Improved detection of WSR-88D mesocyclone signatures during the Oklahoma tornado outbreak of 3 May 1999

Using a mesocyclone model and a simulated WSR-88D Doppler radar, our recent studies have shown that a stronger mesocyclone signature is produced using 0.5 deg azimuthal sampling instead of conventional 1.0 deg sampling. Two reasons for producing the stronger signature are (a) the effective beamwidth resulting from 0.5 deg azimuthal sampling is narrower than that for 1.0 deg azimuthal sampling, and (b) with twice the azimuthal density of data points, there is better sampling of the peaks of the mesocyclone signature. Furthermore, the signature can be detected at least 50 percent farther away from the radar with 0.5 deg azimuthal sampling than with conventional 1.0 deg azimuthal sampling. To verify the above simulated findings, Archive Level I (time-series) data were collected at the WSR-88D Operational Support Facility's KCRI radar site in Norman during the tornado outbreak of 3 May 1999. With time-series data, two Archive Level II data tapes were produced - one having 0.5 deg azimuthal data collection and the other having 1.0 deg azimuthal data collection. Results show that mesocyclone signatures are stronger using 0.5 deg azimuthal sampling compared to the conventional 1.0 deg azimuthal sampling of the WSR-88D.