SMOS+ Med: Sea Surface Salinity in the Mediterranean

Ocean salinity reflects precipitation and evaporation rates, river runoff and ice formation and melting. It is an essential variable for the Earth’s climate, because it influences ocean circulation, convection and mixing, through its effect on water density, playing an important role in the global heat exchange between ocean and atmosphere (Lagerloef and Font, 2010), a mechanism that regulates the climate. Through its role in ocean circulation, salinity also impacts primary productivity, making nutrients accessible or not to the food web, having an influence in e.g. fisheries. Salinity also influences, through the thermohaline circulation, the rate of atmospheric CO 2 uptake.This project aims at calculating a sea surface salinity (SSS) field over the north Atlantic Ocean and the Mediterranean Sea for the past 6 years, using a combination of techniques developed by the partners of the project, GEHR (Belgium) and BEC (Spain). This approach combined a debiased non-Bayesian retrieval of the SSS, the use of DINEOF (Data Interpolating Empirical Orthogonal Functions) to correct for systematic errors, and multifractal fusion to obtain a L4 dataset.The resulting dataset has been compared to in situ data, demonstrating that the new methodology reduces by half the error with respect to previous estimates of SSS in the Mediterranean Sea. The dataset is available for download at http://bec.icm.csic.es/thredds/BECEXPMED.html