Impact Of El Niño Southern Oscillation On Monsoon Rainfall In Bhima Basin, Central India

The analysis of the effects of ENSO phenomenon on monsoon rainfall of the Bhima River basin located in Central India was investigated using 10x10 degree gridded monsoon rainfall during 1951-2003 and data of four ENSO indices (SOI, MEI, Niño 3.4 and DMI). Data of ENSO indices were divided into three seasons and only statistically significantly correlation was found between monsoon rainfall and monsoon season ENSO indices. Analysis also shows that the monsoon rainfall is positively correlated with SOI index whereas negatively correlated with all other indices. A significant change in the regional climate after 1976 has been reported in many studies. Thus, monsoon rainfall data and ENSO indices were also analyzed in two different duration i.e before and after the climate shift. Correlation between monsoon rainfall and ENSO indices increases after the climate shift year. ENSO phase wise analysis show that a strong/weak monsoon rainfall is associated with La Niña phase / El Niño phase except for the grids that are located on higher elevation where orography plays an important role in rainfall occurrences. Analysis of monsoon rainfall data of La Niña and El Niño phases describes that more rainfall is received at most of the grids during the La Niña phases which becomes higher after the climate shift year; during El Niño phase less rainfall is received which becomes lesser after the climate shift year