Seasonal variations of the relationship between some ENSO parameters and Indian rainfall

Canonical correlation analysis is used to examine the seasonal relationship between ENSO and Indian rainfall by analysing their 12 monthly values for an 80-year period. Three ENSO indices are considered. These ENSO indices are the Darwin surface pressure, the sea-surface temperature of the central and eastern equatorial Pacific, and rainfall of central equatorial Pacific islands (hereafter denoted as DSP, SST, and RAIN respectively). The ENSO indices are also analysed for relationships between themselves. The analysis reveals that the seasonal variations of these ENSO indices are highly intercoupled with no lag. These indices show the minimum association during April and the maximum after the monsoon season. Further, the seasonal variation of the Indian rainfall is found to be better associated with the seasonal variations of SST as compared with that of DSP or RAIN. This association is at its strongest during the period August-October. An apparent reversal in the relationship between ENSO and Indian rainfall is also observed from summer to winter. The warm ENSO years are associated with weak summer monsoon rainfall and at the same time high winter monsoon rainfall