A Description of the Advanced Research WRF Model Version 4.1

This technical note describes the scientific and algorithmic approaches in the ARW Version 4, including its dynamical solver, physics options, initialization capabilities, boundary conditions, grid-nesting techniques, and data assimilation capabilities. ARW is supported as a community model by the National Center for Atmospheric Research, facilitating system development and broad use for research, operations, and education.

The modeling system supports atmospheric simulations across scales from large-eddy to global. ARWs applications include real-time NWP, weather events and atmospheric-process studies, data assimilation development, parameterized-physics development, regional climate simulation, air quality modeling, atmosphere-ocean coupling, and idealized- atmosphere studies.