Role of Mid-Level Vortex in the Genesis of Tropical Cyclone over the North Indian Ocean Using WRF Model

The formation of a tropical cyclone (TC) involves complex dynamic and thermodynamic processes. Understanding the role of mid-level vortices in the genesis of TCs over the NIO is crucial for improving TC forecasting. This study aims to enhance the field of meteorology by providing insights into these genesis processes. We utilized the National Centre for Environmental Prediction (NCEP) FNL reanalysis 1x1 degree data as input for the Weather Research and Forecasting (WRF) model version 4.0.3. The model was configured with one-way nesting between the parent and child domains. For the simulations, we employed the Kain-Fritsch (new Eta) scheme and the WRF Single-Moment 6-class graupel scheme (WSM6) as options for cumulus and microphysics. Our study identified the development of top-down vortices over the Arabian Sea (AS) and bottom-up vortices over the Bay of Bengal (BOB). We found that area-averaged mid-level relative vorticity (MRV) below 8 × 10−5 s−1 over a 6 × 6-degree area does not support the formation of TCs. Also, changes in mid-level temperature, whether increases or decreases, corresponded with the behaviour of MRV. Low-pressure systems (LPS) where vertical wind shear (VWS) did not exceed 10 ms−1 were prone to evolve into TCs. We also found that an increase in MRV, accompanied by VWS exceeding 10 ms−1, hindered the development of the mid-level vortex. Furthermore, there was an inverse relationship between geopotential height (GPH) and MRV, which favoured TC formation. The trends in MRV calculated by our model were comparable to those found by the European Centre for Medium-Range Weather Forecasts (ECMWF). Therefore, the results of this study are both valid and significant.