The Relation between Indian Monsoon Rainfall, the Southern Oscillation, and Hemispheric Air and Sea Temperature: 1884–1984

Abstract

Correlations between the June-September Indian monsoon rainfall and Santiago minus Darwin pressure, Tahiti minus Darwin pressure, and Wright's Southern Oscillation index, as well as the individual station pressure deviations themselves, show that the monsoon rainfall anticipates the Southern Oscillation Indices and the individual pressure deviations with the exception of the pressure at Santiago. Monsoon rainfall is also negatively correlated with sea surface temperatures in the eastern equatorial Pacific one to two seasons later. The correlations suggest that above average monsoon rainfall is associated with below average Southern Hemisphere temperatures two to three seasons later, whereas above average Northern Hemisphere winter temperatures—particularly continental temperatures—anticipate above average rainfall. The correlations with hemispheric temperatures are significant only since about 1947, however. A strong negative correlation (−0.64) between the seasonal change in Darwin's pressure deviation from December-February to March-May prior to the monsoon, and monsoon rainfall is found in the period 1947–84, but only weakly in the period before 1947.