Estimation of Return-Stroke Peak Current of Lightning Strokes Registered by WWLLN: a Case Study

Abstract

Forest fire danger predicting models should have information about the return-stroke peak current of lightning strokes. The purpose of this work is to obtain statistical characteristics of the return-stroke peak current of lightning strokes recorded by WWLLN in the Republic of Buryatia (Russian Federation). The Republic of Buryatia has a mountainous relief. Orography influences the physical conditions for the formation of thunderclouds. The originality of the research is determined by the analysis of the distributions of the return-stroke peak current for lightning discharges over different altitude zones of the Buryatia. Similar studies have been carried out, for example, for the territories of the North Caucasus, Germany, and the USA. Digital elevation model SRTMGL3 and free geoinformation software QGIS and GRASS have been used for statistical and spatial analysis. The calculation of the statistical characteristics and the construction of distributions have been performed for 171,900 lightning discharges registered by WWLLN. The average current has been ~ 69 kA, the median has been ~ 43 kA, with an average power error of 9%. For 84% of lightning discharges, the current does not exceed 100 kA. An increase in the current of lightning discharges with an increase in altitude above sea level has been noted. The average amperage and the median, are ~ 57 kA and ~ 39 kA for low mountains (less than 1000 m), ~ 70 kA and ~ 43 kA for middle mountains (from 1000 to 2000 m), and ~ 100 kA and ~ 56 kA for high mountains (more than 2000 m), respectively. The results obtained can be used to predict and assess the forest fire danger.