Numerical Simulation of Landfall Position and Intensity of Very Severe Cyclonic Storm ‘Vardah’ Over Bay of Bengal Using ARW Model

Numerical simulation of cyclone Vardah that crossed north Tamil Nadu coast near Chennai during 0950-1150 UTC of 12 December 2016 has been carried out using Advance Research dynamic solver of Weather Research and Forecasting Model (ARW). The model is configured with a single domain of 9 km horizontal resolution for the Bay of Bengal region. National Center for Environmental and Prediction (NCEP) GFS 3 hourly, 0.5o forecasts for initial and boundary conditions are used for performing simulations. Numerical experiments are conducted to simulate the cyclone track, wind speed and rainfall for the Tropical Cyclone (TC) Vardah. The model is integrated from 0000 UTC of 8–13 December 2016. The simulations are validated with the India Meteorological Department (IMD) observations. Results indicated that experiments starting prior to 0000 UTC of 11 December produced cyclones with higher translation speed and intensity comparative to the IMD observations. The experiment with initial conditions at 0000 UTC of 11 December produced a good simulation of cyclone parameters comparable with IMD observations. It was noticed that for every experiment the simulated track was closer to the observed for the initial 24 to 48 h, indicating that the model forecasts have high accuracy over a two day period. A deviation in the simulated track near the coast may be attributed to the use of the default USGS data set. Overall, the present case study demonstrates that the model simulation of Vardah TC was performed reasonably well by the ARW model.