Reversal nature in rainfall pattern over the Indian heavy and low rainfall zones in the recent era

Abstract

This study presents the reversal nature in rainfall over heavy rainfall zone (HRZ; more than 80% of the long-period average (LPA) of the Indian summer monsoon rainfall (ISMR)) and low rainfall zone (LRZ; less than 40% of ISMR-LPA) in India. The India Meteorological Department (IMD) high-resolution (0.25˚×0.25˚) dataset is used from 1901 to 2016. The single and multiple change point detection techniques are used to nd the change in rainfall pattern over both the regions. Further, the study period is divided into two halves P1 and P2 in order to study change in rainfall pattern in the recent and past periods. In P2, rainfall pattern gets reversed and interestingly ISMR has shown an increasing trend over LRZ and a decreasing trend is noticed over HRZ and the results are statistically signi cant. The increasing/decreasing number of moderate and high intensity rainfall events are the main cause for this reversal pattern. Additionally, the number of dry days is increased over the HRZ and deceased over the LRZ. This study further con rms that 'dry becomes drier and wet becomes wetter' paradigm is not solely acceptable for India. The present study provides information about changes in dry days and ISMR variability in the context of climate change, which will be useful to agricultural risk management, water resources, drought monitoring, model developers, and policy planer on the adaptation strategies for climate change.