11D.3 The Dissipation Efficiency of Moist Convection and Tropical Cyclones

Wednesday, 30 April 2008: 1:45 PM
Palms I (Wyndham Orlando Resort)
David M. Romps, Univ. of California, Berkeley, CA

In radiative-convective equilibrium, surface sensible heating and condensation of water vapor add heat to the atmosphere at relatively warm temperatures, while the same amount of heat is removed from the atmosphere by radiation at relatively cool temperatures. Much like a heat engine, the larger the difference in the temperatures of heating and cooling, the larger the amount of work performed by the atmosphere. A few main factors determine this temperature separation, including the lapse rate, the Bowen ratio, and the precipitation efficiency. The difference in heating and cooling temperatures then leads to pressure work, which is partitioned into precip dissipation and wind-generated dissipation: the greater the convective lofting of condensed water, the smaller the amount of wind-generated dissipation. These insights can be used to explain the difference in the wind-generated dissipation of hurricanes as compared to more disorganized convection with the same heat fluxes.
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