Scaling Evaluation of the Effect of Surface Characteristics on Potential for Deep Convection over Uniform Terrain

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  • 1 Department of Agronomy, Iowa State University, Ames, Iowa
  • | 2 NOAA/NSSL,Norman, Oklahoma
  • | 3 NOAA/ERL/FSL, Boulder, Colorado
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Abstract

The effect of surface characteristics on the daytime change in the potential for development of deep convection resulting from surface flux of heat and moisture is evaluated by conceptual, scaling, and numerical modeling approaches. It is shown that deep convection depends significantly on the Bowen ratio; for smaller Bowen ratio, the thermodynamic potential for deep convection increases. The elevation and the intensity of the capping stable layer have an opposing impact on deep convection: 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 solar irradiance, it was found that development of fair weather cumulus has a secondary effect on deep convection potential. Observational and operational aspects of the influence of surface conditions on evapotranspiration and development of deep convection are presented.

Abstract

The effect of surface characteristics on the daytime change in the potential for development of deep convection resulting from surface flux of heat and moisture is evaluated by conceptual, scaling, and numerical modeling approaches. It is shown that deep convection depends significantly on the Bowen ratio; for smaller Bowen ratio, the thermodynamic potential for deep convection increases. The elevation and the intensity of the capping stable layer have an opposing impact on deep convection: 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 solar irradiance, it was found that development of fair weather cumulus has a secondary effect on deep convection potential. Observational and operational aspects of the influence of surface conditions on evapotranspiration and development of deep convection are presented.

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