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On the measurement of wind speeds in tornadoes with a portable CW/FM-CW Doppler radar [electronic resource].

Published
Washington, D.C. : United States. Dept. of Energy, 1991.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy.
Physical Description
Pages: (15 pages) : digital, PDF file
Additional Creators
Los Alamos National Laboratory, United States. Department of Energy, National Science Foundation (U.S.), and United States. Department of Energy. Office of Scientific and Technical Information
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Summary
Both the formation mechanism and structure of tornadoes are not yet well understood. The Doppler radar is probably the best remote-sensing instrument at present for determining the wind field in tornadoes. Although much has been learned about the non-supercell tornado from relatively close range using Doppler radars at fixed sites, close-range measurements in supercell tornadoes are relatively few. Doppler radar can increase significantly the number of high-resolution, sub-cloud base measurements of both the tornado vortex and its parent vortex in supercells, with simultaneous visual documentation. The design details and operation of the CW/FM-CW Doppler radar developed at the Los Alamos National Laboratory and used by storm-intercept teams at the Univ. of Oklahoma are described elsewhere. The radar transmits 1 W at 3 cm, and can be switched back and forth between CW and FM-CW modes. In the FM-CW mode the sweep repetition frequency is 15.575 kHz and the sweep width 1.9 MHz; the corresponding maximum unambiguous range and velocity, and range resolution are 5 km, {plus minus} 115 m s{sup −1}, and 78 m respectively. The bistatic antennas, which have half-power beamwidths of 5°, are easily pointed wit the aid of a boresighted VCR. FM-CW Data are recorded on the VCR, while voice documentation is recorded on the audio tape; video is recorded on another VCR. The radar and antennas are easily mounted on a tripod, and can be set up by three people in a minute or two. The purpose of this paper is to describe the signal processing techniques used to determine the Doppler spectrum in the FM-CW mode and a method of its interpretation in real time, and to present data gathered in a tornadic storm in 1990. 15 refs., 7 figs.
Report Numbers
E 1.99:la-ur-91-556
E 1.99: conf-9104193--1
conf-9104193--1
la-ur-91-556
Subject(s)
Other Subject(s)
Note
Published through SciTech Connect.
01/01/1991.
"la-ur-91-556"
" conf-9104193--1"
"DE91008589"
": ATM-8902594"
3. tornado symposium, Norman, OK (USA), 2-5 Apr 1991.
Unruh, W.P.; Bluestein, H.B. . School of Meteorology.
Funding Information
W-7405-ENG-36
View MARC record | catkey: 14148357