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BACKSCATTERING  FROM  SEA  SURFACE  WITH  PRECIPITATION. Saibun Tjuatja, Li Jiamei , Dong Xiaolong Wave Scattering Research Center The University of Texas at Arlington & Chinese Academy of Sciences Center for Space Science and Applied Research Microwave Remote Sensing Laboratory July 25, 2011. - PowerPoint PPT Presentation

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An Approach for Modeling Microwave Scattering from Sea Surface with Precipitation

BACKSCATTERING FROM SEA SURFACE WITH PRECIPITATIONSaibun Tjuatja, Li Jiamei, Dong Xiaolong

Wave Scattering Research CenterThe University of Texas at Arlington&Chinese Academy of Sciences Center for Space Science and Applied ResearchMicrowave Remote Sensing Laboratory

July 25, 2011This work is supported in parts by the Chinese Academy of Sciences Visiting Professorships for Senior International Scientists ProgramObjectives of this studyA physics based backscattering model that accounts for the vertical profile of the rain columnQuantitative link between geophysical parameters and backscattering measurements

94 GHz Radar Reflectivity and Doppler Velocity from CRS measurements (Li et al., 2004)Physics Based Forward Modeling:Microwave scattering from sea surface with precipitationPhysical ParametersModel ParametersPhysical StructureModel StructureA Scattering Model for an Inhomogeneous Layer with Vertical Profile

Rain Layer ParametersVertical profilemodeled with 12 sublayersRain rate:10.48 mm/h and 22.80 mm/hDrop size distribution:average drop sizevolume fractionDrop shape: spherical

Vertical Profile (Average Drop Size) of Rain Columnprofile A: R = 10.48 mm h-1 Volume fraction: 0.7500E-05

profile B: R = 22.80 mm h-1 Volume fraction: 0.8000E-05

Rain Ratewhere

Drop Size Distribution Gamma distribution:

Volume fraction of rain drops:

Other Model ParametersSea surface roughness (IEM model)

Rain drop relative permittivity (at 13.6 GHz):

Model AnalysesEffects of precipitation at C- and Ku-BandEffects of rain ratesEffects of drop average drop size at constant REffects of volume fraction with a constant average drop sizeEffects of snow & melting layer

Effects of Precipitation (R=10.48mm h-1 ) at C- and Ku-Band

Effects of Rain Rate

Effects of Drop Size with Constant R

Effects of Volume Fraction with a Constant Drop Size

Vertical Profile with Snow & Melting Layer

Effects of snow & melting layer

Summary & ConclusionA scattering model for rain column above sea surface which accounts for vertical profile was developed and qualitatively validated.Model analyses show that at R=10.48 mm/h, the effects of precipitation at C-Band is negligible at small incident angles At Ku-Band, key features for differentiating backscattering from sea surface with and without precipitation include:angular trend separation between VV and HHThank you

Cloud Layer

Rain Layer

Water

An algorithm for determining the scattering coefficient from sea surface with precipitation:

1.

Determine the volume-scattering phase-matrix set for each sublayer, where , using the scattering operator (matrix-doubling) method.2.

Determine the total volume scattering phase-matrix set for the rain layer, , using where denotes scattering operation.3.

Determine the effective reflected and transmitted scattering phase matrices for the cloud-rain interface: and for Z incidence, and and for +Z incidence. Determine the effective reflected scattering phase matrix for the sea surface, .4. The total scattering phase matrix for the sea surface with precipitation is determined by

Cloud Layer

Rain Layer

Water

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