Spatiotemporal variability of sea surface salinity and its covariation with freshwater flux in the Indo-Pacific Warm Pool region

Abstract

Indo-Pacific Warm Pool (IPWP) region is a key region which is sensitive to climate change. Therefore a comprehensive knowledge of the variability of sea surface salinity (SSS) for the entire IPWP region on decadal time scale is of great importance. This study mainly focuses on the spatiotemporal variability of SSS in the IPWP region, using conventional empirical orthogonal function (EOF) analysis, the lead–lag correlation analysis and long-term trend analysis. Barnett and Preisendorfer’s improved Canonical Correlation Analysis (BPCCA) is also applied to examine the covariation of SSS and freshwater flux (F) under climate change of El Niño–Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD). We found that SSS in most eastern Indian Ocean regions show obviously decreasing trends, whereas slightly increasing trends are found in most western Pacific Ocean regions. The leading two EOF modes both have a strong correlation with MEI and lead MEI by approximately 5 and 2 months, respectively. The spatial distribution of the canonical modes for SSS and F are very similar, except for slightly zonal deviation of the anomaly center between SSS and F, which can be explained by horizontal advection.