Numerical simulation of tropical cumulus clouds and their interaction with the subcloud layer

Abstract

This two-dimensional numerical model differs from similar models in its greater emphasis on turbulent processes in the boundary layer and in clouds. In the model, cloud-scale dynamics are coupled with a third-moment turbulence closure. A turbulence-scale condensation scheme is used to parameterize the cloud water mixing ratio. We studied the response of tropical cumulus clouds to imposed large-scale vertical advection by doing two simulations: one with upward large-scale vertical velcocity (the "disturbed' case) and one without any (the "undisturbed' case) but otherwise identical. Deep cumulus clouds formed in the disturbed case, while only shallow clouds formed in the undisturbed case. -from Author