Role of El Nino/La Nina in temperature extremes over India

摘要

El Nino and La Nina are well known to be associated with significant monthly/seasonal climate anomalies at many places around the globe. Therefore, an attempt is made in this study to analyse objectively defined indices of observed temperature extremes over India, in terms of their frequencies and intensities, in relation to El Nino/La Nina events using daily station data for minimum and maximum temperature at 121 well-distributed stations for the period 1970-2003. There is a characteristic change in the El Nino southern oscillation (ENSO)-associated extremes with the onset of the summer monsoon in June; El Nino is associated with lower frequency of warm extremes during the pre-monsoon months and with higher frequency of warm extremes during the monsoon and post-monsoon season. The opposite features are seen in the case of La Nina. In addition, El Nino leads to an increase in extreme highest temperature, whereas La Nina leads to a decrease, during monsoon and post-monsoon months. Strong antecedent relationship exists between ENSO index and various seasonal extreme temperature indices over the Indian region, indicating potential for long-range prediction of 41 temperature extremes.