Future extreme precipitation changes in the South Asian Summer Monsoon Dominance Region

Abstract

This study aims to investigate the future changes in precipitation extremes across the South Asian summer monsoon domain using the latest CMIP6 global climate model (GCM) outputs under four SSP-RCPs for the near future (2031–2065) and the far future (2066–2100). The models were bias-corrected using nonparametric quantile transformation based on the smoothing spline technique. Future analysis was done in a more robust and systematic way by using seasonal-based as well as regional-based approaches. Two seasons, pre-monsoon from March to May (MAM) and monsoon from June to September (JJAS) were considered for seasonal assessment. The study area was divided into subzones based on Köppen-Geiger's climate structure for regional assessment. Five extreme precipitation indices, which describe extreme precipitation events, R95pTOT, Rx1day, Rx5day, PRCPTOT and SDII from Expert Team on Climate Change Detection and Indices (ETCCDI), were applied. The evaluation results reveal that the performance of the bias correction method differs based on the extreme precipitation index, climate zone, and season. Based on the model agreement, a negative shift in the precipitation extremes in the future will be dominant during the pre-monsoon season, particularly in the subzones of Tropical rainforest (southern regions of Sri Lanka), Tropical monsoon (Western Ghats of India, coastal regions of Myanmar, regions of Bangladesh), Tropical savannah (regions of Myanmar), and Arid steppe hot (southern regions of India, central parts of Myanmar). During monsoon season, both negative and positive shifts will prevail in the subzones, and the precipitation extremes during the far future will be more intensified than near future in most of the subzones. Additionally, the shifts will tend to decline from SSP1–2.6 to SSP5–8.5 in the near future and increment from SSP1–2.6 to SSP5–8.5 in the far future.