RESPONSE OF TROPICAL ATMOSPHERIC CIRCULATION IN JULY—AUGUST TO TWO EL NINO TYPES

E. M. Volodin

From observational data for 48 years, it is shown that in the case of the negative correlation between sea surface temperature (SST) in the El Nino region and all-India summer rainfall, there is a significant SST anomaly in the central and eastern Pacific. In the years with no such correlation, the SST anomaly is observed in the eastern equatorial Pacific only. The response of tropical atmo¬spheric circulation to the tropical Pacific SST anomalies in July—August is studied using observational data and the atmospheric general circulation model. Numerical experiments have shown that in the case of a strong SST anomaly in the central and eastern Pacific there is a local response and a remote response of a weakening of the easterlies in the upper tropical troposphere. In the case of a strong SST anomaly in the eastern Pacific only, there is a local response of atmospheric circulation. The same conclusion is valid for the observational data.