Abstract:
This paper will examine the structure and evolution of the 8 May 2003 Central Oklahoma tornadic supercell using two different radars: the KTLX WSR-88D and the Central Oklahoma TDWR. Measurements of the vertical vorticity and convergence of each of three scales of rotation (mesocyclone, tornado cyclone signature [TCS], and tornadic vortex signature [TVS]) were made by subjectively choosing maximum outbound and inbound velocities from each time/elevation angle of each radar dataset. Data was graphed in the form of time-height plots of mesocyclone and TCS vorticity, and TVS delta-velocity, for both radars. Temporal variation of low-level convergence associated with the supercell was also analyzed. It was found that the TDWR, with much higher spatial and temporal resolution, was superior to the WSR-88D in resolving the evolution of small-scale storm features. The TCS was always more easily discernable in the TDWR velocity data. The TDWR velocity couplet associated with the TVS tracked very close to the tornado damage path, while the KTLX data was much less accurate at times. The TDWR was also able to resolve one or more surges on the rear-flank downdraft (RFD) that descended into the mesocyclone region and eventually was tied to the development of intense low-level convergence and the TCS. The KTLX WSR-88D did resolve an RFD surge, but it was difficult to track and observe in great detail because of the radar's lower temporal and spatial resolution. The TDWR data was also found to at times be difficult to interpret because of its ability to resolve detailed structures and its tendency to suffer velocity dealiasing failure. Nevertheless, the TDWR was shown to have advantages over the WSR-88D in observing important small-scale storm features.