Sea surface salinity can be measured by microwave radiometry at L-band (1400-1427 MHz). This frequency is a compromise between sensitivity to the salinity, small atmospheric perturbation, and reasonable pixel resolution. The description of the ocean emission depends on two main factors: (1) the sea water permittivity, which is a function of salinity, temperature, and frequency, and (2) the sea surface state, which depends on the wind-induced wave spectrum, swell, and rain-induced roughness spectrum, and by the foam coverage and its emissivity. This study presents a simplified two-layer emission model for foam-covered water and the results of a controlled experiment to measure the foam emissivity as a function of salinity, foam thickness, incidence angle, and polarization. Experimental results are presented, and then compared to the two-layer foam emission model with the measured foam parameters used as input model parameters. At 37 psu salt water the foam-induced emissivity increase is /spl sim/0.007 per millimeter of foam thickness (extrapolated to nadir), increasing with increasing incidence angles at vertical polarization, and decreasing with increasing incidence angles at horizontal polarization.
['Adriano Camps', 'Mercè Vall-Llossera', 'Ramon Villarino', 'Nicolas Reul', 'Bertrand Chapron', 'Ignasi Corbella', 'Nuria Duffo', 'Francesc Torres', 'Jorge José Miranda', 'Roberto Sabia', 'Alessandra Monerris', 'Rubén Paredes Rodríguez']
The emissivity of foam-covered water surface at L-band: theoretical modeling and experimental results from the FROG 2003 field experiment