4A.4 Dynamic Scale Awareness: Switching Parameterized Convection on at the Right Time

Tuesday, 24 January 2017: 9:15 AM
605 (Washington State Convention Center )
Ahmed Tawfik, NCAR, Boulder, CO; and D. Lawrence and P. A. Dirmeyer

As climate simulations approach convective permitting resolutions their needs to be a more dynamic way for convective parameterizations to be activated under the appropriate assumptions.  In particular, mass-flux parameterizations (among others) make the asymptotic assumption, which is to say that the area of a convective structure must be much smaller than the model grid area (i.e. sigma << 1). Using the Heated Condensation Framework as a means of parameterizing convective initiation, sigma can be directly calculated allowing for thesigma limits to be tested by turning off the deep convection scheme in CESM when the limit is violated.  This presentation explores a few different sigma limits and evaluates precipitation characteristics including extreme events.  Some mention will also be made regarding its use in Variable Resolution simulations to allow for a more dynamic scale awareness in locations that approach convective-permitting resolution.
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