EVALUATION OF AQUARIUS SEA SURFACE SALINITY IN THE SOUTH CHINA SEA

摘要

Sea surface salinity (SSS) is a basic property of the ocean. Its variability indicates dynamic processes such as mixing and circulation. It can be sensed from space now, using an L-band microwave sensor, Aquarius, with a resolution of 150 km and a target accuracy of 0.2psu. It is not clear yet if the SSS product from Aquarius is applicable in the marginal seas. Here in this study, we evaluated the Version 3.0 SSS product of Aquarius (v.3.0) by comparing it with concurrent in-situ measured salinity data (both underway mapping and Argo floats data) in the South China Sea. A root mean square error of 0.74 and 0.53, for underway and Argo data respectively, was obtained. This result was much lower than those obtained in the open ocean. The imperfect removal of the effect of Radio Frequency Interference (RFI) was thought to be the main reason resulting in such a high error of Aquarius SSS in this region. It was thus suggested that cautions should be kept when using SSS in quantitative studies in the South China Sea. Furthermore, the spatial distribution and seasonal variance of SSS observed by Aquarius were analyzed. It was found that they were basically consistent with those reported in historical publications. Therefore qualitative studies based on Aquarius SSS will be acceptable.