Casey Griffin-March 3

High-temporal Resolution Observations of the 27 May 2015 Canadian, Texas, Tornado using the Atmospheric Imaging Radar and Kinematic and Polarimetric Observations of Tornadic Debris in the 10 May 2010 Norman, Oklahoma, Supercell

The first portion of this two-part seminar overviews data collected of an EF-2 near Canadian, Texas on 27 May 2015 by the Atmospheric Imaging Radar (AIR).  The AIR is a mobile, X-band, imaging radar that uses digital beamforming to collect simultaneous RHI scans while steering mechanically in azimuth to obtain high-temporal weather data.  During this deployment, 20º-by-80º sector volumes were collected every 5.5 s at ranges as close as 6 km.  This study documents the rapid vortex structure changes associated with the dissipation stages of the tornado.  Axisymmetric analyses will be used to interrogate changes in tangential flow and reflectivity structure associated with a decreasing tornado core diameter and a transition from a two-cell to a one-cell vortex flow.  Finally, a high-temporal angular momentum budget will be presented.

The second part of this seminar overviews 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 of the 10 May 2010 Norman, Oklahoma, tornadic supercell.  Dual-Doppler and single-Doppler polarimetric analyses are used to interrogate two tornadic debris signatures (TDSs) associated with EF-4 and EF-2 tornadoes that exist in close proximity to one another.  Differences in the spatial distribution of polarimetric variables within the two TDSs will be discussed along with an observation of large volume of debris ingestion by the supercell’s storm-scale updraft.  Finally, future work involving kinematic controls on observed TDS asymmetries and debris sedimentation will be outlined.