A Nonhydrostatic Mesoscale Model Designed to Simulate Scale Interaction

Abstract

A three-dimensional nonhydrostatic mesoscale model is presented that is designed to optimally represent the scale-interaction process among inertially balanced and unbalanced modes occurring within convective weather systems. Because scale-interaction simulations are long-term integrations that emphasize the evolution of the three-dimensional kinetic energy spectrum, the model is built to conserve enstrophy, as well as kinetic energy against numerical sources and sinks in three dimensions. A non-Boussinesq and quasi-compressible framework is employed to maintain applicability on meso-α and larger scales as well as for situations of relatively large local density variation. Sample integrations in two and three dimensions are presented that show enstrophy conservation to be effective in improving the prediction of nonlinear evolution as truncation errors act to force anomalous bifurcations from the physical solution.