Central to tropical cyclogenesis is the changing behavior of moist convection as the cyclone evolves. Based on a cumulus ensemble model run in weak temperature gradient mode, we suggest that the mid-level vortex created by early-stage convection stabilizes the environment in way that favors further development. In particular, modeled convection occurring in the more stable environment produces ...

Cumulus parametrization started with simple attempts to represent the subgrid-scale effects of convective clouds. Manabe et al. (1965) proposed adjustment towards a moist adiabatic structure in the presence of conditional instability, and Kuo (1965, 1974) proposed a simple cloud model to redistribute the heating and moistening effects of precipitating clouds in the presence of grid-scale moistu...

24 25 Tropical intraseasonal variability is examined in version 3 of the Geophysical Fluid Dynamics 26 Laboratory Atmosphere Model (AM3). Compared to its predecessor AM2, AM3 uses a new treatment 27 of deep and shallow cumulus convection and mesoscale clouds. The AM3 cumulus parameterization is 28 a mass flux-based scheme but also, unlike that in AM2, incorporates subgrid-scale vertical velocit...

We model the ascent of warm, moist air in the Earth’s atmosphere by turbulent convection and expansion with the KPZ equation, familiar in the physics literature on surface growth. Clouds form in domains where the interface between the rising air and its surrounding air achieves an elevation higher than that necessary for condensation. The model predictions are consistent with the perimeter frac...

Prior research has shown that deforestation in the southwestern Amazon enhances the formation of nonprecipitating shallow cumulus clouds, while deep cumulus convection was favored over forested land. The research presented here further investigates the trends of hydrometeors in the area by examining how precipitation frequency changes as a function of distance to the forest’s edge. Measurements...

The enhanced cumulus convection in tropical disturbances acts in two opposing ways. In one sense the condensation heat from the cumulus acts to warm the inner portions of the disturbance and induce vertical shear of the horizontal wind through the thermal wind relationship. In the opposite sense the cumulus also act to suppress vertical wind shear by transfer of horizontal momentum within their...

4 characteristics is investigated using large-eddy simulations (LES) of the re-5 sponse of shallow cumulus convection to a small-amplitude temperature per-6 turbation that is horizontally uniform and localized in height. The simulated 7 cumulus fields are analyzed in the framework of an ensemble of entraining 8 plumes by tracking a large number of Lagrangian parcels embedded in the 9 LES and gr...

To provide a theoretical basis for stochastic parameterization of cumulus convection, the equilibrium fluctuations of a field of cumulus clouds under homogeneous large-scale forcing are derived statistically, using the Gibbs canonical ensemble from statistical mechanics. In the limit of noninteracting convective cells, the statistics of these convective fluctuations can be written in terms of t...