El Nino timings and rainfall extremes in India, southeast Asia and China

Abstract

Whereas some El Nino years are known to be associated with droughts in some parts of the globe, notably India, other El Ninos do not seem to be effective. Recently, it was observed that Unambiguous ENSOW (El Nino years, in which the Southern Oscillation Index minima and Pacific sea surface temperature maxima occurred in the middle of the calendar year) were better associated with droughts. This association was checked for rainfalls in South Asia and China. Singapore, Brunei, Indonesia and East Asia (comprising of the People's Republic of China and adjacent regions, including India) showed a good association of Unambiguous ENSOW events with droughts. Thailand, Malaysia and the whole Philippines showed some association; but the northwest Philippines showed opposite results. To find a rational for this criterion, it was checked whether such events were in any way related to the timings of the El Nino events. In general, El Ninos active during the main rainy season (June-September for all India's summer monsoon rainfall) were better associated with droughts. But some events did not fit this pattern. Also, many years not having El Ninos were associated with droughts. Thus, the El Nino relationship is not clear-cut and predictions based on the same alone are likely to go wrong more often than not, as in the case of the recent El Nino (1997).