Impacts of Large-scale climatic oscillations on Indian Summer Monsoon Rainfall

Abstract:

Large-scale ocean-atmospheric phenomena or climatic oscillations have a strong influence on Indian Summer Monsoon Rainfall (ISMR). ISMR has both temporal and spatial variability that causes frequent droughts and floods in various parts of India. The variations in ISMR have significant effects on agriculture, annual water availability, power generation, and the country's economic growth. The large-scale climatic oscillations and their interaction with decadal to multi-decadal oscillation can provide significant information about floods and droughts on a regional scale. Here we examine how ISMR is varying with different oscillations like El Niño Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), Atlantic Multi-decadal Oscillation (AMO) and Equatorial Indian Ocean Oscillation (EQUINOO) in different regions of India. The goal of this study was to understand how ISMR varies spatially and temporally with individual and coupled climatic oscillations. The coupled analysis was performed to understand how interannual oscillation interacts with different phases of decadal and multidecadal oscillations. A non-parametric statistical method was used to identify and quantify the teleconnection between ISMR and global atmospheric circulations. The individual analysis shows that ENSO has a greater influence in changing the spatial pattern of ISMR than PDO/AMO. Moreover, La Niña coupled with other phases of decadal and multidecadal oscillations enhances ISMR and El Nino interact with different phases of other climatic oscillations showed below normal ISMR. The results of the coupled analysis provide the importance of the effects of climatic oscillations on ISMR and this study can be effectively used as a guideline for making better decisions on water management.