The Performance Evolution of Tropical Cyclone Rainfall using WRF model and TRMM Over North Indian Ocean

Developing a tropical cyclone (TC) rainfall climatology and understanding its uncertainties using the numerical models and with the measurements are growing interest in the detection of hydrological and climate extremes in the worldwide. Despite their impacts, research focus on TC heavy rainfall has paid limited attention and a major challenge for the forecast community. The North Indian Ocean (NIO) including Arabian Sea (AS) and Bay of Bengal (BoB) is sensitive to the TC rainfall due to its large coastal habitats. The present study underscored the need and addressed the uncertainties and its governing factors responsible for the accurate prediction of TC rainfall using the Weather Research and Forecasting (WRF) model. The Contiguous Rain Area (CRA) method is adopted for better understanding and to assess the rainfall forecast errors in the model against the observations. Simultaneously, the study also developed the TC rainfall database based on 2374 samples of 71 TCs using the Tropical Rainfall Measuring Mission (TRMM-3B42) rain estimates during 1999-2017. The rainfall axisymmetric analysis shows that AS and BoB TCs produces heavy rainfall (~7-8 mm h^-1) and extremely heavy rainfall (~9-10 mm h^-1) in the storm inner-core region (0-100 km). The left-forward sector receives the maximum rainfall for any TC intensity category over the NIO region. The CRA analysis revealed that the major contributor in the TC rainfall forecast error is mainly due to the pattern error, followed by volume, displacement, and rotation error. The study emphasizes the importance of TC rainfall prediction and further helpful in the evaluation of the performance of the numerical models.