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Advances in Meteorology
Volume 2014 (2014), Article ID 597378, 7 pages
http://dx.doi.org/10.1155/2014/597378
Research Article

Wind Field of a Nonmesocyclone Anticyclonic Tornado Crossing the Hong Kong International Airport

1Center for Severe Weather Research, 1945 Vassar Circle, Boulder, CO 80305, USA
2Hong Kong Observatory, 134A Nathan Road, Hong Kong

Received 19 October 2013; Revised 24 December 2013; Accepted 31 December 2013; Published 2 March 2014

Academic Editor: Sven-Erik Gryning

Copyright © 2014 Karen A. Kosiba et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

A nonmesocyclone tornado traversed the Hong Kong International Airport on September 6, 2004 directly impacting a surface weather station. This allowed for 1-second 10-meter above ground level (AGL) wind observations through the core of the tornado. Integration of these 10-meter AGL wind data with Ground-Based Velocity Track (GBVTD) wind retrievals derived from LIDAR data provided a time history of the three-dimensional wind field of the tornado. These data indicate a progressive decrease in radial inflow with time and little to no radial inflow near the time the tornado crosses the surface weather station. Anemometer observations suggest that the tangential winds approximate a modified-Rankine vortex outside the radius of maximum winds, suggesting that frictionally induced radial inflow was confined below 10 m AGL. The radial-height distribution of angular momentum depicts an increase in low-level angular momentum just prior to the tornado reaching its maximum intensity.