An Examination of the Vertical Structure of two tornadoes using Ka-band mobile doppler radar

Knowledge of the vertical structure of tornadoes is of great importance to meteorologists and civil engineers alike, albeit for different reasons. Meteorologists' interest in the vertical structure of tornadoes stems from a desire to better understand and predict the genesis, movement and dissipation of tornadoes, while the engineering community is interested in building structures that are better suited to withstand the winds of a tornado. The scientific communities' current understanding of tornado structure is based on simulations conducted in the laboratory (e.g., Church et al. 1979) as well as numerical simulations (e.g., Lewellen et al. 2000). Both the laboratory experiments as well as the numerical simulations have shown that structure of the tornado is highly dependent on the swirl ratio. More recently, fine-scale radar studies of tornado structure have added to the collection of knowledge about the vertical structure of the tornado vortex (e.g., Bluestein et al. 2004).

The Texas Tech University Ka-band radars (TTUKa) (Weiss et al. 2009) are two brand new tools that are well suited to the study of tornado vortex structure at a very fine-scale spatial resolution. The first radar was completed in the spring of 2009 in time to participate in the first year of the VORTEX2 field project. The second radar was finished in late winter 2010 and was available for the second year of the project. During the course of the project, the TTUKa radars successfully scanned multiple tornadoes.

This presentation will focus on the vertical structure of two tornadoes that were observed during VORTEX2, as revealed by range height indicator (RHI) scans. The first tornado that was successfully scanned occurred on 5 June 2009 near the town of Lagrange, WY; the second occurred on 13 June 2010 along the border between Texas and Oklahoma just north of the town of Booker, TX. The RHI scans of the two tornadoes show some structural differences. For example, the Lagrange case exhibited a single vortex structure while the Booker case exhibited a multiple vortex type structure at the time of the scans. Similarities and differences between these cases will be presented and placed into the context of previous theoretical and observational studies of the boundary layer and corner flow regions of tornadoes.