Evolution and location of lightning events that cause terrestrial gamma ray flashes (TGFs)
Abstract
TGFs often occur during the initial breakdown (IB) stage of intracloud lightning flashes; in particular, they seem to be related to the bipolar IB pulses seen by E-change sensors. Each IB pulse usually has 1-3 fast (2-5 μs) unipolar pulses "superimposed on the initial half cycle" of a slower (~40 μs) bipolar pulse [Weidman and Krider, JGR 1979]. During the summer of 2011 we collected lightning E-change data at 10 sites covering an area of about 70 km × 100 km at the NASA/Kennedy Space Center (KSC). We also use ELF and LF data recorded at Duke University to identify lightning flashes in the KSC area that exhibit TGF-like characteristics. By using a time-of-arrival technique with our E-change data, preliminary results indicate that the successive unipolar pulses in an IB bipolar pulse are located a few hundred meters higher in altitude than the previous unipolar pulse. The E-change data during the initial half cycle of the bipolar pulse are consistent with propagation of a negative streamer upward. We will present these data and discuss ways in which the events might produce gamma rays.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFMAE32A..01M
- Keywords:
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- 3304 ATMOSPHERIC PROCESSES / Atmospheric electricity;
- 3324 ATMOSPHERIC PROCESSES / Lightning