Polarization Dependence of L-Band Measurements Over the Ocean on Surface Wind at 23-25 Incidence Angles

Polarization dependence of L-band measurements over the ocean on surface wind is investigated for the incidence angle ranging from 23 to 25 degrees, by using the Phased-Array L-band Synthetic Aperture Radar (PALSAR) onboard the Advanced Land Observing Satellite (ALOS) and MetOp/ASCAT wind vectors. Polarization ratio (VV/HH) shows clear incidence angle and wind speed dependencies. It increases with increasing incidence angle and decreases with wind speed, ranging from 1.8 dB at 2 m/s wind to 0.5 dB at strong wind >12 m/s. These dependences are in good quantitative agreement with the Resonant Curvature Approximation (RCA) model proposed by Mouche et al. (2007). Although relative wind direction dependency of the polarization ratio is not so significant, downwind values are larger than cross- and upwind values at strong winds >12 m/s.