Spatiotemporal variations and climatic drivers of lightning activities across pan-Arctic regions during 2010-2024

Lightning activities could influence regional air quality and terrestrial ecosystems, through physicochemical processes such as lightning-generated nitrogen oxides and wildfire risks. However, characteristics and causes of lightning activities across high-latitudes such as pan-Arctic regions are still unclear. Here, we explore spatiotemporal variations and climatic drivers of lightning stroke density (LSD) across pan-Arctic regions (45°N-90°N) during 2010-2024, based on global latest lightning datasets. Results showed that LSD is up to 9.29 strokes 100 km-2 year-1 over pan-Arctic regions during 2010-2024, with positive trends of 0.556 strokes 100 km-2 year-1 for land girds. Regionally, LSD shows significant positive linear trends in North America (NAM), central Europe (CEU) and western Russia (WRU), high up to 2.159 strokes 100 km-2 year-1, 3.612 strokes 100 km-2 year-1, and 2.071 strokes 100 km-2 year-1, respectively. However, LSD decreases significantly by -2.042 strokes 100 km-2 year-1 in northern China (NCH). The possible climatic causes of LSD trends are examined across four regions through multiple linear regression and random forest models. Increasing sea surface temperature dominates positive LSD trends up to 1.125 strokes 100 km-2 year-1 and 2.119 strokes 100 km-2 year-1 over NAM and CEU, accounting for 52% and 59% of observed trends. Increased surface air temperature and reduced aerosols control jointly increasing LSD trends over WRU, up to 1.280 strokes 100 km-2 year-1 and 1.112 strokes 100 km-2 year-1 respectively. Negative LSD trends in NCH are mainly related to the increases of local wind shear, resulting in a decline of -0.934 strokes 100 km-2 year-1 in LSD trends. Moreover, random forest models as cross-validations also reveal similar climatic causes over these regions. Our findings highlight that lightning activities show increasing trends over high-latitude regions in recent decades, and suggest us need to fully consider impacts of climate change on future lightning activities under various emission scenarios.