Sunday, 10 August 2003: 10:30 AM
The vertical structure of the Happy, Texas tornado of 5 May 2002: Mobile, W-band, Doppler-radar observations
An outstanding problem in the kinematics and dynamics of tornadoes is determining the vertical wind profile at low levels and what causes it. In particular, it is not known well how the wind speed varies in nature in the lowest several hundred meters. This problem is of particular interest to the wind engineering community. To further our understanding of how the wind varies in tornadoes near the ground, we have collected RHIs with the Univ. of Massachusetts, truck-mounted, W-band Doppler radar, through a tornado in Happy, TX on 5 May 2002. Ultra-high spatial resolution was achieved, owing to the 0.18 deg half-power beamwidth of the antenna. Following sector scans at 5 km range, RHIs were collected on both the right and left sides of the tornado from near the ground up to about 1 km AGL, depending upon the range, which was generally around a few km. This paper will discuss the vertical profile of Doppler velocity and reflectivity associated with the tornado. The center of the tornado was marked by a 250-m wide reflectivity hole that widened with height above 500 m, and tilted with height toward the radar. Significant layers of vertical shear were evident about 200 m AGL. Evidence of 500-m deep vertical circulations was also found.