Simulation of Regional Climate over the Indian subcontinent through dynamical downscaling using WRF-ARW model

Regional climate data for the Indian subcontinent is generated using the WRF (Weather Research and Forecasting) model for the current climate period 1976–2005. WRF model at 25-km resolution was run in climate mode driven by boundary conditions from the Community Climate System Model version4 (CCSM4)—Coupled Model Intercomparison Project 5 (CMIP5) outputs of the historical simulation. The model outputs were categorized for the four different seasons and validated through comparison with global analysis fields. Assessment of the model performance is done through comparison of the spatial distribution of temperature, pressure, geopotential, wind and rainfall. The simulation results show the distinct features of the atmospheric patterns corresponding to each of the four seasons. The reversal of the meridional temperature gradients over Indian subcontinent and north Indian Ocean between the winter and pre-monsoon seasons is accurately produced. All the distinct features of the winter and southwest monsoon and the transition seasons are well simulated. The simulated pre-monsoon heating and post-monsoon cooling over the land are in good agreement with the analysis. Simulation of the rainfall with the highest percentage of annual rainfall during the southwest monsoon season over central plains and during the post-monsoon season over the south peninsula authenticates the performance of the ARW (Advanced Research WRF) model in climate integrations. WRF model simulations of the 2-m temperature and rainfall on subregional scale for 30 subdivisions of the Indian subcontinent are found to be better than CCSM4. The WRF-generated regional climate data at 25 km for the Indian subcontinent agree with the analysis, which would be useful for agriculture and water resource management applications and as a reference data base for future climate studies.