Study on multi-ELVES in the Pierre Auger Observatory

PIERRE AUGER COLLABORATION; A MARIAZZI

Berlin

Conferencia; 37th International Cosmic Ray Conference (ICRC2021); 2021

Since 2013, the four sites of the Fluorescence Detector (FD) of the Pierre Auger Observatoryrecord ELVES with a dedicated trigger. These UV light emissions are correlated to distantlightning strikes. The length of recorded traces has been increased from 100 휇s (2013), to 300 휇s(2014-16), to 900 휇s (2017-present), to progressively extend the observation of the light emissiontowards the vertical of the causative lightning and beyond. A large fraction of the observed eventsshows double ELVES within the time window, and, in some cases, even more complex structuresare observed. The nature of the multi-ELVES is not completely understood but may be relatedto the different types of lightning in which they are originated. For example, it is known thatNarrow Bipolar Events can produce double ELVES, and Energetic In-cloud Pulses, occurringbetween the main negative and upper positive charge layer of clouds, can induce double and evenquadruple ELVES in the ionosphere. This report shows the seasonal and daily dependence of thetime gap, amplitude ratio, and correlation between the pulse widths of the peaks in a sample of1000+ multi-ELVES events recorded during the period 2014-20. The events have been comparedwith data from other satellite and ground-based sensing devices to study the correlation of theirproperties with lightning observables such as altitude and polarity