[meteorite-list] DOPPLER WEATHER RADAR OBSERVATIONS OF THE 14 APRIL 2010 SOUTHWEST WISCONSIN METEORITE FALL.

From: Shawn Alan <photophlow_at_meteoritecentral.com>
Date: Wed, 4 Aug 2010 16:12:36 -0700 (PDT)
Message-ID: <246238.10986.qm_at_web35407.mail.mud.yahoo.com>

Hello Listers,
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Its been a few months and still no word with the Livingston meteorite fall, however, I found this great abstract from the 73rd Annual Meeting of the Meteoritical Society. What I read about the abstract that was cool about the WI fall is that this is the first time a meteorite fall has been detected on radar while still optically bright above 28km local terrain. This detection might give scientists a better understanding the factors that play on the role of how meteors burn up in the atmosphere??
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73rd Annual Meteoritical Society Meeting (2010)
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DOPPLER WEATHER RADAR OBSERVATIONS OF THE
14 APRIL 2010 SOUTHWEST WISCONSIN METEORITE
FALL
Marc D. Fries1 and Jeffrey A. Fries2. 1Jet Propulsion Laboratory,
4800 Oak Grove Dr., Pasadena CA 91001 E-mail:
Marc.D.Fries at jpl.nasa.gov. 2Air Force Weather Agency/1st
Weather Group, Offutt AFB, Omaha, NE 68113.
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Introduction: Shortly after 10pm local time on 14 April
2010, residents of parts of Wisconsin, Iowa, Minnesota and Illinois
were treated to an extraordinarily bright fireball traveling
approximately NW to SE along a long, flat trajectory. The fireball
followed a ground track that lies west of Madison, WI and
north of Davenport, IA and was punctuated by a series of bright
explosions at its terminus. This fall is unnamed at the time of this
writing but was located near the towns of Livingston, Mineral
Point and Mifflin, WI. At this time, approximately 2-3 kg of
meteorites have been recovered from the strewn field and reports
of new finds are still emerging.
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This meteorite fall was recorded by four different Doppler
weather radars of the National Weather Service's NEXRAD national
radar network. In terms of detection of a fall using weather
radar, this fall is remarkable in that it is the first fall detected
while still optically bright (a ?Type A? event [1]) at an altitude of
28 km above local terrain. Radar data collected from this fall was
widely disseminated on a National Weather Service web site and
used by meteorite collectors to rapidly locate meteorites. This
makes the WI fall the fourth meteorite fall to be detected by
weather radar at the time of the fall, after the West, TX (?Ash
Creek?), Grimsby, Ontario, and Lorton, VA falls [2].
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Description: The SW Wisconsin fall was recorded by the
KDMX, KARX, KMKX and KDVN radars which bracket the
fall location. By coincidence, the KARX radar was only ~110 km
distant and operating in high-speed VCP 12 mode, scanning
through seventeen 360 degree sweeps every 4.5 minutes at elevations
up to 19.5 degrees. KARX records a breakup event at a
remarkable 28 km above local ground level while the fireball was
still optically bright and roughly 25 km laterally distant from the
approximate center of the strewn field as it is currently known.
This event was recorded at 0306:09 UTC. An additional radar
return is recorded at 27 km altitude by the KDMX radar. The
next appearance of falling debris occurs at about 8 km altitude
over the local terrain, detected in multiple sweeps from the data
set begun at 0306:46 UTC by the KARX radar. Multiple radars
then record a very large spread of falling debris below 2.5 km
altitude, covering an area in excess of 20 km long along the long
axis of the strewn field.
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A radiosonde balloon launched from Davenport, IA at midnight
UTC, 14-15 Apr (three hours removed from the fall) reveals
that local winds were generally light and tend to blow from
the southwest all the way up to 30 km altitude. Overall, this fall
appears to be the result of multiple detonations of a bolide at and
below 28 km altitude. The resulting multiple debris clouds were
only mildly size-sorted by prevailing winds with smaller masses
deflected towards the NE. The resulting strewn field appears to
cover a large area with various meteorite sizes interspersed along
the length of the field.
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References: [1] Fries M. and Fries J., 2010. Abstract #1179.
41th Lunar and Planetary Science Conference. [2] Corrigan C. et
al, (this volume) Meteoritical Society Conference 2010.
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http://www.lpi.usra.edu/meetings/metsoc2010/pdf/5365.pdf
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Shawn Alan
IMCA 1633
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Received on Wed 04 Aug 2010 07:12:36 PM PDT