Cooling Effect of the Stokes Drift in the South Pacific During EI Nino's Decline

The variation of sea surface temperature (SST) in the equatorial eastern Pacific plays an important role in global climate change, and waves are an important factor affecting sea surface temperature. In order to further study the impact of waves on the global climate， the relationship between Stokes drift in the South Pacific swell region and EI Nino is analyzed by using the reanalysis data of wave parameters and sea surface temperature published by ECMWF, the methods of EOF analysis, and advanced-lag correlation analysis. First a swell index and various wave characteristic values are selected to summarize the characteristics of global swell. It is concluded that the swell is more dominant in low latitudes, southern hemisphere, and the eastern boundary of the ocean. Based on this, the swell region of the South Pacific is delineated, and its role as a channel connecting the Southern Ocean and the equatorial eastern Pacific is found. Furthermore, the influence of Stokes drift in the South Pacific swell region on the SST in the equatorial eastern Pacific is studied. The results show that following the occurrence of EI Nino event, the meridional Stokes drift in the region will be strengthened, so the wave induced Stokes drift transports the high latitude cold water to low latitude sea area, thus cools the low latitude sea area and accelerates the decline of EI Nino, affecting the global climate. This paper not only provides a new idea of explaining the decline of EI Nino, but also opens up a new direction for the study of large-scale effects of waves.