Space-Based Identification and Meteorological Analysis of Lightning with Continuing Currents from the Meteosat Lightning Imager

Most lightning currents last only a few hundred microseconds. However, in certain cases, currents can persist for several hundred milliseconds, producing what are known as continuing currents. These continuing currents can be particularly hazardous due to their ability to transfer large amounts of charge. They may pose risks such as igniting wildfires and causing serious damage to infrastructure, including wind turbines. Although there are indications that these currents are more common in winter and over the ocean and coastal regions, the meteorological mechanisms driving their formation remain largely unexplored, highlighting a gap in our understanding of these potentially hazardous events. With the advent of the third-generation Meteosat Lightning Imager (LI), high-resolution continuous lightning observations over a vast domain encompassing all of Europe and Africa have become available. This instrument not only allows to detect continuing currents through the persistence of an optical signal across multiple consecutive time frames within the same flash, but also to investigate their properties, such as their spatial extent and duration. This study aims to (1) map the spatio-temporal distribution of continuing currents over both continental and oceanic regions and (2) characterize their individual properties such as their areal extents and duration and the prevailing synoptic conditions that might influence their development.Our analysis is based on one year of Meteosat LI data, complemented by ERA5 reanalysis to capture synoptic and mesoscale meteorological conditions at hourly resolution. We employ a combination of exploratory and statistical data analysis as well as modern machine learning techniques to gain a deeper understanding of conditions that influence the development, areal extent, and duration of continuing currents in lightning.