Increasing our Understanding of Lofted and Surface Debris Fields Associated with Tornadoes using Mobile Polarimetric Radars

Mobile, polarimetric radar data of tornadoes have increased our understanding of debris swaths and lofted debris. Numerical simulations have suggested that cycloidal damage swaths can result when debris is deposited as the low-level inflow turns upward in the corner region of the updraft annulus of the tornado core. This mechanism can dominate even when suction vortices are present in the simulations and can produce these swaths in the absence of these smaller-scale vortices. It is hypothesized that the observed cycloidal damage swaths are a result of the low-level inflow in the corner region of the tornado and not by the existence of suction vortices as hypothesized by schematic models proposed by Fujita. Observational evidence supporting this finding is presented.

Lofted debris is tracked using detailed photogrammetric techniques of a movie and is compared with single-Doppler velocities and the cross-correlation coefficient. Horizontal velocities of the debris tracks are compared with radar velocities for the first time. The case to be presented also provides a unique opportunity to compare the preferred orientation of the debris based on the visual images with the differential radar reflectivity.