Impacts of different cumulus physics over south Asia region with case study tropical cyclone Viyaru

Abstract

Tropical Cyclone Viyaru, formerly known as Cyclonic Storm Mahasen was a rapidly intensifying, category 01B storm that made landfall in Chittagong, Bangladesh on the 16th of May, 2013. In this study, the sensitivity of numerical simulations of tropical cyclone to cumulus physics parametrization is carried out with a view to determine the best cumulus physics option for prediction of the cyclones track, timing, and central pressure evolution in the Bay of Bengal. For this purpose, the tropical cyclone Viyaru has been simulated by WRF ARW in a nested domain with NCEP Global Final Analysis(FNL) data as initial and boundary conditions. The model domain consists of one parent domain and one nested domain. The resolution of the parent domain is 36 km while the nested domain has a resolution of 12 km. Five numerical simulations have been done with the same micro-physics scheme (WSM3), planetary boundary layer scheme,NOAH land surface scheme but different Cumulus Parametrization scheme. Four cumulus Parametrization schemes are KF, BMJ, GF and Tiedtke and one simulation was done without any cumulus physics scheme. The results of model simulations are compared with corresponding analysis or observation data. For best result data provided by Joint Typhoon Warning Center and NASA tropical cyclone center was used as observed for comparison. After the study it was found that tracks, intensity, wind speed, precipitation, and central pressure of the cyclone have sensitive result with different cumulus physics schemes.