Polarimetric microwave radiation of wind-roughened sea surfaces

Abstract

Polarimetric radiation of wind-roughened sea surfaces is modeled using a geometr ical approach combined with the statistical method. The focus is on the geophysi cal nature of azimuthal emission signatures of sea surfaces and their relation t o the wind direction. The geometrical optics model assumes that the surfaces are composed of tilted specularly reflecting facets with the reflecting fields from each facet contributing incoherently to the total upwelling radiation, and the total radiation is calculated as a statistical averaging of contributions from individual facets. The first three Stokes parameters of sea surfaces are derived . The bright temperature azimuthal variations are characterized by the second az imuthal harmonics, which can be explained by the asymmetry of wind-driven sea su rfaces. The simulation shows that the upwelling Stokes parameters are sensitive to the wind direction and exhibits azimuthal variations up to a few Kelvin in am plitude. Theoretical interpretation of sea surface emission signatures provides the potential possibility to facilitate ocean wind vector retrieval using purely passive means.