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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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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.
Microwave brightness temperatures from tilted convective systems
- J. Appl. Meteor
, 2000
"... Aircraft and ground-based radar data from the Tropical Ocean and Global Atmosphere Coupled Ocean– Atmosphere Response Experiment show that convective systems are not always vertical. Instead, many are tilted from vertical. Satellite passive microwave radiometers observe the atmosphere at an oblique ..."
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Cited by 5 (1 self)
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Aircraft and ground-based radar data from the Tropical Ocean and Global Atmosphere Coupled Ocean– Atmosphere Response Experiment show that convective systems are not always vertical. Instead, many are tilted from vertical. Satellite passive microwave radiometers observe the atmosphere at an oblique angle. For example, the Special Sensor Microwave Imager on Defense Meteorological Satellite Program satellites and the Tropical Rainfall Measurement Mission (TRMM) Microwave Imager (TMI) on the TRMM satellite view at an incident angle of about 508. Thus, the brightness temperature measured from one direction of tilt may be different than that viewed from the opposite direction because of the different optical path. This paper presents an investigation of passive microwave brightness temperatures upwelling from tilted convective systems. To account for the effect of tilt, a 3D backward Monte Carlo radiative transfer model has been applied to a simple tilted cloud model and a dynamically evolving cloud model to derive the brightness temperature. The radiative transfer results indicate that brightness temperature varies when the viewing angle changes because of the different optical path. The tilt increases the displacements between the high 19-GHz brightness temperature (Tb19) due to liquid emission from the lower level of cloud and the low 85-GHz brightness temperature (Tb85) due to ice scattering from the upper level of cloud. As the resolution degrades, the difference of brightness
2003: Effects of underrepresented hydrometeor variability and partial beam filling on microwave brightness temperatures for rainfall retrieval
- J. Geophys. Res
"... [1] Cloud models run at 3 km resolution (typical resolution used for microwave radiative transfer applications) apart from ignoring subgrid variability (< 3 km); they also underrepresent variability of cloud particles between the scales of 3 and 15 km. In a previous study by the authors, evidence ..."
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[1] Cloud models run at 3 km resolution (typical resolution used for microwave radiative transfer applications) apart from ignoring subgrid variability (< 3 km); they also underrepresent variability of cloud particles between the scales of 3 and 15 km. In a previous study by the authors, evidence was presented that neglecting subgrid variability in modeled clouds results in considerable biases in microwave radiance computations. In this paper we present evidence that biases of the same order ( 2to 3 K for 10.7 GHz and + 4 to 5 K for 85.6 GHz) can result from underrepresented variability at scales of 3 – 15 km. In addition, this study reveals significant differences between modeled and observed precipitating fields at the ‘‘edges’ ’ of the storm (regions that border on zero precipitation) and documents the effects that these differences have on radiative transfer computations. It is found that biases due to underrepresented variability within the storm body are of the opposite direction to biases due to ‘‘edge’ ’ effects where partial beamfilling occurs over a field of view, and can counteract to give a misleading overall insignificant bias. However, having these two types of biases present in the (Tb-R) databases (formed by radiative transfer through 3 km modeled clouds) can have a significant effect on rainfall retrievals and can be the source of drastically different and
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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Enhancement of H-SAF Precipitation Retrevial Algorithm/Product over Mountainous Regions
"... Turkey is a mountainous country which includes 4 different climate sturucture and due to these special features, an enhanced Bayesian Algorithm is employed in the processing schedula of the project. This algorithm is developed based on Cloud-Radiation Database (CDR) from 14 rainy cases by Dr. Albert ..."
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Turkey is a mountainous country which includes 4 different climate sturucture and due to these special features, an enhanced Bayesian Algorithm is employed in the processing schedula of the project. This algorithm is developed based on Cloud-Radiation Database (CDR) from 14 rainy cases by Dr. Alberto MUGNAI and his team (Dr. Daniele CASELLA,
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
3D Time Dependent Stokes Vector Radiative Transfer in an Atmosphere-Ocean System Including a Stochastic Interface LONG-TERM GOALS
"... The major objective of this proposal is to calculate the 3-D, time dependent radiation field both within the ocean and in the atmosphere in the presence of a stochastically varying interface which may also be perturbed by sea foam, air bubbles, surfactants, rain, etc. This study will serve as the ge ..."
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The major objective of this proposal is to calculate the 3-D, time dependent radiation field both within the ocean and in the atmosphere in the presence of a stochastically varying interface which may also be perturbed by sea foam, air bubbles, surfactants, rain, etc. This study will serve as the genesis to the future evolution of an inversion algorithm whereby one could reconstruct images that have been distorted by the interface between the atmosphere and the ocean or the ocean itself. This study will rely heavily on both the spectral and polarimetric properties of the radiation field to deduce both the sea state and the perturbations produced on it. A second phase of this study will be to explore the asymptotic polarized light field and to determine how much information can be obtained about the IOP’s of the medium by measuring it. The third phase of this proposal will deal with the problem of improving image resolution in the ocean using some novel polarimetric techniques that we are just beginning to explore. Once these studies have been completed using a passive source, it will be rather straightforward to extend them to active sources where we can explore the use of both photo-acoustic and ultrasound-modulated optical tomography to improve image resolution. OBJECTIVES The new Navy initiative is focusing on one of the most formidable problems in radiative transfer
