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of tornadoes in Kansas and Texas were collected using the new airborne Doppler
radar system ELDORA (Electra Doppler Radar) aboard an NCAR P-3 aircraft,
under the guidance of Roger Wakimoto from UCLA. In 1994 the FAST scanning
technique included scans not only in the plane of the track of the aircraft, but also
at other elevation angles, as each fore and aft scan sequence included a rotation
about the axis of the flight track ( Figure A.3 ) .
VORTEX also marked the first use of a mobile mesonet, whose instrumented
vehicles were used to make in situ thermodynamic and wind measurements in
strategically selected locations within supercells. The mobile mesonet was devel-
oped by Jerry Straka at OU and by Erik Rasmussen and Sherman Fredrickson
at NSSL. Mobile soundings were obtained using a system recently developed
at NCAR in Boulder, Colorado, which made use of radio navigation aids
(M-CLASS: Mobile Cross chain LORAN Atmospheric Sounding System) to
locate the sonde packages (these instruments have since been superseded by
sondes that use GPS navigation information). VORTEX was an important mile-
stone in that it was coordinated, making use of a number of different observing
platforms, some old and new. The second year of VORTEX was significant also
because Josh Wurman at OU, with collaboration among OU, NSSL, and NCAR
(including Jerry Straka, Erik Rasmussen, Mitch Randall, and Allen Zahrai), built
a truck-mounted, pulsed Doppler radar system named the Doppler on Wheels
(DOW). The DOW made the first successful volumetric maps of the wind field in
tornadoes, at X-band, in 1995, during VORTEX. Finally, an instrument package
(a later generation version of the Turtle) from Bill Winn at New Mexico Tech was
placed directly in the path of a tornado and successful thermodynamic measure-
ments were made.
After VORTEX, smaller field programs were conducted on an almost annual
basis in the late 1990s and afterwards using the DOW and subsequent versions
of the DOW during ROTATE (Radar Observations of Tornadoes and Thunder-
storms Experiment). Sporadic, unnamed, small field programs were conducted
collaboratively by the University of Massachusetts and the University of
Oklahoma with the U. Mass. W-band radar and the U. Mass. X-band radar. The
latter was first used in 2001 without Doppler or polarimetric capabilities, but in
2002 was expanded to include them. Two C-band mobile Doppler radars
(SMART-R, Shared Mobile Atmospheric Research and Teaching Radar) devel-
oped at Texas A&M University, the University of Oklahoma, NSSL, and Texas
Tech University were used in Oklahoma in 2004 to obtain dual-Doppler coverage
of a tornadic supercell. The Rapid (X-band) DOW made its debut in 2005 and the
Naval Postgraduate School MWR-05XP (Meteorological Weather Radar-2005,
X-band, Phased Array) made its debut in 2007. Both radars scan electronically in
elevation but mechanically in azimuth. The latter also includes limited electronic
scanning in azimuth to keep the beam nearly stationary in space and frequency
hopping to increase the number of independent samples.
Since VORTEX, many single and some dual-Doppler data sets have been
collected of supercells and tornadoes. Of these, the most significant were the
first mobile dual-Doppler data set collected in a tornadic supercell
in eastern
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