Impact of high resolution sea surface temperature on tropical cyclone characteristics over the Bay of Bengal using model simulations

Abstract

The Advanced Weather Research and Forecasting (WRF-ARW) model is used to carry out three simulations to examine the response of varying resolution of the sea surface temperature (SST) on tropical cyclone characteristics up to 72 hr lead time. They are named CNTL (Control, with default SST), SST1 (with SST data at 0.5� � 0.5�) and SST2 (with SST data at 0.083� � 0.083�). It is found that a lower SST (~0.2�0.4 K) within the effective radius (i.e. 2.5 times the radius of the maximum wind) of the storm leads to a weaker storm (about 7 hPa) for SST2 than for CNTL. The storm size in SST2 is about 5 km larger than in CNTL during the 24�72 forecast hours. The reduced storm size and enhanced diabatic heating in the core region facilitate a stronger storm for CNTL compared with SST1 and SST2. As a result, the central pressure of the tropical cyclone deepens further with a stronger radial pressure gradient, leading to a more rapid intensification in the CNTL than the others. A daily update of SST improved the storm track and intensity by 37% and 41% for SST2 and 9% and 20% for SST1 respectively in comparison to CNTL. The study demonstrates that SST with a higher horizontal resolution (0.083� � 0.083�) serves as a useful input parameter for the model to improve the prediction of a cyclone�s track and intensity. � 2018 Royal Meteorological Society