Examination of the Relationships between Polarimetric Radar Signatures and Kinematic Processes Using High-Resolution WRF Simulations

Important relationships between kinematic processes and polarimetric radar signatures have been identified in past polarimetric radar studies of tornadic supercells. However, few studies have examined the relationship between kinematic processes and polarimetric radar signatures through non-idealized, high-resolution numerical simulations. The goal of this study is to examine how dual-polarization radar signatures evolve during rapid intensification and dissipation of low-level vortices in two simulated supercells. The study uses 1-min output from 1-km WRF simulations of tornadic supercells on 20 May 2013 and 31 May 2013 with maximum horizontal wind speeds reaching nearly EF-3 intensity in both simulations. WRF simulations using double-moment microphysics produce realistic polarimetric radar signatures of supercells, including the differential reflectivity (ZDR) arc and size sorting of ZDR within the hook echo. During low-level vortex intensification, low-level specific differential phase (KDP) structure evolves into a KDP “ball”. The cyclic evolution of these simulated polarimetric signatures will be investigated and compared to polarimetric radar observations. Finally, the vertical evolution of vortex intensification and dissipation are examined to explore top-down vs. bottom-up tornadogenesis and dissipation, which have been explored recently in high-temporal resolution Doppler radar studies.