were provided for off‐line 3‐D cloud‐scale chemical transport simulations discussed in the companion paper by DeCaria et al. (2005).

Solar radiative biases in deep convective regimes: Possible implications for dynamical feedback

There is increasing evidence that interactions between radiation and convectively determined water vapour and cloud fields can have a significant dynamical impact on the tropical circulation. However, the use of a one-dimensional (1D) independent column method for the calculation of solar fluxes in cloud-resolving or mesoscale models could possibly misrepresent this feedback. This is investigated by calculating 1D and full three-dimensional (3D) solar fluxes through a 3D field of deep convective clouds generated using a high-resolution cloud-resolving model, and diagnosing the clear-sky subsidence velocities required to balance this if a state of radiative convective equilibrium were to exist. The mean clear-sky solar radiative heating rate is found to change by up to 15%. At low sun angles the shading of the clear-sky regions implies a reduction of net clear-sky heating rates. In contrast, at higher solar elevations the scattering effect dominates shading and the clear-sky heating rates are enhanced, implying an enhancement of the diurnal cycle. However, since the 1D/3D heating-rate differences in the clear sky increase smoothly from zero at the tropopause to their maximum value near the surface, the vertical gradient and thus the impact on the vertical profile of entrainment and detrainment into the convective regions is negligibly small. This implies that the strong radiative dynamical feedbacks so far documented in cloud-ensemble models cannot be discounted on the grounds of their use of an independent column calculation for the solar radiative transfer. That said, the substantial bias noted in surface downward solar fluxes could result in a substantial impact in convective organization if an interactive land surface were used as a lower boundary condition. Copyright © 2003 Royal Meteorological Society

Cloud Models: Their Evolution and Future Challenges

A review of convective cloud modeling spanning the period from the days of the NOAA Experimental. Meteorology Laboratory (EML) in the late 1960s to 2000 is presented. The intent is to illustrate the evolution of cloud models from the one-dimensional parcel-type models to the current generation of three-dimensional convective storm models and cloud ensemble models. Moreover, it is shown that Dr. Joanne Simpson played a pivotal role in the evolution of cloud models from the very first models to current generation cloud ensemble models. It is also shown that the first concept of the Regional Atmospheric Modeling System (RAMS) began while Drs. Cotton and Pielke worked under Dr. Simpson’s supervision at EML. It is then illustrated how far cloud modeling has come with recent applications of RAMS to atmospheric research and numerical weather prediction. The chapter concludes with an outline of the major limitations of current generation convective cloud models.

Parameterization of Wind Gustiness for the Computation of Ocean Surface Fluxes at Different Spatial Scales

Analysis of the Goddard cloud-ensemble (GCE) model output forced by observational data over the tropical western Pacific and eastern tropical North Atlantic has shown that ocean surface latent and sensible heat fluxes averaged in a typical global-model grid box are reproduced well using bulk algorithms with grid-box-average scalar wind speed but could be significantly underestimated under weak wind conditions using average vector wind speed. This is consistent with previous observational and modeling studies. The difference between scalar and vector wind speeds represents the subgrid wind variability (or wind gustiness) that is contributed by boundary layer large eddies, convective precipitation, and cloudiness. Based on the GCE data analysis for a case over the tropical western Pacific, a simple parameterization for wind gustiness has been developed that considers the above three factors. This scheme is found to fit well the GCE data for two other cases over the tropical western Pacific and eastern tropical North Atlantic. Its fit is also much better than that of the traditional approach that considers the contribution to wind gustiness by boundary layer large eddies alone. A simple formulation has also been developed to account for the dependence of the authors' parameterization on spatial scales (or model grid size). Together, the preliminary parameterization and formulation can be easily implemented into weather and climate models with various horizontal resolutions.

Entropy Budget of an Atmosphere in Radiative–Convective Equilibrium. Part I: Maximum Work and Frictional Dissipation

Abstract The entropy budget of an atmosphere in radiative–convective equilibrium is analyzed here. The differential heating of the atmosphere, resulting from surface heat fluxes and tropospheric radiative cooling, corresponds to a net entropy sink. In statistical equilibrium, this entropy sink is balanced by the entropy production due to various irreversible processes such as frictional dissipation, diffusion of heat, diffusion of water vapor, and irreversible phase changes. Determining the relative contribution of each individual irreversible process to the entropy budget can provide important information on the behavior of convection. The entropy budget of numerical simulations with a cloud ensemble model is discussed. In these simulations, it is found that the dominant irreversible entropy source is associated with irreversible phase changes and diffusion of water vapor. In addition, a large fraction of the frictional dissipation results from falling precipitation, and turbulent dissipation accounts fo...

The Effect of Vertical Wind Shear on Radiative–Convective Equilibrium States

Using a three-dimensional cloud ensemble model, a systematic exploration is undertaken of radiative–convective equilibrium states as a function of the structure and magnitude of an imposed background flow with vertical shear. In such simulations, mesoscale organization appears naturally, independent of the particulars of the initial condition. As the magnitude of an imposed low-level shear increases, the convection becomes increasingly organized in lines or arcs, propagating broadly downshear, as predicted by earlier work. When the shear is very strong, the convection tends to organize into lines at an angle to the shear, such that the line-normal component is not far from its theoretical optimal value. Midlevel shear favors shear-parallel lines, but if it occurs in conjunction with sufficiently strong low-level shear, the convection can become very strongly organized into lines or arcs generally orthogonal to the low-level shear. Optimal organization occurs when the depth of the shear layer is comparable to that of the cold pools associated with the convective downdrafts. As the vertical shear is increased, the domain-averaged convective available potential energy (CAPE) at first increases but then decreases at stronger shear values. Associated with these changes, the lower to middle troposphere becomes drier at low shear values and more humid when the shear is strong. This relationship between humidity and CAPE is broadly consistent with recently developed CAPE theories. The authors also confirm previous work that shows that the transport of momentum by the simulated convection, though usually down the gradient of the background flow, is nonlocal in character. Finally, some simulations are performed with an imposed hodograph taken from a tropical cyclone. Convective arcs form with an orientation similar to observed outer spiral bands, but the simulated bands propagate more rapidly than observed, perhaps because of a dry middle troposphere in the simulations.

Genesis and Evolution of Hierarchical Cloud Clusters in a Two-Dimensional Cumulus-Resolving Model

Abstract A two-dimensional cloud ensemble model is integrated over a basin-scale domain with prescribed sea surface temperature (SST), to study the formation and evolution of cloud clusters over a large-scale warm pool. Neither a basic zonal flow is prescribed nor is a single perturbation initially given. The results show that deep convective clouds appear in hierarchical clustered patterns and are limited to the area of warm SST above 28°C. The most fundamental cloud cluster in the model has a horizontal scale of a few hundred kilometers, in which new cumulus clouds are generated at the leading edge of a propagating surface cold-air pool—the “gust front.” It may last for days and propagate for a long distance if the background flow is broad and persistent as is the case in the low-level convergence zone of the SST-induced background flow. The largest hierarchical propagating cloud systems in the model have horizontal scales up to 3000 km and consist of up to four cloud clusters that are generally of gust...

Sensitivity analysis of airborne microwave retrieval of stratiform precipitation to the melting layer parameterization

A sensitivity analysis for airborne microwave passive and active retrievals of hydrometeor profiles with respect to melting-layer parameterizations is carried out using synthetic data. The parameterizations of the melting layer include the effects of snow density, particle size distributions of hydrometeors as well as different permittivity models for mixed-phase particles. The hydrometeor profiles are obtained from a two-dimensional cloud ensemble model simulating a convective-stratiform rainfall event over the East Mediterranean sea. The statistical analysis reveals that the Maxwell-Garnett mixing formulas with water matrix and ice inclusions may be chosen for graupel, while a new permittivity model from Meneghini and Liao is suitable for snowflakes. A new Bayesian inversion framework is set up for both airborne microwave radiometric, radar, and combined radar-radiometer retrievals of hydrometeor profiles. Using the cloud profiles as control training data set, a numerical analysis was carried out by testing the inversion algorithms on each melting model data set. Results are discussed in terms of estimate sensitivity, defined as the statistical deviation bounds of the retrieved profiles from the control case ones. Relatively high values of estimate sensitivity to the melting-layer parameterizations are found for all hydrometeor species, especially for low snow-density and Maxwell-Garnett dielectric model test cases. The need of including various melting-layer characterizations within a comprehensive training data set and its implications for model-based Bayesian retrieval algorithms is finally argued and numerically tested.

Explicit Simulation of Midlatitude Cumulus Ensembles: Comparison with ARM Data

Abstract This study describes some results from several simulations of cumulus ensembles at the Southern Great Plains site of the Atmospheric Radiation Measurement (ARM) program during the July 1995 Intensive Observation Period (IOP). A 2D cloud ensemble model (CEM) is used to simulate the macroscopic properties of midlatitude cumulus ensembles. The observed large-scale, horizontal advective tendencies and large-scale vertical velocity or the total advective tendencies are used to drive the CEM, in addition to nudging of the simulated, domain-averaged horizontal wind components toward the observed winds. A detailed comparison with available observations and tropical convection is made in this study. In general, the CEM-simulated results agree reasonably well with the available observations from the July 1995 IOP. The differences between simulations and observations are, however, much larger than those obtained in tropical cases, especially those based on the Global Atmospheric Research Program Atlantic Tr...

A comparison of single column model simulations of summertime midlatitude continental convection

Eleven different single‐column models (SCMs) and one cloud ensemble model (CEM) are driven by boundary conditions observed at the Atmospheric Radiation Measurement (ARM) program southern Great Plains site for a 17 day period during the summer of 1995. Comparison of the model simulations reveals common signatures identifiable as products of errors in the boundary conditions. Intermodel differences in the simulated temperature, humidity, cloud, precipitation, and radiative fluxes reflect differences in model resolution or physical parameterizations, although sensitive dependence on initial conditions can also contribute to intermodel differences. All models perform well at times but poorly at others. Although none of the SCM simulations stands out as superior to the others, the simulation by the CEM is in several respects in better agreement with the observations than the simulations by the SCMs. Nudging of the simulated temperature and humidity toward observations generally improves the simulated cloud and radiation fields as well as the simulated temperature and humidity but degrades the precipitation simulation for models with large temperature and humidity biases without nudging. Although some of the intermodel differences have not been explained, others have been identified as model problems that can be or have been corrected as a result of the comparison.

A Sensitivity Study of Radiative–Convective Equilibrium in the Tropicswith a Convection-Resolving Model

Statistical-equilibrium (SE) states of radiative‐convective systems in tropical oceanic conditions are simulated with a cloud ensemble model (CEM) in this study. Typical large-scale conditions from the Marshall Islands and the eastern tropical Atlantic regions are used to drive the CEM. The simulated SE precipitable water, column temperature, and relative humidity are only slightly higher than those of the observed mean states in both regions when time-invariant large-scale total advective cooling and moistening effects are imposed from observations. They are much higher than the observed if time-invariant observed large-scale ascent is imposed for the Marshall Islands region (i.e., ignoring horizontal advective effects). Compared with results from two similar studies, this SE state is somewhere between the cold/dry regime by Sui et al. and the warm/humid regime by Grabowski et al. Temporal variations of the imposed large-scale vertical motion that allows for subsidence make the SE state colder and drier. It remains about the same, however, if the magnitude of the imposed large-scale vertical motion is halved. The SE state is also colder and drier if solar radiation is absent. In general, all the SE states show that wet columns are thermally more stable (unstable) and dry columns are thermally more unstable (stable) in the lower (upper) troposphere. Column budget analyses are performed to explore the differences among the simulations performed in this study and among the different studies.

Some effects of cloud–aerosol interaction on cloud microphysics structure and precipitation formation: numerical experiments with a spectral microphysics cloud ensemble model

A spectral microphysics Hebrew University Cloud Model (HUCM) is used to evaluate some effects of cloud–aerosol interaction on mixed-phase cloud microphysics and aerosol particle size distribution in the region of the Eastern Mediterranean coastal circulation. In case of a high concentration of aerosol particles (APs), the rate of warm rain formation is several times lower, a significant fraction of droplets ascends above the freezing level. These drops produce a large amount of comparably small graupel particles and ice crystals. The warm rain from these clouds is less intense as compared to clouds with low drop concentration. At the same time, melted rain from clouds with high droplet concentration is more intense than from low drop concentration clouds. Melted rain can take place downwind at a distance of several tens of kilometers from the convective zone. It is shown that APs entering clouds above the cloud base influence the evolution of the drop size spectrum and the rate of rain formation. The chemical composition of APs influences the concentration of nucleated droplets and, therefore, changes accumulated rain significantly (in our experiments these changes are of 25–30%). Clouds in a coastal circulation influence significantly the concentration and size distribution of APs. First, they decrease the concentration of largest APs by nucleation scavenging. In our experiments, about 40% of APs were nucleated within clouds. The remaining APs are transported to middle levels by cloud updrafts and then enter the land at the levels of 3 to 7 km. In our experiments, the concentration of small APs increased several times at these levels. The cut off APs spectrum with an increased concentration of small APs remains downwind of the convective zone for several of tens and even hundreds of kilometers. The schemes of drop nucleation (based on the dependence of nucleated drop concentration on supersaturation in a certain power) and autoconversion (based on the Kessler formula) are unsuitable for an adequate description of cloud–aerosol interaction. The Kessler formula predicts an incorrect tendency in the rate of raindrop formation while increasing APs' concentration. Prediction errors concerning the rate of raindrop formation can easily result in a 10-fold increase. It indicates that the spectral (bin) microphysics scheme (or parameterizations based on the bin schemes) can be used for an adequate description of cloud–aerosol interaction.

Atmospheric Solar Heating in Minor Absorption Bands

Solar radiation is the primary source of energy driving atmospheric and oceanic circulations. Concerned with the huge computing time required for computing radiative transfer in weather and climate models, solar heating in minor absorption bands has often been neglected. The individual contributions of these minor bands to the atmospheric heating is small, but collectively they are not negligible. The solar heating in minor bands includes the absorption due to water vapor in the photosynthetically active radiation (PAR) spectral region from 14284/cm to 25000/cm, the ozone absorption and Rayleigh scattering in the near infrared, as well as the O2 and CO2 absorption in a number of weak bands. Detailed high spectral- and angular-resolution calculations show that the total effect of these minor absorption is to enhance the atmospheric solar heating by approximately 10%. Depending upon the strength of the absorption and the overlapping among gaseous absorption, different approaches are applied to parameterize these minor absorption. The parameterizations are accurate and require little extra time for computing radiative fluxes. They have been efficiently implemented in the various atmospheric models at NASA/Goddard Space Flight Center, including cloud ensemble, mesoscale, and climate models.

Impact of the horizontal wind profile on the convective transport of chemical species

The impact of the vertical profile of the horizontal wind in the troposphere and lower stratosphere on the vertical transport of chemical species induced by deep convective events has been studied using a two‐dimensional cloud ensemble model. Seven horizontal wind profiles, including one observed during the Central and Equatorial Pacific Experiment (CEPEX) have been chosen. These represent typical wind profiles over the tropical Pacific including upper level westerly and easterly cases and have been applied to the model as initial conditions to carry out the sensitivity runs. We have found that the pattern of the shear in the horizontal wind in the vicinity of the tropopause plays a significant role in controlling the development of deep convective clouds. As a result, the fluxes of chemical species from the planetary boundary layer to the free troposphere and from the free troposphere to the lower stratosphere are very different for different assumed profiles. It has been found specifically that a moderate wind shear crossing tropopause favors vertically advective transport of chemical species. Strong positive shear, though enhancing turbulent mixing from the troposphere to the stratosphere, generates the weakest vertically advective transport primarily due to its influence in limiting the vertical development of convective turrets. In addition, we have found that the smoothed wind profile derived from a more fluctuating observed profile produces clear differences in cloud development and associated tracer vertical transport compared with the results of the run with the nonsmoothed profile.

Radiative-convective equilibrium in a three-dimensional cloud-ensemble model

Radiative-convective equilibrium in a three-dimensional cloud-ensemble model

Parameterizations for Cloud Overlapping and Shortwave Single-Scattering Properties for Use in General Circulation and Cloud Ensemble Models

Abstract Parameterizations for cloud single-scattering properties and the scaling of optical thickness in a partial cloudiness condition have been developed for use in atmospheric models. Cloud optical properties are parameterized for four broad bands in the solar (or shortwave) spectrum; one in the ultraviolet and visible region and three in the infrared region. The extinction coefficient, single-scattering albedo, and asymmetry factor are parameterized separately for ice and water clouds. Based on high spectral-resolution calculations, the effective single-scattering coalbedo of a broad band is determined such that errors in the fluxes at the top of the atmosphere and at the surface are minimized. This parameterization introduces errors of a few percent in the absorption of shortwave radiation in the atmosphere and at the surface. Scaling of the optical thickness is based on the maximum-random cloud-overlapping approximation. The atmosphere is divided into three height groups separated approximately by ...

Storm-Associated Microwave Radiometric Signatures in the Frequency Range of 90–220 GHz

Radiometric measurements were made by a millimeter-wave imaging radiometer (MIR) at the frequencies of 89, 150, 183.3 +/- 1, 183.3 +/- 3, 183.3 +/- 7, and 220 GHz aboard the NASA ER-2 aircraft at an altitude of about 20 km over two rainstorms: one in the western Pacific Ocean on 19 January 1993 and another in southern Florida on 5 October 1993. These measurements were complemented by nearly simultaneous observations by other sensors aboard the same aircraft and another aircraft flying along the same path. Analysis of data from these measurements, aided by radiative transfer and radar reflectivity calculations of hydrometeor profiles, which arc generated by a general cloud ensemble model, demonstrates the utility of these frequencies for studying the structure of frozen hydrometeors associated with storms. Particular emphasis is placed on the three water vapor channels near 183.3 GHz. Results show that the radiometric signatures measured by these channels over the storm-associated scattering media bear a certain resemblance to those previously observed over a clear and fairly dry atmosphere with a cold ocean background. Both of these atmospheric conditions are characterized by a small amount of water vapor above a cold background. Radiative transfer calculations were made at these water vapor channels for a number of relative humidity profiles characterizing dry atmospheres over an ocean surface. The results are compared with the measurements to infer some characteristics of the environment near the scattering media. Furthermore, radiometric signatures from these channels display unique features for towering deep convective cells that could be used to identify the presence of such cells in storms.