SMOS ocean salinity: Recent improvements and applications

The European Space Agency's Soil Moisture and Ocean Salinity (SMOS) mission, launched in November 2009, has been providing global maps of sea surface salinity (SSS) since 2010. The SMOS SSS derived with version 5 reprocessing senses realistic SSS variability at various time and space scales, although some biases remain a basin and seasonal scale. In this paper, after providing an overview of the SMOS version 5 SSS quality derived from comparisons with in situ measurements, we provide examples of the observed variability associated with tropical instability waves during 2010 and 2013. Then we show improvements expected in future SMOS level 2 reprocessing coming from a new method for retrieving Total Electron Content (TEC). We also estimate the SMOS SSS uncertainties due to uncertainties in a priori sea surface temperature (SST) and wind speed (WS), especially in the tropical Pacific Ocean where there are significant and sometimes coupled variations of SST and WS due to strong seasonal upwelling, zonal surface currents and the development of tropical instability waves.