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Dual-doppler Analysis of Winds and Vorticity Budget Terms Near A Tornado


Three-dimensional dual-Doppler observations with unprecedented finescale spatial and temporal resolution are used to characterize the vector wind field and vorticity generation terms in and near a weak, short-lived tornado. The beam widths of the two Doppler on Wheels (DOW) mobile radars, at the range of the tornado, are 250 m with gate lengths of 75 m, resulting in a resolution of less than 10(7) m(3). One of the DOWs collected data during the 240 s prior to the formation of the tornado, enabling examination of the genesis process. A single set of volumetric scans suitable for dual-Doppler analyses were completed by both DOWs, permitting the calculation of vertical and horizontal vorticity, divergence, and stretching and tilting terms in the vorticity budget of the large but weak tornado and its surroundings, but no local tendency terms. Analyses of the dual-Doppler vector wind fields document, for the first time in a supercellular tornado, revealed several structures expected to be associated with tornadoes, including the tilting of horizontal vorticity into the vertical near the tornado, and stretching of vertical vorticity in the region of the tornado. The analyses are compared to conceptual and computer models of tornadic storms, confirming the existence of various phenomena and processes, although some model predictions, particularly those concerning the distribution of horizontal vorticity, could not be verified through these analyses. The observed magnitudes of stretching of vertical vorticity and tilting of horizontal vorticity are consistent with those necessary for generating the observed vorticity near the tornado.

Article / Publication Data
Available Metadata
Fiscal Year
Publication Name
Monthly Weather Review
Published On
June 01, 2007
Publisher Name
Amer Meteorological Soc
Print Volume
Print Number


Not available


Authors who have authored or contributed to this publication.