Relationship Between Indian-Summer Monsoon Rainfall And Position Of Pacific-Ocean Warm Pool

Abstract

A new oceanic parameter linked to Indian summer monsoon rainfall (ISMR) has been identified. A large area of the Pacific Ocean having sea surface temperature > 29ᵒ C in satellite derived multi-channel sea surface temperature (SST) or blended SST, called Pacific Ocean warm pool (POWP) is the new parameter. Statistical relationship between monthly anomalies of the position of POWP and monthly ISMR anomalies has been investigated. A significant negative relationship is observed between the parameters. The linear correlation coefficient obtained between anomalies of the zonal positions of POWP and ISMR, for 22 pairs of observations between 1983 and 1988, is -0.79 and significant at 0.1% level. The non-linear correlation coefficient, corresponding to the second degree equation fitted to the data, is -0.80. The high correlation is due to dependence of the atmospheric circulation pattern in the tropics, especially over India on the position of POWP. Probable sequence of related events is explained and ways of utilising the relationship for forecasting monthly rainfall over India are discussed.