A sensitivity study of WRF model microphysics and cumulus parameterization schemes for the simulation of tropical cyclones using GPM radar data

The present study focuses on determining the best combination of microphysics (MP) and cumulus parameterization (CP) schemes for the simulation of Tropical Cyclones (TCs) in the Indian subcontinent region, using the Weather Research and Forecasting (WRF) model. From the available schemes, four CP schemes, namely Kain–Fritsch, Betts–Miller–Janjic, New Simplified Arakawa–Schubert, and Grell–Devenyi, and four MP schemes, namely WSM6, Purdue Lin, Thompson, and Morrison, are selected for the sensitivity study. Seven TCs are simulated using all combinations of the chosen physics schemes. The simulated tracks and intensities are compared against the India Meteorological Department (IMD) observations. The results show that the Kain–Fritsch scheme, in combination with all MP schemes, predicts the tracks best among all the available CP schemes, but the performance of microphysics schemes is indistinguishable. A further study is conducted using the Global Precipitation Measurement (GPM) radar data to identify the best MP scheme by comparing the reflectivities. An existing radar simulator is modified to calculate the simulated reflectivities from the WRF model output corresponding to the MP schemes. The simulated reflectivities are compared against the GPM radar reflectivities, and the results show that the Thompson scheme reproduces the reflectivities closest to observations. The performance of the best set of schemes obtained from this study is compared with a random set of schemes for cyclone Bulbul, and the best set of schemes outperformed the random schemes in every aspect.