Terrestrial gamma ray flashes and lightning discharges

Abstract

Analysis of ELF/VLF broadband data from Palmer Station, Antarctica indicates that 76% Terrestrial Gammaray Flashes (TGFs) detected on the RHESSI spacecraft occur in association with lightning-generated radio atmospherics arriving from near the footprint of RHESSI and within a few ms of the TGF. The remaining TGFs are not associated with any radio atmospheric, thus by implication CG lightning. The peak currents of TGF-associated lightning discharges are often among the most intense from a given storm, with the degree of this association apparently varying between oceanic and land regions. The time-integrated ELF energy of the associated sferics (and thus the lightning charge moment) exhibit much less tendency to be large. Statistical analysis of the spread in arrival time suggests a ∼2 ms variance due to factors other than geometry and measurement error. Copyright 2006 by the American Geophysical Union.