Dependency of NRCS of Ocean Surface on Wind Direction Using an Airborne Dual-Frequency Polarimetric SAR Observation

The normalized radar cross section (NRCS) of ocean surface is measured from three directions of illumination by an air-borne dual-frequency synthetic aperture radar (SAR) in the L- and X-bands, and the dependency of the NRCS and the polarization ratio on the relative wind direction is analyzed. In the X-band, the dependencies of the NRCSs in the parallel polarizations are different each other. The NRCS in the X-band HH polarization has difference between the up-and down-wind conditions, though that in the VV polarization the NRCSs for the up- and down-wind conditions are almost same. The dependency of the NRCS in the L-band is smaller than that of the X-band. The polarization ratio in the X-band shows the dependency on the wind direction with difference between the up- and down-wind conditions, though that in the L-band is not apparent. The results suggests the possibility of ocean wind measurement by the polarimetric SAR in the X-band.