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The Contributions of Shear and Turbulence to Cloud Overlap for Cumulus Clouds
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  • Anthony Sulak,
  • William Calabrase,
  • Shawn D Ryan,
  • Thijs Heus
Anthony Sulak
Michigan State University
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William Calabrase
Case Western Reserve University
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Shawn D Ryan
Cleveland State University
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Thijs Heus
Cleveland State University

Corresponding Author:[email protected]

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Vertical cloud overlap, the ratio of cloud fraction by area and by volume, for cumulus clouds are studied using large-eddy simulations (LES) due to the inefficient, wide-range values of cloud overlap. We can obtain information about the cloud cover of a cloud field by inspecting the individual clouds in that cloud field.We start with the maximum-random assumption and adjust this assumption for individual clouds.From this there is an under-prediction which leads to the conclusion that something can be added.We extend this by considering physical factors of cloud overlap: area variability, vertical wind shear, and turbulence. We use numerical schemes to calculate the effect of each contributor based on cloud height. We obtain great accuracy for our model of cloud overlap. Since there are multiple factors of cloud overlap, we look at the percentage of how much each contributes for a given binned cloud height. Furthermore, we get acceptable agreement for the calculated and actual total cloud cover. As such, we show that no other major contributors for cloud overlap and cloud cover exist. We end with an empirical model to describe the numerical schemes mentioned previously.
27 May 2020Published in Journal of Geophysical Research: Atmospheres volume 125 issue 10. 10.1029/2019JD032017