Rapid-Scan Mobile Radar 3D GBVTD and traditional analysis of tornadogenesis

The Rapid-Scan Doppler On Wheels (DOW) 6-beam multi-frequency passive slotted waveguide phased array radar has collected data in several tornadoes, permitting the diagnosis of the rapid time evolution of these vortices. One such tornado was observed by both the Rapid-Scan DOW and a traditional DOW from ranges of 2-3 km, permitting high temporal (10 s) and spatial (30 m) resolution volumes to be collected. The traditional single-beam DOW observed the same tornado from a nearly co-located position, with updates at low levels of 20 s. 3D GBVTD techniques are used with both Rapid-Scan and traditional DOW data to deduce tangential and radial wind structures in the developing tornado. Intercomparisons of these fields, and deduced tornado structural parameters are used to validate the Rapid-Scan data. The collapse of a large > 1 km scale circulation to a much smaller tornado scale occurs nearly simultaneously at all observed altitudes, a phenomena that can only be revealed by very rapid-update volumetric data provided by the Rapid-Scan DOW.