12.6 How do surface fluxes influence cold pool evolution?

Wednesday, 5 August 2015: 2:45 PM
Republic Ballroom AB (Sheraton Boston )
Leah D. Grant, Colorado State University, Fort Collins, CO; and S. C. van den Heever

Cold pools are ubiquitous in the atmosphere, and their role in the structure and maintenance of convective storm systems and in convective initiation is widely recognized. It is therefore important to understand cold pool dynamics and characteristics for the various environmental regimes in which they occur. High-resolution idealized numerical models have long been used to study cold pool dynamics in different environments, such as under varying wind shear and stability profiles. However, there have been very few studies investigating the quantitative impacts of surface sensible and latent energy fluxes on cold pools. Surface fluxes are important for cold pool characteristics because they may aid in the demise of cold pool temperature and moisture anomalies and impact the distribution of moisture within the cold pool with subsequent implications for convective initiation, particularly in tropical environments. The goal of this study is therefore to investigate the quantitative influence of surface latent and sensible energy fluxes on isolated cold pool characteristics, including cold pool intensity, propagation speed, vertical velocity, dissipation rate, and distribution of moisture within the cold pool. A suite of 2D, idealized, high-resolution modeling simulations with horizontal (vertical) grid spacings of 50 m (25 m), varying surface flux configurations, and without microphysics have been performed in order to achieve this goal. The results suggest that the largest impact of surface fluxes on cold pool characteristics occurs through their influence on turbulent entrainment rates of environmental air into the cold pool, and that direct modification of the cold pool buoyancy and moisture by surface fluxes plays only a minor role in the cold pool evolution.
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