75th Annual Meeting of the APS Division of Fluid Dynamics (November 20, 2022 — November 22, 2022)

P0007: The texture of atmospheric humidity: Near-surface turbulence in precipitating cumulus convection

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Authors

• Georgios Matheou, University of Connecticut
• Ravon Venters, University of Connecticut
• Oumaima Lamaakel, University of Connecticut
• Joao Teixeira, Jet Propulsion Laboratory, California Institute of Technology

DOI: https://doi.org/10.1103/APS.DFD.2022.GFM.P0007

The atmosphere is in a perpetual motion. Near the surface, in the atmospheric boundary layer, the atmosphere is often turbulent. The character of boundary layer turbulence influences the formation of clouds, storms, and air quality. The image was created from a large-eddy simulation of precipitating trade-wind cumulus clouds. The image shows a combination of specific humidity and vertical velocity on a horizontal plane 300 m above the ocean surface. Specific humidity is plotted with color contours (lighter colors is moister atmosphere) and vertical velocity is overlayed as a varying transparent shading (more transparent/lighter shading is larger vertical velocity). The shading “texturizes” the humidity field and creates an appearance of depth. In the atmosphere, turbulence is not merely multi-scale, but its nature can vary within short distances. In the image, convection fronts sweep through convection- and shear-induced streaks to form regions of reduced vertical transport. Eventually, convection breaks through and regenerates. The present large-eddy simulation was carried out to understand the variable nature of turbulence in the boundary layer and to study the development of large horizontal coherent structures. The simulation results are used to develop and evaluate convection parameterizations in weather and climate models, helping improve the accuracy of weather forecasts and climate projections.