Abstract: Sea surface salinity is an important physical quantity for studying ocean changes and its climate effects. In this study, it was compared the monthly and daily average sea surface salinity products of the SMAP satellite in 2018 with the monthly average grid products and real-time scattered salinity data of Argo respectively, its accuracy was assessed and the global sea surface salinity distribution characteristics were analyzed. The results show that the average monthly product RMSE of SMAP satellite is 0.17, BIAS is 0.11, STD is 0.17, R is 0.98, and the t-test shows a significant correlation; the average daily product RMSE of SMAP satellite is 0.28, BIAS is 0.23, STD is 0.26, and R is 0.81. Compared with the monthly average product, the accuracy of average daily product is lower. The monthly average product deviation of SMAP satellites is small in mid-latitude seas and larger in high-latitude seas; the average daily product deviation of SMAP satellites is -0.6~0.6 in the Pacific Ocean and exceeds 1.0 in the Mediterranean Sea. The global sea surface salinity is between 25.0 and 40.0, among which the Atlantic sea surface salinity is generally higher than those of the Pacific and Indian Oceans, and the global sea surface salinity has an obvious zonal distribution pattern in the latitude direction.

Key words: sea surface salinity, SMAP satellite, accuracy assessment, characteristic analysis