Putting a radar on the road was once a novelty. Doppler on Wheels (DOW)
came to life nearly ten years ago, built on a relative shoestring through
NCAR, NSSL, and the University of Oklahoma (OU). The truck-mounted radar
and its younger siblings soon leapt to prominence on their annual circuit
across Tornado Alley. They have since gathered landmark data on multiple
tornado vortices, hurricane eyes, and other mesoscale features.
The new rapid-scan DOW at work on a tornadic supercell near Stratford,
Texas. (Photos by Carlye Calvin.)
Today, several other portable radarssome solo, some in setsmake
up an increasingly crowded, competitive field. They include:
A series of short-wavelength units built by the Los Alamos
National Laboratory and University of Massachusetts since 1987 and deployed
by Howard Bluestein (OU). One caught near-surface winds of 460 km/hr
(286 mph) in an Oklahoma tornado in 1991. In recent years Bluestein
and UMass have deployed a 3-mmwavelength radar specifically designed
to track tornadoes. The biggest success thus far, says Bluestein, was
from a 2002 tornado in Happy, Texas. We have data on the vertical
structure of this tornado at unprecedented spatial resolution.
Bluestein also collected data on several tornadoes this spring at close
range with multiple polarizations using a 3-cm radar from UMass.
The Shared Mobile Atmospheric Research and Teaching Radar (SMART-Radar),
led by OUs Michael Biggerstaff and produced through support from
NSSL, OU, Texas Tech University, and Texas A&M University. First
deployed in 2001, the original SMART-Radar has documented three hurricanes,
a number of tornadoes, several mesoscale convective systems, and interactions
between fronts and boundary-layer rolls. A second SMART-Radar, delayed
by a fire at NSSL in July 2001, arrived in May.
The Seminole Hurricane Hunter (Florida State University), a
portable, dual-polarization radar to be evaluated later this year by
a team from Colorado State University and ATD.
This spring the UMass, SMART-Radar, and two DOW units all caught a
tornado-producing storm that struck northwest Oklahoma City on 9 May,
only a day after the suburb of Moore was pummeled. Add to this
the proximity of the terminal Doppler radar at Will Rogers World Airport
and the (NWS) WSR-88D radar, and there should be plenty of data available
for intercomparison and case studies of this event, says OU graduate
student and DOW assistant Bob Conzemius.
The latest DOW debuted this spring as the first mobile Doppler to
operate in rapid-scan mode. Transmitting through an array of 86 slotted
waveguides (pictured at right), the radar sends six simultaneous beams
and collects a three-dimensional picture every 10 to 15 seconds. The
rapid-scan DOW was built largely at NCARs Design and Fabrication
Services, with a team of ATD engineers and technicians (including leads
Jonathan Lutz and Mitchell Randall) working with DOW founder Joshua
Wurman. Now an NCAR affiliate scientist, Wurman operates the NSF-supported
DOWs through the nonprofit Center for Severe Weather Research in Boulder.
DOW software engineer Mitchell Randall (second from
left) and Joshua Wurman (second from right) join the staff from NCAR's
Design and Fabrications Services who built DOW: (left to right) David
Allen, Jack Fox, Jerry Dryer, Stephen Rauenbuehler, Edward Mores,
Bart Woodiel, and Walter Hodshon.
A few of the new DOW's 86 slotted waveguides.
The new DOW struck pay dirt near Stratford, Texas, on 15 May (see
photo above), when it gathered rapid-scan data on a prolific storm that
produced two simultaneous cyclonic tornadoes, with an anticyclonic circulation
in between. All told, the DOWs saw over a dozen days in action this