Measurements and implications of the relationship between lightning and terrestrial gamma ray flashes

We report observations and analysis of 30 kHz radio emissions (sferics) from lightning discharges associated with 26 terrestrial gamma ray flashes (TGFs) recorded by the RHESSI satellite over the Caribbean and Americas, between 1500 and 4000 km away from the magnetic field sensors located at Duke University. Thirteen of the TGFs are found to occur within - 3/+ 1 ms of lightning discharges of positive polarity from the direction of the RHESSI subsatellite point, strongly indicating that the TGFs are linked to these discharges. The event timing and sferic direction finding reveals that the discharges occur within a ∼ 300 km radius circle around the RHESSI subsatellite point. Although the positive polarity of all 13 discharges is consistent with runaway breakdown, the lightning charge moment changes are approximately two orders of magnitude smaller than present high altitude runaway breakdown theory predicts. Implications of these measurements are discussed.