Adaptive grid refinement for two-dimensional and three-dimensional nonhydrostatic atmospheric flow

The adaptive technique makes use of separate rectangular refinements to increase resolution where truncation error estimates are large. Multiple, rotated, overlapping grids are used along with an arbitrary number of discrete grid-refinement levels. Refinements are placed and removed automatically during the integration based on estimates of the truncation error in the evolving solution. The adaptive model integrates the compressible, nonhydrostatic equation of motion. A splitting technique is used to accommodate the sound waves by advancing certain terms with a separate smaller time step. The terms responsible for gravity waves are also integrated with the smaller time step, and with the acoustic modes filtered through the use of divergence damping the resulting model can be run as efficiently as hydrostatic models. The adaptive technique is shown to be efficient when compared to single fixed-grid simulations. -from Authors