10B.6 An Investigation of the Relationship between Doppler Vortex Signatures and Polarimetric Debris Signatures in Damaging Tornadoes

Wednesday, 24 October 2018: 3:15 PM
Pinnacle AB (Stoweflake Mountain Resort )
Zachary B. Wienhoff, Univ. of Oklahoma, Norman, OK; and H. B. Bluestein, L. J. Wicker, D. J. Bodine, B. L. Cheong, D. W. Reif, and N. Dahl

In recent years, several high spatiotemporal resolution datasets have been collected by a rapid-scan, X-band, polarimetric Doppler radar (RaXPol) operating near strong tornadoes. In many of these cases, strong divergence in the sampled velocity field was observed during periods of heavy debris loading, followed by oscillating convergent and divergent signatures after debris is shed from the vortex. These observations have often been accompanied by significant deviations in the tornado’s track and substantial changes in intensity. While these observations have prompted interesting questions regarding potential effects of debris on tornado vortices, the inability of typical Doppler radar observations to distinguish between the background flow and the flow of debris in a tornado has hindered obtaining answers to those questions.

Doppler and polarimetric spectra can be created from these observations using I/Q data, which may theoretically allow for the decomposition of air and debris motions within strong tornadoes given a sufficient number of collected samples. This presentation will examine I/Q data generated using a polarimetric Doppler radar simulator to assess (1) the ability of Doppler and polarimetric spectra to capture different flow regimes within a strong tornado and (2) the logistical feasibility of applying this technique in field observations. The radar simulator used in this study (SimRadar) emulates the collection of I/Q radar data and trajectories of both hydrometeors and several types of tornado debris, which allow us to evaluate the effects of heavy debris loading on the radar signal. Analyses from SimRadar of a controlled simulation will be examined, and results will be compared to I/Q data collected by RaXPol in a tornadic supercell.

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