SCALING EVALUATION OF THE EFFECT OF SURFACE CHARACTERISTICS ON POTENTIAL FOR DEEP CONVECTION OVER UNIFORM TERRAIN

The effect of surface characteristics on the daytime change in the pot ential for development of deep convection resulting from surface flux of heat and moisture is evaluated by conceptual, scaling, and numerica l modeling approaches. It is shown that deep convection depends signif icantly on the Bowen ratio; for smaller Bowen ratio, the thermodynamic potential for deep convection increases. The elevation acid the inten sity of the capping stable layer have an opposing impact on deep conve ction: increasing moisture accumulation through evapotranspiration was supportive but was counteracted by the enhancement of dry entrainment . Based on an approximate treatment of the effect of cloudiness on sol ar irradiance, it was found that development of fair weather cumulus h as a secondary effect on deep convection potential. Observational and operational aspects of the influence of surface conditions on evapotra nspiration and development of deep convection are presented.