12B.6
Comparisons of numerically-simulated and observed low-level polarimetric signatures in supercells

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Thursday, 19 September 2013: 9:45 AM
Colorado Ballroom (Peak 5, 3rd Floor) (Beaver Run Resort and Conference Center)
Daniel T. Dawson II, CAPS/Univ. of Oklahoma, Norman, OK; and E. R. Mansell, Y. Jung, L. J. Wicker, M. R. Kumjian, and M. Xue

Numerous recent studies have documented many interesting and possibly unique polarimetric signatures in supercells, including the ZDR arc and shield, the low-ZDR hail core signature, and the KDP foot, among others.  From a numerical simulation perspective, adequately simulating such features is of primary importance for the purposes of explaining their physical origin and evaluating the performance of microphysics schemes.  In this study, we perform idealized simulations of supercells using proximity soundings from observed supercell cases utilizing a sophisticated triple-moment bulk microphysics scheme.  We place emphasis on two of the most obvious low-level signatures in the ZDR field: the low- ZDR hail core, and the ZDR arc. We show that the triple-moment scheme performs better than its double- and single-moment counterparts in reproducing the observed nature of these features within the numerical simulation.  In addition, we discuss the physical nature of these features in the context of size sorting of both rain and hail by the storm-relative environmental wind profile.  Finally, we make preliminary comparisons of the simulated surface drop size distributions with those observed by disdrometers during VORTEX2.