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26 September 2007 RADARSAT ScanSAR wind retrieval under hurricane conditions
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RADARSAT-1 ScanSAR SWA images of Hurricane Katrina are used to retrieve the surface wind vectors over the ocean. Due to the inadequate spatial resolution of the ScanSAR SWA images, the spectrum method cannot be implemented to estimate the wind direction. Instead, collocated H*wind wind directions are used as wind direction estimates. The wind speed is derived from the σ° by inversion of a C-band HH-polarization Geophysical Model Function (GMF), which is derived from C-band VV-polarization GMF using a polarization ratio model. Because existing polarization models don't fit the ScanSAR SWA data well, a recalibration model is proposed to "recalibrate" the ScanSAR SWA images. The coefficients of the recalibration model are "tuned" using collocated H*wind surface wind fields. To validate the SAR-retrieved wind speed, the mean and the RMS difference between SAR-retrieved and H*wind wind speed estimates are calculated. The mean of difference is small and the RMS for wind speed less than 25 m/s is below 4 m/s, suggesting that the high resolution wind retrieval algorithm can work under hurricane conditions. Except for the influence from rain, the largest errors occur at high wind speed (over 25 m/s), which is mainly due to the saturation of the C-band GMF CMOD5.
© (2007) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Congling Nie and David G. Long "RADARSAT ScanSAR wind retrieval under hurricane conditions", Proc. SPIE 6677, Earth Observing Systems XII, 66770K (26 September 2007);


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