A Global Assessment of Eddy‐Induced Salinity Anomalies and Salt Transport by Eddy Movement

Abstract

AbstractEddy‐induced salt transport is essential in maintaining the oceanic salinity balance and global climate. However, the paucity of in situ measurements poses challenges in obtaining the spatial structure of the eddy salt transport globally. Here, we conduct a global estimation of eddy‐induced salinity anomalies and salt transport by eddy movement using 2 million historical hydrographic profile measurements and satellite‐based eddy observations spanning from 1993 to 2019. The results demonstrate rich geographic and vertical variability in the salinity anomalies induced by eddies across the global ocean. Vertical sign switches of salinity anomalies within eddies are observed in the tropical and subtropical oceans, as well as in the Kuroshio Extension region. Additionally, meridional sign switches of eddy‐induced salinity anomalies are observed in the Antarctic Circumpolar Current region. By integrating eddy occurrence probability, we refine the methodology for estimating eddy‐induced salt transport, and provide global spatial patterns of both meridional and zonal salt transport induced by eddy movement at each 2° × 2° grid. Significant salt transport by meridional eddy movement is observed in the mid‐latitude oceans, with the peak zonal‐depth integrated salt transport reaching 106 kg·s−1 in the mid‐latitudes of the southern hemisphere. Specifically, the Brazil‐Malvinas Confluence region is identified as a highly efficient pathway for meridional salt transport, with a magnitude of −1.28 × 106 kg·s−1, significantly surpassing other regions in the global ocean. These findings may provide important references for the understanding and simulation of global oceanic salinity transport.