Enso Association With Rainfall

This study is mainly focused on Dikhow catchment which is a part Brahmaputra river basin, located between 94°28’49”E to 95°09’ 52” E longitude and 26°52’ 20”N to 26°03’ 50” N latitude. The geographical area of Dikhow catchment is about 3100 km 2 , which encompasses around 85% of Nagaland, ten percent of Assam and five percent of Arunachal Pradesh. This study is more precise to find out the relationship using between El Niño-Southern Oscillation (ENSO) and rainfall for Dikhow catchment, using statistical techniques. Monthly rainfall data of six stations of study area from 1950–2002 were acquired from the Indian Meteorological Department Pune and monthly SST anomalies of Niño of 3.4 regions (5°N to 5°S and 170°W to 120°W) during the study period (1950–2002) were downloaded from the NOAA, National Weather Service (NWS), and National Center for Environmental Prediction (NCEP), Climatic Prediction Center (CPC) ( https://www.cpc.noaa.gov/data/indices"> https://www.cpc.noaa.gov/data/indices ), to classify ENSO events. Results showed that the significant correlation was found for monsoon rainfall only while winter and summer rainfall showing insignificant correlation. Sibsagar, Tirap, and Mon stations portrayed the significant correlation between monsoon rainfall with ENSO and insignificant correlation observed between remaining three stations. Further, the probability of exceedance of long-term average monsoon precipitation was also lower during El Niño episodes than La Niña and neutral years for these stations (Sibsagar, Tirap, and Mon).