Shawn Handler-July 19

Simulated and Observed Bulk Microphysical Characteristics of Midlatitude Mesoscale Convective Systems

In 2013, the fleet of NEXRAD WSR-88D radars were upgraded to dual-polarization capabilities. Unlike conventional single-polarization radar, dual-polarization allows for the identification of particle shape, size, orientation, and concentration within a radar sample volume due to the addition of new radar variables which include differential reflectivity (Z_DR), specific differential phase (K_DP), and the co-polar correlation coefficient (ρ_HV).

In this study, NEXRAD WSR-88D polarimetric radar observations are leveraged to create large-area three dimensional composites to better understand bulk (typical) hydrometeor distributions and their associated microphysical characteristics within midlatitude mesoscale convective systems. The motivation for a study of this kind is to show the utility in using a rich dataset of polarimetric observations to identify observed hydrometeor distributions within a specific storm type, and to gauge model performance by examining simulated hydrometeor distributions subject to multiple microphysics parameterizations.

A hydrometeor classification algorithm (HCA), a novel radar echo identification algorithm, and the NARR dataset are used to examine both simulated and observed hydrometeor distributions in light of storm lifecycle, storm structure, and storm environment. The 2D idealized squall line in WRF was used to compare the observed hydrometeor distributions to those simulated from a model using a polarimetric radar data simulator (PRDS). We also demonstrated how microphysical variables from a model and the simulated polarimetric radar variables can improve hydrometeor classification.