IMPACTS OF ENSO AND IOD ON THE INDIAN RAINFALL

Abstract

Water is vital to life. India is an agriculture based economy more than 50 percent of the population dependents on the agriculture. More than 60 percent of agricultural land is rain fed. The main source of water is summer monsoon rainfall as 78 percent of total annual rainfall occurs in the monsoon period. Though the summer monsoon rainfall varies on inter annual basis. The variation in the summer monsoon is modulated by two phenomena El Nino Southern Oscillation (ENSO) and recently discovered Indian Ocean Dipole (IOD). We used lITM rainfall data, Aphrodite's gridded precipitation data and TRMM rainfall data. To study the impact of ENSO and IOD on the Indian rainfall. Temporal as well as spatial variation of rainfall due to ENSO and IOD is studied. Their Impact on extreme rain events, relation of intensity is also studied. The results suggest that ENSO greatly influenced the Indian Summer * Monsoon Rainfall in the last century. ENSO can attribute nearly 20 percent of the variance in the ISMR. The relation is changing now, influence of ENSO is getting weaker while that of IOD is increasing since past two decades. The impact of ENSO as well as IOD varies spatially throughout the country. Some parts have more impact other have lesser. Their impact on EREs is also varies spatially. There is no profound impact is observed on the intensity of rainfall. Hence in the agricultural planning and in management of water resources. The knowledge of ISMR relation with ENSO and IOD can very useful to water managers and for well-being of 1.2 billion people of the country.