Geoscience Reference
In-Depth Information
Oklahoma in 1997, single-Doppler coverage of a tornadic supercell in Spencer,
South Dakota in 1998, single-Doppler coverage (at X-band and W-band) of large
tornadoes in central Oklahoma on May 3, 1999 during a major tornado outbreak
and of tornadoes in Kansas and Oklahoma in 2004, rapid scan X-band measure-
ments covering the entire life history of a tornado in a supercell in Kansas in 2008,
and the complete life history of a tornado in southeastern Wyoming on June 5,
2009, during the first year of VORTEX2. This VORTEX2 tornado had dual-
Doppler collection with mobile radars and volumetric, single-Doppler coverage
with rapid update times.
Tim Samaras, an engineer, has made some remarkable in situ measurements in
tornadoes during TWISTEX, with a Turtle-like instrument, especially in 2003,
when he also recorded some breathtaking video as the tornado passed overhead.
In addition, during VORTEX2, in situ mobile mesonet observations were made
along with mobile rawinsonde observations and other probes (such as the Stick-
nets and Tornado Pods), other successors to the Turtles of the late 1980s. The
modern version of the instrumented tank proposed back in the early 1970s was
realized by the TIV (Tornado Intercept Vehicle). This instrument was highly pub-
licized by a Discovery Channel television series and has made some in situ
measurements in tornadoes. During the second year of VORTEX2, in 2010, Texas
Tech successfully obtained Ka-band Doppler radar measurements in tornadoes;
the Ka-band radar is a compromise between the high spatial resolution, narrow-
beam W-band radar, which has a severely restricted range when there is attenua-
tion by intervening heavy precipitation, and the less high spatial resolution of the
less narrow beam X-band radar which, while still adversely affected by attenuation
from heavy precipitation, is not as severely range limited.
The year after year 2 of VORTEX2, 2011, ironically was very unusual in
terms of the number of severe weather events in the U. S. A record number of
tornadoes struck the U. S. in the spring, inflicting devastating damage in cities
such as Joplin, MO (May 22), Raleigh, NC (April 16), and Tuscaloosa, Alabama
(April 27), while also striking the airport in St. Louis, Missouri (April 22) and
portions of Springfield, Massachusetts (June 1). A tornado even hit Auckland,
New Zealand on May 3. Despite our increased knowledge about tornadoes and
severe convective storms and increases in our skill in predicting and monitoring
them, over 500 people lost their lives in the U. S. as a result of tornadoes, more
than any year since 1953. The first rapid-scan (mechanically scanning, not electro-
nically scanning) polarimetric, X-band, Doppler radar, RaXpol, was used by the
author and his graduate students for the first time and scanned much of the life
history of an EF-5 tornado from relatively close range, in central Oklahoma on
May 24.
While VORTEX2, ROTATE, and the U. Mass./OU collaborative field
programs were designed mainly to study tornadoes, STEPS (Severe Thunderstorm
Electrification and Precipitation Study) in 2000, centered in northwest Kansas, was
focused on precipitation and lightning in supercells and BAMEX (Bow Echo and
MCV Experiment) in the central U. S. in 2003 was focused on severe weather-
producing features found in mesoscale convective systems.
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