HR: 17:00h
AN: AE14A-05    [Abstracts]
TI: Monte Carlo simulations of terrestrial gamma-ray flashes
AU: * Dwyer, J R
EM: jdwyer@fit.edu
AF: Florida Institute of Technology, Department of Physics and Space Sciences, 150 W. University Blvd, Melbourne, FL 32901 United States
AU: Smith, D M
EM: dsmith@scipp.ucsc.edu
AF: University of California, Physics Department and Santa Cruz Institute for Particle Physics, Santa Cruz, CA 95064 United States
AB: We have performed detailed Monte Carlo simulations of the runaway breakdown of air to calculate the spectra of terrestrial gamma-ray flashes (TGFs), which are then compared with RHESSI and CGRO/BATSE observations. It is found that the recent RHESSI spectrum is not consistent with a source altitude above 24 km but can be well fit by a source in the range of 15 - 21 km, depending upon the electric field geometry of the source. Because 24 km is lower than typical minimum sprite altitudes, this result implies that the source of these TGFs is not sprites, as has long been assumed. Furthermore, because 15 km is not unusual for the tops of thunderstorms, especially at low latitudes where the tropopause is higher, the RHESSI data implies that thunderstorms could in fact be the source of these TGFs. On the other hand, the soft energy spectrum seen in some BATSE TGFs is inconsistent with such large atmospheric depths. Because the selection criteria for the RHESSI TGFs and BATSE TGFs were different, it is possible that there may exist two distinct sources of TGFs, with altitudes below 21 km and above 30 km.
DE: 3300 ATMOSPHERIC PROCESSES
DE: 3304 Atmospheric electricity
DE: 3324 Lightning
DE: 3367 Theoretical modeling
SC: Atmospheric and Space Electricity [AE]
MN: Fall Meeting 2005