Assessing the power law distribution of TGFs

The times and locations of 972 TGFs detected by Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) between 4 March 2002 and 6 September 2010 were compared to lightning data for the same period. Based on a simple coincidence algorithm, 93 TGFs were uniquely matched to individual lightning discharges. The average delay between the lightning and the associated TGF was -0.77 ms, suggesting that the TGFs occurred prior to the lightning discharge. The majority of the matched lightning occurred within 500 km of the RHESSI sub-satellite point, although a few events were found at larger distances. A comparison of TGF intensity to observation angle for the matched events was found to be consistent with a power law model for the distribution of TGF intensities. Finally it was found that the matched TGFs were predominantly those of lower intensity.