Specific Ground Truth Data Analysis of Lightning Discharges in Austria

Abstract

This paper presents an analysis of specific parameters of lightning discharges in the field of lightning research and observation in the Austrian Alps run by Graz University of Technology in correlation with detections from the Austrian Lightning Location System (LLS). Atmospheric discharges are observed at 21 different measurement locations in Austria by using a video and field recording system. This system consists of a high speed video camera (2000 frames per second) and a flat plate antenna to record the electric field. The recorded data can be used to better understand the atmospheric discharges, especially in the alpine area. The ground truth data set of the measurement periods 2015, 2017 and 2018 have been correlated with LLS data to complete the data set. For this analysis the multiplicity of VFRS and LLS data have been compared. In addition, analyses regarding ground strike points (GSP) per flash and distances between GSPs of flashes have been carried out. The mean multiplicity of the analyzed ground truth data exhibited a lower value compared to multiplicities from other countries available in the literature, but similar ones determined by former studies from Austria. Data of GSP per flashes showed similar values like studies from Brazil and a first data set from Arizona but higher values compared to analyses of data from France and a second data set from Arizona. Calculations of distances between the first GSP of a flash to the other GSPs of the same flash showed a median of 1.4 km, an arithmetic mean of 1.6 km and a geometric mean of 1.2 km. The maximum determined distance between two GSPs was 6.9 km.