A review on the extreme rainfall studies in India

Climate vulnerability in the Indian region becomes a major concern due to the frequent hydro-meteorological extreme events throughout the year. The number of extreme rainfall events (ERE) associated with monsoon, thunderstorms and short-spanned local cloudbursts which are mainly ranges from a few hours to a few days, has increased in recent decades over the subcontinent. There is a need to quantify these high impact weather events and to understand the spatio-temporal dynamics and associated physical processes for the real time prediction for pro-active disaster management. This review paper highlights the various research works carried out and suggests the need of observation, modelling efforts for simulation/prediction of the EREs in the continental India. The works starting from cloudburst in the Himalayan region (Leh, Uttarakhand, Himachal Pradesh) to the heavy rainfall in Kerala, Bangalore, Mumbai, Chennai etc. as presented by earlier researchers are being reported in this compilation. The ERE intensity and frequency distribution in India are being analyzed using IMD gridded rainfall observation for 72 years. The analysis indicates the increasing trend in the intensity of daily rainfall during the ERE in the subcontinent. The current state of research in the multi-scale study of the ERE as well as their future changes based on climate model outputs are reviewed and the challenges are also reviewed. Evaluation of the capability of the state of art meso scale models like Weather Research and Forecasting (WRF) model for the simulation of such events at high resolution using the high-performance computing and the assimilation techniques are also emphasized in the recent research in this field. Along with the impact of large-scale physical processes like El Nino Southern Oscillations (ENSO), also the sensitivity of the urbanization, topography in the simulation of the convective meso-scale events is being presented and which indicated the down-scaled data are the best tool for the ERE research. This review will surely help the interdisciplinary researchers for the extreme analysis of the high impact hydro-meteorological disaster events.