An examination of the structure of three tornadoes using high-frequency 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. Both the laboratory experiments as well as the numerical simulations have shown that structure of the tornado is highly dependent on the swirl ratio.

The Texas Tech University Ka-band radars (TTUKa; Weiss et al. 2009) are two 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 ten tornadoes.

This study will focus on the horizontal structure of three tornadoes using data collected by the TTUKa radars during VORTEX2. The three tornadoes that will be examined in this presentation occurred on June 13, 2010 tornado near Booker TX, May 18, 2010 near Stinnett, TX and May 25, 2010 near Tribune, KS. All three of these tornadoes were rated EF-0 on the Enhanced Fujita Sale. The evolution of the vortex structure will be diagnosed using the Ground- Based Velocity Track Display (GBVTD) technique of Lee et al. (1999). The appropriate scaling of tangential winds outside the radius of maximum wind for these weak tornadoes will be discussed as well as the variability of radial flow. In addition, the swirl ratio of the Stinnett tornado will be calculated and placed into the context of current conceptual models.