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From Grid to Cloud: Understanding the Impact of Grid Size on Simulated Anvil Clouds and Atmospheric Profiles
  • Zeyuan Hu,
  • Nadir Jeevanjee,
  • Zhiming Kuang
Zeyuan Hu
Harvard University

Corresponding Author:[email protected]

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Nadir Jeevanjee
Geophysical Fluid Dynamics Laboratory
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Zhiming Kuang
Harvard University
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In this study, we explore the relationship between anvil cloud fraction and horizontal model resolution in small domain radiative-convective equilibrium (RCE) simulations, building on the findings of \citeA{jeevanjee22}. Using the System of Atmosphere Modeling (SAM) model, we find that finer resolutions yield higher anvil cloud fractions due to larger convective updrafts mass flux and increased mass detrainment at anvil levels. Employing two different microphysics schemes, we illustrate that finer resolution can enhance mass flux through either stronger cloud evaporation or weaker upper-troposphere stability, as the consequence of enhanced horizontal mixing. Moreover, we refine an analytical zero-buoyancy plume model to investigate the effects of adjusting entrainment rate and evaporation rate on vertical atmosphere profiles in a simple theoretical framework. Our solutions of the zero-buoyancy plume model suggest that stronger horizontal mixing can lead to larger convective updraft mass flux, consistent with the analysis in numerical simulations. We also observe the likelihood of atmospheric profiles converging at a grid size of approximately 100m, potentially as a result of converging entrainment rate and mixing strength. These insights have implications for global storm-resolving simulations, implying a possible convergence of high cloud and deep convection properties as the horizontal resolution approaches around 100m.
14 Oct 2023Submitted to ESS Open Archive
17 Oct 2023Published in ESS Open Archive