Enhanced detection of terrestrial gamma-ray flashes by AGILE

TL;DR

Modifying AGILE satellite's onboard software to disable the anticoincidence veto significantly increased terrestrial gamma-ray flash detection rates, enabling better correlation with lightning and atmospheric phenomena.

Contribution

This study demonstrates that disabling the anticoincidence veto on AGILE's minicalorimeter greatly enhances TGF detection, providing unprecedented detection rates and spatial-temporal resolution.

Findings

TGF detection rate increased by an order of magnitude.

Most new TGFs are short-duration (< 100 μs).

Many TGFs are associated with lightning sferics detected by WWLLN.

Abstract

At the end of March 2015 the onboard software configuration of the AGILE satellite was modified in order to disable the veto signal of the anticoincidence shield for the minicalorimeter instrument. The motivation for such a change was the understanding that the dead time induced by the anticoincidence prevented the detection of a large fraction of Terrestrial Gamma-Ray Flashes (TGFs). The configuration change was highly successful resulting in an increase of one order of magnitude in TGF detection rate. As expected, the largest fraction of the new events has short duration ($< 100 \mathrm {\mu s}$), and part of them has simultaneous association with lightning sferics detected by the World Wide Lightning Location Network (WWLLN). The new configuration provides the largest TGF detection rate surface density (TGFs/$\mathrm{km^2}$/year) to date, opening prospects for improved correlation studies with lightning and atmospheric parameters on short spatial and temporal scales along the equatorial region.