Impact of solar radiation on sea surface salinity remote sensing by spaceborne synthetic aperture imaging radiometers

Since the Sun is a very bright radiation source at L-band, reception of direct and Earth-reflected solar radiations by downward-looking radiometers raises a significant challenge for the remote sensing of ocean surface salinity. For a given spaceborne mission concept, the impact of the Sun radiations depends on the sensor antenna properties, the location of the Sun relative to both the spacecraft and the reflecting surface, as well as on the surface scattering properties of the observed Earth scene. Effects on interferometric data, (i.e. visibilities), provided by Synthetic Aperture Imaging Radiometers (SAIR) need to be accounted for; the affected area, determined through both geometrical and geophysical considerations, have to be either masked or flagged, or submitted to specific correction procedures, for correct sea surface salinity retrieval. Focusing on the future ESA Soil Moisture and Ocean Salinity (SMOS) space mission, we provide quantitative and qualitative estimates for measurements contamination by Sun as expected for the period 2007-2010, and we derive methods that can serve to develop a consistent correction strategy