Location prediction of electron TGFs

Abstract

Terrestrial Gamma-ray Flashes (TGFs) are brief pulses of energetic radiation that correlate with thunderstorms and lightning. Most TGFs are observed as gamma-ray pulses; less frequently they can be observed as electrons and positrons that travel along the geomagnetic field line from the source to the detector. In this paper we predict where electron TGFs should be observed by tracing geomagnetic field lines from likely TGF sources and determining the intersections with satellite orbits. TGF source locations are based upon lightning maps by the Lightning Imaging Sensor (LIS) and the Optical Transient Detector (OTD). Predictions are made both for existing spacecraft with instruments observing TGFs and for other orbits. We compare the predictions to the locations of TGFs that have been observed as electron TGFs. 12 of the 13 known electron TGFs are within the predicted high-rate regions. Based on the predicted location maps of electron TGFs, we find that electron TGFs should sometimes be observed above areas with low lightning activity and that electron TGFs are best observed at low altitudes (below approximately 1000km). Copyright 2012 by the American Geophysical Union.