Performance Evaluation of WRF Model in Simulating Extreme Rainfall Events Over Bhubaneswar Urban Region of East Coast of India

Abstract

The urbanization and frequency of extreme rainfall events (EREs) have considerably increased over the recent decade in several cities in India. Forecasting of these EREs remains a significant challenge not only in urban environments but also across diverse geographical regions. However, there is a particularly pressing need for improved rainfall forecasts in urban areas where the impacts of cities and human activities are profound. Using the Weather Research and Forecasting (WRF) model, a series of sensitivity experiments have been carried out by changing the various parameterization schemes to establish an improved model configuration for predicting EREs across the city of Bhubaneswar, Odisha- one of the most vulnerable cities to heavy rainfall in the recent decades. The study examines the influence of the urban heat island (UHI) effect on EREs, focusing on two specific EREs that occurred over Bhubaneswar and neighboring regions during the summer and post-monsoon season on July 19–21, 2018, and October 19–21, 2017. A total of thirty-two combinations of various cumulus, microphysics, and land surface sensitivity experiments are carried out for each ERE (a total of 64 for the two events). The results show that the combinations of Noah +  + Nocumulus and Noah-MP + Thompson + Kain-Fritsch are the most effective in capturing the spatial and temporal patterns of EREs with a root mean square error of 33.9 and 36.2 mm, respectively. In addition, the study successfully reproduced vertical integrated specific humidity. Moreover, it has been observed that the UHI effect reduces rainfall intensity by 4% within urban areas during extreme rainfall events.