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A 3-D polarized reversed Monte Carlo radiative transfer model for millimeter and submillimeter passive remote sensing in cloudy atmospheres
- IEEE TRANS GEOSCI REMOTE SENS
, 2005
"... This paper introduces a three-dimensional (3-D) polarized radiative transfer model that has been developed to assess the influence of cirrus clouds on radiances measured by the Earth Observing System Microwave Limb Sounder (EOS-MLS) instrument. EOS-MLS is on the Aura satellite, which launched in Ju ..."
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Cited by 12 (4 self)
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This paper introduces a three-dimensional (3-D) polarized radiative transfer model that has been developed to assess the influence of cirrus clouds on radiances measured by the Earth Observing System Microwave Limb Sounder (EOS-MLS) instrument. EOS-MLS is on the Aura satellite, which launched in July 2004. The radiative transfer model uses a reversed Monte Carlo algorithm and has been incorporated in the Atmospheric Radiative Transfer Simulator 1.1.x software package. The model will be used to study aspects of the scattering problem that are not considered in the existing operational EOS-MLS cloudy-sky forward model, including the influence of nonspherical, oriented hydrometeors, and 3-D inhomogeneous cloud structure. This paper presents the radiative transfer algorithm and example model results, which demonstrate significant 3-D and polarization effects. Although the development of this model was motivated by the EOS-MLS mission, it is also directly applicable to ground-based and down-looking geometries.
a: Physical and Microwave Radiative Properties of Precipitating Clouds. Part II: A Parametric ID Rain-Cloud Model for Use in Microwave Radiative Transfer Simulations
- J. Appl. Met
, 2001
"... ABSTRACT Using stringent criteria pertaining to rain-cloud optical thickness and horizontal extent, 3203 multichannel microwave observations of heavy, widespread tropical precipitation over ocean were selected from 9 months of global Special Sensor Microwave Imager (SSM/I) data. These observations ..."
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Cited by 8 (0 self)
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ABSTRACT Using stringent criteria pertaining to rain-cloud optical thickness and horizontal extent, 3203 multichannel microwave observations of heavy, widespread tropical precipitation over ocean were selected from 9 months of global Special Sensor Microwave Imager (SSM/I) data. These observations subsequently were found to be associated almost exclusively with stratiform rain areas in tropical cyclones. Because of the restrictions on optical thickness and spatial extent, the mean multichannel microwave brightness temperatures and their interchannel covariances are presumed to be determined primarily by the vertical microphysical structure of the rain clouds. The distribution of the above observations in seven-dimensional channel space is characterized concisely using principal component analysis. It is found that only three independent variables are sufficient to explain 97% of the variance in the correlation matrix. This result suggests that the radiometrically important microphysical properties of these rain clouds are strongly interdependent. The most significant eigenvector of the observation correlation matrix corresponds to variable scattering at high frequencies by ice aloft. Its spectral dependence is accurately given by 1.76 , where is the microwave frequency. This empirical result constrains the effective mean sizes of ice particles responsible for observed passive microwave scattering in rain clouds and provides a plausible empirical basis for accurately predicting the magnitude of scattering effects by ice at non-SSM/I microwave frequencies. There are also qualitative indications that this mode of brightness temperature variability is poorly correlated with surface rain rate in this study sample. The empirical results presented herein are expected to be of value for the validation and improvement of microphysical assumptions and optical parameterizations in forward microwave radiative transfer models. Companion papers describe the actual retrieval of effective rain-cloud microphysical properties from the observed multichannel radiances.
A Texture-Polarization Method for Estimating Convective–Stratiform Precipitation Area Coverage from Passive Microwave Radiometer Data
, 2000
"... Observational and modeling studies have revealed the relationships between convective–stratiform rain pro-portion and the vertical distributions of vertical motion, latent heating, and moistening in mesoscale convective systems. Therefore, remote sensing techniques that can be used to quantify the a ..."
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Cited by 2 (0 self)
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Observational and modeling studies have revealed the relationships between convective–stratiform rain pro-portion and the vertical distributions of vertical motion, latent heating, and moistening in mesoscale convective systems. Therefore, remote sensing techniques that can be used to quantify the area coverage of convective or stratiform rainfall could provide useful information regarding the dynamic and thermodynamic processes in these systems. In the current study, two methods for deducing the area coverage of convective precipitation from satellite passive microwave radiometer measurements are combined to yield an improved method. If sufficient microwave scattering by ice-phase precipitation is detected, the method relies mainly on the degree of polarization in oblique-view, 85.5-GHz radiances to estimate the fraction of the radiometer footprint covered by convection. In situations where ice scattering is minimal, the method draws mostly on texture information in radiometer imagery at lower microwave frequencies to estimate the convective area fraction. Based upon observations of 10 organized convective systems over ocean and nine systems over land, in-stantaneous, 0.58-resolution estimates of convective area fraction from the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) are compared with nearly coincident estimates from the TRMM precipitation radar (PR). TMI convective area fraction estimates are low-biased relative to PR estimates, with TMI–PR
Interpretation of Polarization Features in Ground-Based Microwave Observations as Caused by Horizontally Aligned Oblate Raindrops
, 2000
"... Based on a comparison of ground-based radiometer measurements with microwave radiative transfer calcu-lations, it is shown that raindrops with an oblate shape and a preferred horizontal orientation have a significant effect on microwave polarization signals when compared with spherical particle shap ..."
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Based on a comparison of ground-based radiometer measurements with microwave radiative transfer calcu-lations, it is shown that raindrops with an oblate shape and a preferred horizontal orientation have a significant effect on microwave polarization signals when compared with spherical particle shape. Measurements with a dual-polarized 19-GHz radiometer reveal a polarization difference of as much as 218 K in the downwelling microwave radiation at 308 elevation angle. Averaging all rain observations within 19 months leads to a signal of 26 K. Model calculations covering roughly the same range of weather conditions as that inferred from the meteorological data recorded with the radiometer measurements were carried out with spherical raindrop shape and an oblate particle shape with a fixed horizontal alignment. From the model results, positive polarization difference is expected for spherical particles. This signal was never observed in the recorded data. For oblate drops, the averaged model results lead to a polarization difference of 28 K, which is in reasonable agreement with the long-term averaged observations. Case studies that compare isolated rain events usually lead to a better match of model and observations. However, there are some major discrepancies in some cases. Possible reasons for the remaining differences are the short-term variations in the cloud microphysics for which the model does not correctly account, such as variations in the melting layer, drop oscillations, or variations in the drop size
CORRECTING FOR PRECIPITATION EFFECTS IN SATELLITE-BASED PASSIVE MICROWAVE TROPICAL CYCLONE INTENSITY ESTIMATES
, 2005
"... Public reporting burden for this collection of Information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments ..."
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Public reporting burden for this collection of Information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this
CORRECTING FOR PRECIPITATION EFFECTS IN SATELLITE-BASED PASSIVE MICROWAVE TROPICAL CYCLONE INTENSITY ESTIMATES
, 2005
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HARRIS AND FOUFOULA-GEORGIOU: CLOUD MODEL DOWNSCALING
"... Subgrid variability and stochastic downscaling of modeled clouds: Effects on radiative transfer computations for rainfall retrieval ..."
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Subgrid variability and stochastic downscaling of modeled clouds: Effects on radiative transfer computations for rainfall retrieval
TRANSACTIONS ON GEOPHYSICS AND REMOTE SENSING 1 A 3D Polarized Reversed Monte Carlo Radiative Transfer Model for mm and sub-mm Passive Remote Sensing in Cloudy Atmospheres
"... Abstract This paper introduces a 3D polarized radiative transfer model that has been developed to assess the inuence of cirrus clouds on radiances measured by the EOS-MLS instrument. EOS-MLS is on the Aura satellite, which is due for launch in June 2004. The radiative transfer model uses a reversed ..."
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Abstract This paper introduces a 3D polarized radiative transfer model that has been developed to assess the inuence of cirrus clouds on radiances measured by the EOS-MLS instrument. EOS-MLS is on the Aura satellite, which is due for launch in June 2004. The radiative transfer model uses a reversed Monte Carlo algorithm and has been incorporated in the ARTS 1.1.x software package. The model will be used to study aspects of the scattering problem that are not considered in the existing operational EOS-MLS cloudy-sky forward model, including the inuence of non-spherical, oriented hydrometeors and 3D inhomogeneous cloud structure. This paper presents the radiative transfer algorithm and example model results, which demonstrate signicant 3D and polarization effects. Although the development of this model was motivated by the EOS-MLS mission, it is also directly applicable to ground-based and down-looking geometries. I.
