Summaries - Office of Research & Innovation
Back Small-Scale Thermodynamic and Dynamic Mechanisms for Growth of Shallow Cumuliform Clouds
|Division||Graduate School of Engineering & Applied Science|
Peters, John M.
|Sponsor||Office of Naval Research (Navy)|
|Summary||Cumulonimbus clouds are central to the redistribution of boundary layer moisture through the rest of the troposphere. Therefore, they impact atmospheric phenomena across a wide range of spatial scales. The growth of boundary layer thermals into shallow cumuli and their subsequent growth into deeper cumulonimbus occurs on length scales of less than 1 kilometer and is challenging for models to represent. Global models of the atmosphere generally cannot yet resolve such fine-scale processes because of the computational expense of doing so; therefore, boundary layer thermal and shallow cloud properties must be parameterized. Proper simulation of these features requires robust observational datasets that can guide the improvement of physical parameterizations in models. One example of a process that requires better understanding in order to improve physical parameterization is the dependence of cloud updraft radius on the cloud environment. The proposed work includes a field experiment (CALICO) that will sample the boundary layer, free troposphere, and shallow convection in near-coastal environments during wintertime post-frontal convection along the U.S. West Coast. Measurements of fluxes of energy and buoyancy between the ocean and atmosphere, free tropospheric environmental buoyancy, aerosol concentration, and in-cloud hydrometeor size distributions will be collected. High-resolution simulations of observed clouds, forced by soundings collected during CALICO and anchored to the aircraft and radar observations, will provide three-dimensional representation of the atmosphere in which the aircraft flies. Data from a ground-based scanning cloud radar will be used to track convection and characterize the morphology of clouds in three dimensions. The combination of aircraft and radar data with high-resolution model output will be used to inform future improvements in convective and microphysics parameterizations.|
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