RELEASE OF POTENTIAL INSTABILITY - 1. A SEQUENTIAL PLUME MODEL WITHIN A HYDROSTATIC PRIMITIVE EQUATION MODEL.

Abstract

The authors attempt to clarify the potential instability release process within a framework that will permit calculation of convective/mesoscale interactions. The approach is to use an extension of the Lagrangian form of the one-dimensional cumulus model to provide values of convective-scale changes to a hydrostatic primitive equation model. This cumulus subroutine locates the base of the convection, computes the cumulus plume that will build, accounts for the environmental subsidence, and mixes the subsided environment with the cumulus plume after rainout. The convection model is explained in some detail along with its behavior within the hydrostatic model. The use of this scheme for convective adjustment is contrasted with other schemes; it is emphasized that this scheme is more generally applicable and includes the temporal evolution of mesoscale convective disturbances through consumption of pre-existing potential instability as well as the resupply of warm moist air (fuel).