Association of ENSO and IOD with Summer Monsoon Rainfall Variability over Central India

Abstract

Present study aims to unfold the trend of summer monsoon (JJAS) rainfall for past 114 years (1901–2014) over central India (16.5°N to 26.5° N, 74.5°E to 86.5°E). Further its variability over a long-term time-scale and association with ENSO (El Niño Southern Oscillation) and IOD (Indian Ocean Dipole) like events and further investigated that has more significant association. Due to a significant contribution of summer monsoon (JJAS) rainfall to annual rainfall, all investigation has been performed for summer monsoon rainfall by using high resolution (0.5°×0.5°) CRU TS3.23 gridded; monthly rainfall global data set for 114 years. Further to this, the association of ENSO and IOD has been investigated and it is observed that ENSO has a strong correlation with Indian summer monsoon rainfall as compared to IOD however for some of the monsoon seasons IOD appears to override the ENSO effect. It is noted that the ENSO cycle is significantly associated with summer monsoon rain, but the role of IOD in modulating monsoon rainfall cannot be ignored. The uncertain and irregular behavior of Indian monsoon causes a substantial impact on the economy and livelihood. Thus results may be used for the better understanding and predictability of Indian summer monsoon.

Keywords: Trend, summer monsoon, variability, ENSO, IOD, significance, correlation, rainfall index, El Nino