Lightning flash density in Europe based on 10 years of ATDnet data

Abstract

Abstract The first decadal lightning flash climatology for Europe is presented using ATDnet long-range lightning detection network operated by the Met Office. More than 148 million lightning flashes were detected by ATDnet in the study area between 2008 and 2017. The dataset contains up to 90% of cloud-to-ground flashes and 25% of cloud flashes in Europe during the study period. All maps were computed with a spatial resolution of 0.2°. The annual flash density was between 0.5 and 3.0 flashes per km−2 y−1 in most of Europe with a maximum of 7.8 flashes km−2 y−1 in the northeast of Italy. Most of continental Europe experienced 20–40 thunderstorm days annually but a small area on the border of Armenia and Turkey experienced up to 87.6 thunderstorm days. This number exceeds previous estimates of European maximum thunderstorm frequency. The North Atlantic Ocean had only up to 10 thunderstorm days and 0.1 flash km−2 y−1. Flash density per thunderstorm day varied from 0.1 fl km−2 in the northeast of Italy. Occasional intense storms were found to happen even in areas without regular thunderstorm activity, including the oceans to the north of the Arctic Circle. Most of the study area had a mid-latitude specific summer peak in lightning activity whereas the Mediterranean experienced an autumn maximum. From March to August, most of the lightning in Europe occurred over land whereas from September to February it was concentrated over the Mediterranean. The highest lightning frequency over land was observed during the afternoon hours and the lowest frequency at night. At sea the diurnal distribution of lightning peaked either at night or in the morning hours.