Quantifying near-surface winds in tornadoes: A combined DOW-LES approach

Understanding the damaging nature of tornadic winds requires detailed knowledge of the three-dimensional vortex structure near the surface and how this structure then responds to changes in the surrounding flow. In order to address these objectives, a multifaceted approach has been adapted that utilizes DOW observations in conjunction with large-eddy simulations. First, the assumption of axisymmetry allows for the three-dimensional winds to be retrieved from single Doppler data. These retrievals, together with other derived quantities, are then used to diagnose vortex structure and dynamics. The axisymmetric velocities are also used to constrain a large-eddy simulation of the tornado vortex, with the objective of investigating how changes in the outer flow effect the corner region of the vortex. This paper will present results of the application of this novel approach to the 2004 May 12 Harper, KS tornado, and the 30 May 1998 Spencer, SD tornado.