The Spatial Asymmetry of the South China Sea Thermocline Depth in Response to El Niño Events

In order to better study the impact of El Niño events on the thermocline depth (TD) in the South China Sea (SCS), this paper analyzes the spatial characteristics of thermocline depth in response to the El Niño events from 1958 to 2010 over the SCS based on reanalysis data. Results show that during the El Niño events the spatial distribution asymmetry of the thermocline depth anomaly in the SCS is mainly of north-south asymmetry. Compared with the Central-Pacific El Niño events, the thermocline depth in the SCS has stronger response to the Eastern-Pacific El Niño events. Western North Pacific anomalous anticyclone (WNPAC) is an important bridge connecting the El Niño phenomenon and the SCS wind field anomaly. The SCS wind field anomaly exhibits north-south asymmetry caused by the WNPAC during El Niño events, and further leads to the north-south asymmetry in the thermocline depth anomaly. The differences in WNPAC and wind field anomaly in the SCS are the key reasons for the different response of thermocline depth to different types of El Niño events.