Performance Evaluation of WRF (NMM) model for selected Tropical Cyclones over Bay of Bengal and Arabian Sea

Abstract

In this paper, performance of WRF (NMM) model was evaluated for tracks of some selected cyclones over the North Indian Ocean (NIO) region. The model was run at the resolution of 27 km for forecast up to 72 hours with the use of NCEP FNL data sets as the initial and boundary conditions. The study includes total 106 sets of initial and boundary conditions for the 19 cyclone episodes which occurred during the period from 2004 to 2010. Verification is carried out against the observed best track of cyclone as reported by India Meteorological Department (IMD). The forecast track errors for the NIO were less than 150 km for 12 hours to 24 hours forecasts; errors were between 150 km -250 km for 36 hours to 48 hours forecasts and errors were between 250 - 300 km for 60 hours to 72 hours forecasts. The model shows westward bias during first 36 hours forecast and then eastward bias during 48 hours to 72 hours forecast. It shows northward bias at all forecast hours. During the post-monsoon season, model showed faster west-ward track in the first 48 hours forecast and then eastward bias in the 60 hours to 72 hours forecast. During pre-monsoon season it shows north and west ward bias in the first 36 hours forecast and in the subsequent forecast hours it shows eastward bias. For the northeast recurvature cyclones, track errors were between 100 km to 150 km for 12 hours to 24 hours forecast and in the range 200 km to 300 km for 36 hours to 48 hours forecast. The track errors were greater than 300 km for 60 km to 72 hours. For the southwest recurvature cyclones, the track errors were between 250 km to 550 km for forecast up to 72 hours. Performance of the model was better than the CLIPER technique.