1. BACKSCATTERING FROM SEA SURFACE WITH PRECIPITATION Saibun 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, 2011 This work is supported in parts by the Chinese Academy of Sciences Visiting Professorships for Senior International Scientists Program

2. Objectives of this study A physics based backscattering model that accounts for the vertical profile of the rain column Quantitative link between geophysical parameters and backscattering measurements

3. 94 GHz Radar Reflectivity and Doppler Velocity from CRS measurements (Li et al., 2004)

4. Physics Based Forward Modeling:Microwave scattering from sea surface with precipitation Physical Parameters Model Parameters Physical Structure Model Structure

5. A Scattering Model for an Inhomogeneous Layer with Vertical Profile

6. Rain Layer Parameters Vertical profile modeled with 12 sublayers Rain rate: 10.48 mm/h and 22.80 mm/h Drop size distribution: average drop size volume fraction Drop shape: spherical

7. Vertical Profile (Average Drop Size) of Rain Column profile 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

8. Rain Rate where

9. Drop Size Distribution Gamma distribution: Volume fraction of rain drops:

10. Other Model Parameters Sea surface roughness (IEM model) Rain drop relative permittivity (at 13.6 GHz):

11. Model Analyses Effects of precipitation at C- and Ku-Band Effects of rain rates Effects of drop average drop size at constant R Effects of volume fraction with a constant average drop size Effects of snow & melting layer

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

13. Effects of Rain Rate

14. Effects of Drop Size with Constant R

15. Effects of Volume Fraction with a Constant Drop Size

16. Vertical Profile with Snow & Melting Layer

17. Effects of snow & melting layer

18. Summary & Conclusion A 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 HH

19. Thank you