A Description of the Advanced Research WRF Version 4

The Weather Research and Forecasting (WRF) Model isan atmospheric modeling system designed for both research and numerical weather prediction. WRF is an open-source community model, and has been adopted for research at universities and governmental laboratories, for operational forecasting by governmental and private entities, and for commercial applications by industry.The ARW is a configuration of the WRF system featuringthe ARW dynamics solver together with other compatible components to produce a simulation. Thus, it is a subset of the WRF system that, in addition to the specific solver, encompasses physics schemes, numerics/dynamics options, initialization routines, and a data assimilation package (WRFDA).