Modeling L-Band Reflection and Emission From Seawater, Foam, and Whitecaps Using the Finite-Difference Time-Domain Method

Reflection and emission from flat and rough seas with embedded whitecaps (WCs) are investigated at L-band using a custom finite-difference time-domain electromagnetic model. The model is applied to multiple layers, with vertically inhomogeneous dielectric profiles representing foam and spray overlying a homogeneous seawater layer. The foam and spray layers are adapted from an L-band radiative transfer model, and the rough sea surface is a statistical realization of the Kudryavtsev wave spectrum model. The 1-D and 2-D model versions are validated for a flat sea with optional foam cover, and the emissivity effects of WCs embedded in flat and rough seas are investigated. An overlying spray layer is found to markedly reduce WC detectability. Possible applications are the stochastic simulation of WC cover and its effect on emissivity at various wind speeds, and the effects of wave and WC shape on emissivity.