Kinematic and Polarimetric Observations of Tornadic Debris in the 10 May 2010 Norman, OK Supercell

The ability of tornadoes to loft non-meteorological scatterers that present irregular shapes and sizes and a wide range of dielectric constants and orientations allow polarimetric radars to discriminate between hydrometeors and tornadic debris.  The unique polarimetric signature associated with lofted non-meteorological scatterers is called the tornadic debris signature (TDS). While ties between TDS characteristics and tornado- and storm-scale kinematic processes have been speculated or investigated using photogrammetry and single-Doppler analyses, little work has been done to document the three‑dimensional wind fields associated with an evolving TDS.  Additionally, previous studies have documented through damage surveys and single-radar observations the sedimentation of tornadic debris, but kinematic documentation of debris transport is scarce.

This study uses data collected by KTLX and KOUN WSR-88D S-band radars as well as the University of Oklahoma’s Advanced Radar Research Center’s OU-PRIME C-band radar to construct single- and dual-Doppler analyses of a tornadic supercell that produced an EF-4 tornado near Norman, OK on 10 May 2010.  This supercell contains two TDSs in close proximity, and both TDSs exhibit asymmetric structure and distinct characteristics from each other.  The objective of this study is to relate the spatial distribution of polarimetric radar variables to kinematic fields such as vertical velocity and vertical vorticity, and elucidate the structure and formation mechanisms of asymmetries in the TDS.  Additional analyses will explore debris sedimentation using forward trajectories within the dual-Doppler wind field.