Including a Cold Pool Representation in a Convection Parameterization and Simulating Its Impacts on the Spatial and Temporal Variability of the Precipitation in the NASA GEOS-5 GCM

We developed and implemented a simple representation of a cold pool in the Grell-Freitas convection parameterization. The cold pool parameterization is based on the observation that convective-scale downdrafts produce a local ‘deficit’ of the environmental moist static energy. This information is advected and becoming downwind available to trigger and intensify new convection. The cold pool is dissipated by a simple exponential decay using a lifetime of a few hours, or by interacting with the underneath surface by exchanging latent and sensible heat fluxes.
Preliminary, results look promising with a substantial improvement of the simulation of the diurnal cycle of the precipitation over the land, mainly the nighttime representation. We will also discuss aspects of changes in the spatial variability of the precipitation simulated by the NASA GEOS-5 GCM with the new approach.