Tropical cyclone predictions over the Bay of Bengal using the high-resolution Advanced Research Weather Research and Forecasting (ARW) model

The performance of the high-resolution Advanced Research Weather Research and Forecasting (ARW) model for tropical cyclone prediction over the Bay of Bengal region of the northern Indian Ocean is assessed through study of 21 cyclone systems. Error metrics in the predicted fields of maximum sustained winds (MSW), central sea-level pressure (CSLP) and the vector track position are computed by comparison with corresponding tropical cyclone estimations from the India Meteorological Department (IMD). From 65 sensitivity experiments for five severe cyclones the combination of Kain-Fritsch (KF) convection, Yonsei University (YSU) planetary boundary layer (PBL), LIN explicit microphysics and NOAH land surface schemes are found to provide the best simulations for intensity and track prediction. It has been found that the KF convection scheme gives higher convective warming with stronger vertical motions relative to other tested cumulus schemes and that the YSU scheme simulates more realistic winds in the inflow region than other tested PBL schemes. Results of simulations with the best physics for all 21 cyclones reveal that the model had a tendency to overestimate the intensity, with mean errors ranging from -2 to 15 hPa for CSLP, 1 to 22 m s(-1) for MSW corresponding to 24 to 72 h predictions. The mean vector landfall position errors are found to be 122 km at 12 h, 170 km at 24 h, 244 km at 48 h and 250 km at 72 h, and 67% of the landfall errors are less than 135 km, indicating fairly good forecasts. Further, the predictions are found to be best for northward moving cyclones followed by northwestward, westward and northeastward moving cyclones.