Abstract
Observations indicate two favorable locations for the Tropical Convergence Zone (TCZ) during the Indian summer monsoon, one over the continent and the other over the equatorial Indian Ocean. An active spell of one TCZ coincides with a weak spell of the other TCZ. Observations also show the presence of positive sea surface temperature (SST) anomalies south of the equator over the Indian Ocean during the weak Indian summer monsoon years. The impact of such SST anomalies on the Indian summer monsoon is investigated through general circulation model ensemble experiments. The results indicate significant response over the Indian region and this response is manifested as a decrease in the monsoon precipitation and the weakening of the mean monsoon circulation. A series of identical experiments with a negative SST anomaly prescribed over the same region with the same magnitude confirm these findings.
