RESUME / ABSTRACT  


Simulations of stratocumulus

by


Adrian Lock
UK Met. Office






To the casual observer, stratocumulus is a dull grey slab of a cloud which has an irritating habit of hanging around for days on end doing nothing more exciting that drizzle in a depressingly persistent way, especially in England. It is this persistence and significant impact on the radiation budget, however, that make it of importance both to climate modeling and weather forecasting.

Numerical modeling of stratocumulus is complicated by the interaction between strong cloud-top radiative cooling and turbulent mixing which occurs just beneath a transition, often over just a few metres, to much warmer and drier air. This talk will describe the development of the UK Met Office boundary layer scheme, which allows these processes to interact in a realistic way on the relatively coarse vertical grids used in NWP, and illustrate its performance with results from the climate model. Results will also be presented from vertical column model tests of both the Met Office scheme and the RPN moist TKE boundary layer scheme for a case of marine stratocumulus. These illustrate the usefulness of such a simplified environment for identifying weaknesses in parametrizations and testing solutions.