Publication Date:
2015-03-31
Description:
The Weather Research and Forecasting (WRF) model has been used to simulate clouds, and their effects on precipitation and radiation, in Africa. The results have been compared with observational databases, mainly based on satellite measurements. The CFMIP Observation Simulator Package (COSP) has been used to consistently compare simulated clouds with satellite data, allowing us to evaluate not only the total cloud cover but also the cloud amount of different cloud types, classified according to their optical thickness and top pressure. Nine WRF simulations, for the 2002–2006 period, were carried out to evaluate the influence of different physical parameterizations and model configuration on cloud cover. In general, model simulations show similar results, underestimating total cloud cover in most of the studied region. In the tropical convective area high clouds are underestimated, but the net effect over the radiation is partially compensated by the overestimation of cloud optical depth. Major differences appear over subtropical areas dominated by marine boundary layer clouds, mainly off the coast of Namibia. In this area, simulations show too many thick clouds and too few clouds with lower optical thickness. The net result is an underestimation of low cloud cover. Furthermore, the transition from stratocumulus to shallow cumulus away from the coast is also not realistically modeled.
Print ISSN:
0035-9009
Electronic ISSN:
1477-870X
Topics:
Geography
,
Physics
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