157 High-temporal Resolution Observations of the 27 May 2015 Canadian, Texas Tornado using the Atmospheric Imaging Radar

Thursday, 10 November 2016
Broadway Rooms (Hilton Portland )
Casey B. Griffin, Univ. of Oklahoma, Norman, OK; and D. J. Bodine, J. M. Kurdzo, and R. D. Palmer

On 27 May 2015, high-temporal resolution radar observations of an EF2 tornado were collected with the Atmospheric Imaging Radar (AIR) near Canadian, Texas.  The AIR is a mobile, X-band, imaging weather radar that uses digital beamforming to collect simultaneous 20º RHI scans while steering mechanically in azimuth to obtain volumetric data with very high temporal resolution.  During this deployment, 20º-by-80º sector volumes were collected every 5.5 s at ranges as close as 6 km, and data were collected during the mature and dissipating stages of the tornado.  During the mature stage, the tornado was 1 km in diameter and maximum Doppler velocities were near 65 m/s.  

The goal of this study is to examine rapid changes in tornado dynamics and reflectivity structure observed in AIR data.  The tornado undergoes a rapid transition from a large diameter with symmetric reflectivity and wind fields to a tornado characterized by an asymmetric wind field with embedded subvortices.  Rapid development of an intense near-surface anticyclonic vortex is also observed.  To explore the mechanisms causing these rapid changes, single-Doppler analyses are conducted, including three-dimensional axisymmetric wind retrievals and angular momentum analyses.  The tornado dissipation phase is also studied in order to investigate mesocyclone- and tornado-scale processes leading to dissipation.  Since the AIR collects data simultaneously in a vertical plane, tornado and mesocyclone vertical structure are also emphasized.

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