16A.5 Rapid-scan analyses of supercells during tornadogenesis using a mobile, phased-array, X-band, Doppler radar

Thursday, 14 October 2010: 5:30 PM
Grand Mesa Ballroom F (Hyatt Regency Tech Center)
Michael M. French, Univ. of Oklahoma, Norman, OK; and H. B. Bluestein, I. PopStefanija, C. Baldi, and R. Bluth

During the spring storm seasons of 2008, 2009, and 2010 (the latter two periods were during VORTEX-2), a mobile, phased-array, X-band Doppler radar (the MWR-05XP) was used to obtain several datasets in supercells while tornadogenesis was occurring. The MWR-05XP utilizes a hybrid antenna with electronic scanning in elevation and mechanical scanning in azimuth. As a result, the MWR-05XP obtains electronic RHIs as it scans in azimuth. Vertical cross-sections of reflectivity factor and radial velocity are constructed from PPIs collected nearly simultaneously and, therefore, do not depend on storm-motion estimates or steady-state assumptions. It follows that the vertical structure of features like tornadoes and hook echoes can be studied over much shorter time scales and with more accuracy than that derived from traditional, mechanically scanning radars. On 23 May 2008, a dataset capturing tornadogenesis of a cyclonic tornado and the complete life cycle of an anticyclonic tornado was obtained using 14 second volumetric updates up to 20° in elevation angle. On 5 June 2009, during year one of VORTEX-2, the complete life cycle of a tornado in Goshen County, WY was documented using 7 second volumetric updates up to 20° in elevation angle. In 2010, during year two of VORTEX-2, datasets documenting tornadogenesis (10 May and 25 May) were obtained using 6-15 second volumetric updates up to 40° in elevation angle. The focus of the talk will be on the vertical evolution of TVS signatures during tornadogenesis, changes in the strength of the signatures in the vertical, and a unique observation of an abrupt vertical discontinuity in a TVS signature that develops and dissipates over very short time scales. Other possible discussion points include observations of changes in the vertical orientation of tornadoes and tornado dissipation. The talk will focus on data collected on 23 May 2008 and 5 June 2009, but data collected in 2010 also may be discussed, time permitting, as they pertain to the aforementioned topics.
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