A Fully Compressible Nonhydrostatic Deep-Atmosphere Equations Solver for MPAS

Abstract A solver for the nonhydrostatic deep-atmosphere equations of motion is described that extends capabilities Model Prediction Across Scales-Atmosphere (MPAS-A) beyond existing shallow-atmosphere solver. The discretization and additional terms within this extension maintain C-grid staggering, hybrid height vertical coordinate, spherical centroidal Voronoi mesh used by MPAS, also preserve solver’s conservation properties. Idealized baroclinic wave test results, using Earth-radius reduced-radius sphere configurations, verify correctness compare well with published results from other models. For these cases, time evolution maximum horizontal wind speed, total energy its components, are presented as solution metrics may allow further discrimination in model comparisons. case solutions found to be sensitive configuration dissipation mechanisms MPAS-A, many differences among models previously appear arise because their differing configurations. case, small-scale noise numerical was analytic initialization contains unstable lapse rates tropical lower troposphere. By adjusting a parameter initialization, instability removed unphysical large-scale overturning no longer occurs. Inclusion capability MPAS-A increases dry dynamics cost less than 5% on CPU-based architectures, either shallow- or controlled simple switch.