Microwave Emission and Scattering from Ocean Surface Waves in the Southern Beaufort Sea

Abstract

Estimates of the relationships between geophysical variables and microwave backscatter/emission are important for the evaluation of atmosphere-ocean interaction, as well as energy, and mass transfer across this interface. We evaluate ship-based passive microwave brightness temperatures Tb at 37 and 89 GHz and active polarimetric backscatter at 5.5 GHz (C-band), as these relate to buoy-derived ocean wave parameters for distinct wave regimes in the southern Beaufort Sea. Microwave emission and backscatter are shown to be sensitive to the ocean surface physical roughness as defined by the significant wave height Hm0, compared to wind speed. The Tb shows significant correlation with Hm0, with the strongest correlation for the H-polarization channel at 37 and 89 GHz. Active co-γco and cross-γcross polarization ratios at 40° incidence angle are associated with Hm0, with the γco increase proportional to Hm0. The polarimetric coherence parameter ρVVHH at 20° also shows an inverse relationship with Hm0 because of an expected decorrelation of complex returns with greater surface roughness.