Assessment of WRF-Var assimilation for a cyclonic storm - Nisha

摘要

The present study is a case study of cyclonic storm Nisha to assess the impact of cold and cyclic mode assimilation schemes. The results from both the assimilation modes were compared with the results of Weather Research and Forecasting (WRF) simulations initiated with the initial conditions prepared from the global model forecast fields interpolated over the mesoscale model grid. So, the impact of WRF-3DVar assimilation over the numerical simulation of the cyclonic storm Nisha is also highlighted. WRF-3DVar simulations in cyclic mode have produced more intense cyclonic storms with stronger circulations and winds over 850 hPa pressure level and surface. The genesis, intensification and dissipation of the cyclone are better represented by the cyclic runs. The simulation and advection of higher quantity of moisture by WRF analyses in cyclic mode is one of the probable reasons for the over-intensification of the storm. The impact of assimilation is also well highlighted. It is quite evident that the initial conditions prepared through assimilation is superior to the initial conditions directly accepted from the global model forecasts.