Assessing Sea Surface Salinity Derived by Aquarius in the Indian Ocean

The letter has been motivated by the need to validate the sea surface salinity (SSS) derived by Aquarius mission in the Indian Ocean. Validation has been performed on daily level-3 SSS data obtained by Aquarius in the Indian Ocean region during 2011-12. The in situ data sets available from Argo floats have been utilized for this purpose. The coefficient of determination between SSS and reference measurements is 0.84 and root mean square difference (RMSD) is about 0.45 psu. Spatial distributions of average salinity and variability of salinity have been found to agree reasonably well with the known features of SSS in this ocean basin. Under the assumption that the autocorrelation of SSS anomaly has anisotropic Gaussian characteristics, we also evaluated the space-time decorrelation scales of this anomaly, with the usual definition that decorrelation scales are the e-folding scales of SSS anomalies.