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Dr. Hugh J. Christian |
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Time:
Tuesday, 1 April 2014
0905 - 0925
Global Lightning Mapper |
Hugh Christian is a Principal Research Professor in the
Earth System Science Center at the University of Alabama in
Huntsville where he specializes in Atmospheric
Electricity and Lightning research. He began working on the
concept of a lightning mapper in geostationary orbit when he
first joined NASA in 1980. In 1995 he placed his first
lightning sensor, the Optical Transient Detector (OTD) in
low earth orbit and followed this with the Lightning Imaging
Sensor (LIS) in 1997 which is still in operation. He is the
Principal Investigator of both the OTD and LIS.
He teamed with Lockheed Martin in 2006, after retiring from
NASA, in order to design the Geostationary Lightning Mapper.
He continues to work with Lockheed Martin in developing of
the GLM as well as pursuing basic research in lightning
physics. |
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Abstract |
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This presentation will discuss how total lightning
observations from geostationary orbit can be used to
monitor thunderstorm development and help to identify
which specific cell out of an ensemble of cells has the
potential to become severe. In addition to identifying
potentially dangerous thunderstorm cells, space-based
lightning measurements also hold the potential for
improving severe weather warning times and reducing
false alarm rates.
Lightning is a powerful tool for remotely monitoring
thunderstorms because it is relatively easy to detect
and it provides information on physical processes that
are occurring deep in the interior of the storm. For
geostationary applications, this makes lightning
observations unique in that other sensors receive data
from primarily the top of the cloud.
Thunderstorm electrical energy is generated during ice
formation and growth and is dissipated by lightning
within minutes of its generation. As a consequence,
lightning flash rates track cloud evolution: as the
cloud intensifies, the flash rate increases, as the
cloud dissipates, the flash rate decreases. It is
precisely because electrical energy generation is so
tightly coupled latent heat production, that lightning
observations provide a powerful tool for storm
monitoring.
Lightning based algorithms that are currently be
developed for severe weather now-casting will be
discussed as well as anticipated performance. For
example the two sigma lightning jump algorithm holds
promise to improve tornado warning lead times to greater
than 20 minutes while halving the present false alarm
rates.
In addition to establishing the basis for the value of
lightning monitoring of storm development, a concept for
a simplified geostationary-based lightning mapper will
be presented. This sensor, which would be much smaller
and less expensive than the Geostationary Lightning
Mapper (GLM), could easily be flown on a commercial
communications satellite and would be ideal for
monitoring reduced special coverage regions such as the
Indian Sub-continent. |
