Simulation of Indian summer monsoon intra-seasonal oscillations using WRF regional atmospheric model

The present study examines the mean features of Indian summer monsoon and the boreal summer intra-seasonal oscillations (BSISO) as simulated by the Weather Research and Forecasting (WRF) regional atmospheric model. For this the WRF model at 30-km horizontal resolution is forced with NCEP-II reanalysis as the initial and boundary condition and integrated for a period of 8 years. The simulated results are compared with TRMM rainfall as well as with the reanalysis datasets of NCEP-II and ERA-Interim. Analysis reveals that the WRF model is able to reproduce the observed characteristics of large scale mean features and spatial variations of rainfall and winds at 850hPa and 200hPa. The northward propagating intra-seasonal oscillation (ISO) components over the monsoon trough and the equatorial Indian Ocean is reasonably simulated by the WRF model and shows some promise in understanding the regional characteristics of Indian summer monsoon and its ISO components. WRF model can act as suitable tool for predicting the ISO's over the Indian summer monsoon region. Further, the results presented here suggests that reanalysis with a realistic basic state and proper representation of northward moving ISO's is required to force a regional model. This study elucidate the WRF regional model has shown a reasonable representation of BSISO.