SENSITIVITY OF SUMMER INDIAN MONSOON TO THE 1979—1998 EL NINO FROM THE DATA OF ATMOSPHERIC GENERAL CIRCULATION MODEL OF THE INSTITUTE OF NUMERICAL MATHEMATICS, RUSSIAN ACADEMY OF SCIENCES

E. M. Volodin and V. Ya. Galin

The sensitivity of atmospheric circulation in June—August to tropical Pacific sea surface temperature (SST) variations is studied from the data of atmospheric general circulation model for 1979—1998 and reanalysis for the same years. The model simulates many features of circulation anomalies observed in the years with a positive El Nino index calculated as an expansion coefficient of the first empirical orthogonal function of the interannual SST variability in June—August within 30ºN—30ºS compared to the years with a negative index. The model shows that the Indian monsoon precipitation and the zonal wind velocity shear are negatively correlated with the El Nino index. Reduced precipitation of the Indian monsoon in the El Nino years by the model data can be explained by the excitation of atmospheric circulation anomalies over the northern midlatitudes and by their influence on Indian monsoon.

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