A Study on Microwave Emissivity from Wind-Induced Sea Foam

Abstract

Wind is a major factor in the formation of sea surface foam. Foam layer parameters, such as thickness and coverage are functions of wind speed. Microwave emissivity of sea surface is sensitive to thickness of its foam cover. Foam thickness plays a vital role in emissivity from sea surface with foam cover. The average thickness of foam layer is can be estimated from sea surface wind speed. In this study, the foam layer emissivity is simulated using the incoherent multiple scattering model at different wind speeds and observation frequencies. Model predictions show that emissivities at different frequencies are sensitive to average foam thickness (and wind speed) at different ranges. Model Comparisons with AMSR2 measurements show good agreement on how foam emissivity varies with wind speed; they also show better correlation for V-polarized emissivity at 36.5GHz and 6.9GHz at wind speed of 5 m/s to 30 m/s.