Determination of sea surface salinity and wind speed by L-band microwave radiometry from a fixed platform

In May 1999, the European Space Agency (ESA) selected SMOS (Soil Moisture and Ocean Salinity) as an Earth Explorer Opportunity mission. One of its goals is the generation of global sea surface salinity (SSS) maps. The satellite sensor is an L-band interferometric radiometer with full-polarimetric capability called MIRAS. The retrieval of SSS from microwave measurements is based on the fact that the brightness temperature (T-B) of seawater is a function of the dielectric constant, temperature and sea surface state (roughness, foam...). The sensitivity of T-B to SSS is maximum at L-band, but it is necessary to quantify the other effects to have reliable SSS retrieval. In order to improve the present understanding of these effects on T-B , ESA sponsored the Wind and Salinity Experiment (WISE) 2000 and 2001 field campaigns. These experimental results are of great importance for the development of sea surface emissivity models that will be used in the future SMOS SSS retrieval algorithms. This paper presents the influence of the emissivity models on the derived SSS from the data obtained in both campaigns. It also presents the impact on the retrieved SSS of using in situ measured or satellite derived wind information, or even simultaneously estimating the wind speed from the measured multi-angular T-B.