资源环境科技发展态势分析平台

The response of the Arctic stratosphere to El Nino activity is strong but the response to La Nina activity is relatively weak. The asymmetric responses of Arctic stratosphere to El Nino and La Nina events are thought to be caused by asymmetric El Nino-Southern Oscillation (ENSO) teleconnections. Here, we suggest that the background sea surface temperature (SST) over cold tongue of tropical eastern Pacific may be an important contributor to the asymmetric ENSO teleconnections. The atmosphere is very sensitive to tropical SST variations in the range of 26 degrees C-30 degrees C. During El Nino events, the background SST over cold tongue plus El Nino SST anomalies typically falls into the range. Under these conditions, the atmospheric response to El Nino SST anomalies is strong. During La Nina events, the background SST plus La Nina SST anomalies is typically below the range, which leads to a weak response of the atmosphere to SST anomalies. The proposed mechanism is well supported by simulations.