Satellite-based Time-Series of Sea Surface Salinity designed for Ocean and Climate Studies

Le résumé fourni par la source

Sea Surface Salinity (SSS) is an Essential Ocean and Climate Variable, which is increasingly used as part of climate studies. SSS measurements are available from three satellite missions, SMOS, Aquarius and SMAP, each with very different instrument features leading to specific measurement characteristics. The Climate Change Initiative Salinity project (CCI+SSS) aims to produce SSS Climate Data Record (CDR) to include satellite measurements, based on well-established user needs. To generate a homogeneous CDR, instrumental differences are carefully controlled by analysing SSS discrepancies, then adjusted based on in-depth analysis of the measurements themselves together with independent reference data. However, no spatial smoothing or temporal relaxation to reference data is applied in order to maintain the variability contained in the original data set. SSS CCI fields are well suited for monitoring weekly to interannual variability from the ocean basin scale to the large mesoscale. Thus, they depict that over the 2010-2019 decade, seasonal have varied greatly from year to year, sometimes by more than +/-0.4 over large regions. When monthly SSS CCI are compared with in situ Argo salinities, the robust standard deviation of their difference, at global scale, is 0.15, while r 2 is 0.97. This high level of performance highlights the benefit of the SSS CCI merging approach compared to individual satellite SSS fields alone. The correlation with independent ship SSS (r 2 >0.9) further highlights the excellent performance of the data set. SSS CCI data are freely available and will be updated and extended in the future as more satellite data become available.

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