A Novel Approach to Study the most Energetic Lightning on Earth Using the Pierre Auger Observatory.

The Pierre Auger Cosmic Ray Observatory has been observing Emissions of Light from Very Low frequency perturbations due to Electromagnetic pulse Sources, or elve(s), since 2005. Elves are caused by the Electromagnetic Pulse (EMP) created during the lightning strike process. When the EMP interacts with the ionosphere base (90 km altitude), a ring of fluorescence emission expands radially, faster than the speed of light. The Fluorescence Detector (FD) of the Auger Observatory records the UV photons from elves every 100 ns. An elve observation by the Auger FD is a 2D projection of the EMP internal structure.

Using the 1598 elves recorded by the Auger FD during 2014-2016, we can reconstruct fundamental parameters of elve-inducing lightning strikes. Peak current, current rise time and lightning height are key to characterize the convective thunderstorm below. The Cordoba region in Northern Argentina is known for the highest flash rate of the most extreme lightning on Earth. Global warming models predict a global increase of destructive convective thunderstorms such as the ones near Cordoba. With our elve dataset that overlaps this unique region, we can contribute to the understanding of such storms and refine current models of extreme lightning.