92nd American Meteorological Society Annual Meeting (January 22-26, 2012)

Sunday, 22 January 2012
Sensitivity of Microphysical Parameters on the Evolution of a Supercell
Hall E (New Orleans Convention Center )
Samuel P. Lillo, Plymouth State University, Keene, NH; and E. R. Mansell

Due to limited computational resources, critical microphysical processes must be accounted for in models through parameterization schemes. These schemes use many constants that have large uncertainties and may vary in nature spatially and temporally. By perturbing individual parameters within a single scheme, an ensemble can be created to attempt to account for the uncertainty in the model physics.

Five ensembles were created to test the sensitivity of a simulated supercell to the following parameters: cloud condensation nuclei (CCN) concentration, the efficiency of cloud water collection by graupel and hail, the fraction of liquid water allowed on graupel and hail, rime density function, and the drag coefficient as a function of particle density. A range of values was chosen for each parameter to represent the uncertainty that exists within the model microphysics. All ensembles exhibited growing variance through the simulation. Monotonic association to the storm evolution was most prominent in the CCN ensemble, in which there was also notable variance in the track and intensity of the supercell.

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