On the rise of Indian summer monsoon precipitation extremes and its correlations with long-term changes of certain anthropogenic factors and climate variability

The trends of extreme precipitation events during the Indian summer monsoon measured by two different indicators have been analyzed for the period 1901-2020, covering the entire India in 9 regions segregated by a clustering analysis based on rainfall characteristics using the Indian Meteorological Department high-resolution gridded data. The important climatological parameters correlating to such increasing trends have also been identified by performing for the first time a multivariate analysis using a nonlinear machine learning regression with 17 input variables. It is found that man-made long-term shifting of land-use and land-cover patterns, and most significantly the urbanization, play a crucial role in the prediction of the long-term trends of extreme precipitation events, particularly of the intensity of extremes. To further study this urbanization impact, a regional cloud-resolving model has been used to examine causal relation between drastic long-lasting change brought by urbanization and extreme precipitation events. The preliminary results will be presented.