HR: 0800h
AN: AE31A-0028    [Abstracts]
TI: Radiation Patterns of Lightning
AU: * Harlin, J D
EM: harlin@lanl.gov
AF: Los Alamos National Laboratory ISR-2, Space and Remote Sensing Group, Mailstop D436, Los Alamos, NM 87545, United States
AU: Krehbiel, P R
EM: krehbiel@ibis.nmt.edu
AF: New Mexico Institute of Mining and Technology, 801 Leroy Pl., Socorro, NM 87801, United States
AU: Shao, X
EM: xshao@lanl.gov
AF: Los Alamos National Laboratory ISR-2, Space and Remote Sensing Group, Mailstop D436, Los Alamos, NM 87545, United States
AU: Thomas, R J
EM: thomas@nmt.edu
AF: New Mexico Institute of Mining and Technology, 801 Leroy Pl., Socorro, NM 87801, United States
AB: New Mexico Tech's Lightning Mapping Array (LMA) uses time-of-arrival measurements at a network of stations to accurately locate VHF radiation sources in three spatial dimensions and time. The peak power values are also measured at each station but have not been fully utilized. Currently the source power calculations assume an isotropic source and an isotropic receiver gain pattern. The event source power is approximated by the median value of the contributing stations. The receiver gain pattern of individual LMA stations were empirically determined, and are in agreement with analytical formulations. Incorporating the receiver gain pattern improved the source power calculation, reducing the standard deviation of the individual station powers to about 1.5 dB. Using the corrected power calculations, three 10-minute time intervals comprising of 7.5 million sources, were used to look for source radiation patterns having 15 dB nulls relative to the median source power. Of the 167,720 candidate events 244 had an identifiable radiation source pattern. These patterns ranged from simple dipole patterns to relativistically beamed patterns with a velocity 99 percent the speed of light. It is expected that many more sources had nulls that were not as strong or that were not directed at a station.
DE: 3304 Atmospheric electricity
DE: 3324 Lightning
SC: Atmospheric and Space Electricity [AE]
MN: 2007 Fall Meeting