Grouping of Clouds and Internal Gravity Waves in a Non-Hydrostatic Model of MoistConvection

摘要

A nonhydrostatic model for moist convection is formulated to study somefundamental aspects of cumulus dynamics, in particular, cloud grouping through gravity wave interactions. The Boussinesq approximated equations of motion are used and the convective cells are assumed to extend vertically through the entire model domain. A hydrological cycle is included where condensed water is advected with the motion field and removed through precipitation. The three dimensionality of the model does not alter the qualitative conclusions from an earlier two dimensional study, but gives a more realistic spatial distribution of clouds. The inclusion of the cloud water favors the generation of internal gravity waves and thus, the grouping of clouds. The model sensitivity to parameters is systematically studied. The stratification of the atmosphere, the dissipation of the model, and the autoconversion rate of cloud water are the most important parameters in determining the model clouds and the development of moist convection. Results also point out some aspects of moist convection, which should be taken into account when parameterizing moist convection in mesoscale numerical models.