Session 17B.1 The dynamical influences of cloud shading on simulated supercell thunderstorms

Thursday, 30 October 2008: 4:30 PM
South Ballroom (Hilton DeSoto)
Jeffrey Frame, Penn State University, University Park, PA; and P. M. Markowski and J. Petters

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It is found that the inclusion of both shortwave and longwave radiative transfer, along with surface fluxes of sensible heat, moisture, and momentum, can significantly effect simulated supercell thunderstorms. In particular, mesocyclone cycling frequency, peak updraft velocity, low-level vertical vorticity, precipitation efficiency, and storm motion are found to be altered, sometimes significantly, by the inclusion of the above parameterizations. The differences between these simulated storms are likely due to a combination of three processes: 1) The direct absorption and emission of shortwave and longwave radiation by the simulated cumulonimbus cloud; 2) The creation of a surface temperature deficit owing to the extinction of shortwave radiation by the anvil cloud; and 3) The modification of the larger-scale near-storm environment via fluxes of sensible heat, moisture, and momentum from the model surface. It is also found that the differences between the simulations with and without radiative forcing are more prominent in environments with less CAPE and more CIN than in other environments.
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