Comparison of SMOS and Aquarius Sea Surface Salinity and analysis of possible causes for the differences

Emmanuel P. Dinnat (1) , Jacqueline Boutin (2) , Xiaobin Yin (3) , David M. Le Vine (4) , Philippe Waldteufel (5) , Jean-Luc Vergely (6)

1 GSFC Cryospheric Sciences Laboratory
2 IPSO - Interactions et Processus au sein de la couche de Surface Océanique
3 LOCEAN - Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques
4 GSFC - NASA Goddard Space Flight Center
5 ESTER - LATMOS
6 ACRI-ST - Analytic and Computational Research, Inc. - Earth Sciences

Two ongoing space missions share the scientific objective of mapping the global Sea Surface Salinity (SSS), yet their observations show significant discrepancies. ESA's Soil Moisture and Ocean Salinity (SMOS) and NASA's Aquarius use L-band (1.4 GHz) radiometers to measure emission from the sea surface and retrieve SSS. Significant differences in SSS retrieved by both sensors are observed, with SMOS SSS being generally lower than Aquarius SSS, except for very cold waters where SMOS SSS is the highest overall. Figure 1 is an example of the difference between the SSS retrieved by SMOS and Aquarius averaged over one month and 1 degree in longitude and latitude. Differences are mostly between -1 psu and +1 psu (psu, practical salinity unit), with a significant regional and latitudinal dependence. We investigate the impact of the vicarious calibration and some components of the retrieval algorithm used by both mission on these differences.

Domaines: Physique Atmosphérique et Océanique [physics.ao-ph]; Océanographie

Emmanuel P. Dinnat, Jacqueline Boutin, Xiaobin Yin, David M. Le Vine, Philippe Waldteufel, et al.. Comparison of SMOS and Aquarius Sea Surface Salinity and analysis of possible causes for the differences. XXXIth URSI, General Assembly and Scientific Symposium (URSI GASS), Aug 2014, Beijing, China. 4 p., ⟨10.1109/URSIGASS.2014.6929701⟩. ⟨insu-01139555⟩