Eddy induced SST variation and heat transport in the western North Pacific Ocean

Abstract

Vigorous mesoscale eddies and significant sea surface temperature (SST) variations are found in the northern edge of the Pacific warm pool that features large SST gradient. However, the relations between SST gradient, eddies, and SST variations in this region remain unexplored. In this study, by combining multi-altimeter sea surface height (SSH), satellite microwave SST observations and a mesoscale eddy dataset, we investigated the two-dimensional structures of SSTa (SST anomalies) in two subareas, which have different eddy characteristics and can be discriminated in the intensity of background SST gradient. The eddy characteristics of this region, focusing on their concentration to 21°N, are also described. We found that eddies can result in two distinct patterns of eddy-induced SST anomalies, with two different horizontal processes respectively. One is a monopole pattern that is caused by elevation/depression of the isopycnals, and another is a dipole pattern caused by eddy’s rotation and stirring of the background SST field. In addition, contributions of both parts to the total SSTa and the SSTa variations were evaluated. The intensity of surrounding SST gradient plays an important role in shaping the SSTa structure: when SST gradient is larger, the eddy-associated SSTa pattern organizes more dipole. The distinct annual cycle in two components of SSTa is associated with the seasonal modulation of the warm pool’s horizontal structure.