Sea Surface Salinity Observations With SMOS Satellite: a New Tool to Better Monitor the Marine Branch of the Water Cycle
Reul, Nicolas1; Fournier, Severine1; Boutin, Jaqueline2; Hernandez, Olga2; Maes, christophe3; Chapron, bertrand1; Alory, Gael4; Quilfen, yves1; Tenerelli, Joseph5

The ocean is the primary return conduit for water transported by the atmosphere. It is the dominant element of the global water cycle, and clearly one of the most important components of the climate system, with an heat capacity 1100 times larger as compared to the atmosphere. Two new satellite sensors, the ESA Soil Moisture and Ocean Salinity (SMOS) and the NASA Aquarius SAC-D missions are now providing the first space borne measurements of the sea surface salinity (SSS). In this presentation, we will review how the preliminary SSS products derived from the SMOS sensor over the first three years of operation can readily help to better characterize some of the key processes of the marine branch of the global hydrological cycle. We illustrate the new monitoring capabilities for some of the world largest fresh pools of the tropical oceans. In particular, we show how SMOS SSS traces the freshwater signals from the Amazon-Orinoco and Congo river plumes in the offshore ocean. Second, we review precipitation signatures in the SMOS SSS signal detected in the Tropical oceans from intra-seasonal to interannual time scales. Synergetic analyses of these new surface salinity data sets with sea surface temperature, dynamical height and currents from altimetry, surface wind, ocean color, in situ observations and rain fall estimates is shown to help clarifying the freshwater budget in these key oceanic tropical areas. Finally, new sea surface salinity (SSS) observations from the SMOS and Aquarius/SAC-D missions help elucidate the ocean response to tropical cyclones. As now under scrutiny, the role of the salinity-induced upper ocean barrier layer is more explicitly linked to modulate the expected SST cooling and the enthalpy flux from the ocean to the atmosphere.