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Lightning at the tundra/Boreal forest interface: A study of northern Manitoba and southern Kivalliq from 1998-2023

Trippier, Shayla1; Crawford, Alex1; Hanesiak, John1; Lukovich, Jennifer1; Stroeve, Julienne1

Published Jul 07, 2026 on Dryad. https://doi.org/10.5061/dryad.12jm63zbq

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Abstract

Cloud-to-ground (CG) lightning frequency is projected to increase under future warming scenarios in Canada’s boreal forest. In this study, we examine historical (1998-2023) CG lightning flash trends along the interface of boreal forest and Arctic tundra (encompassing northern Manitoba and the southern Kivalliq Region of Nunavut). Using the Canadian Lightning Detection Network, we assess whether projected trends in lightning flash density are already discernable, how other lightning characteristics (such as polarity and intensity of current) are changing, and, using the ERA5 atmospheric reanalysis, whether changing lightning characteristics are explainable by associated thunderstorm environments. We find that positively charged CG lightning (+CG) is increasing throughout the study area, although negatively charged CG lightning (-CG) remains the dominant lightning polarity. Trends in other lightning characteristics demonstrate regional variations and suggest a strong role for internal variability. Southern Kivalliq stands out as the region exhibiting the greatest relative increases in lightning frequency and intensity. Northern Manitoba exhibits an overall decline in lightning frequency (due to fewer -CG flashes), although the -CG current strength is increasing. The shift toward relatively more +CG events aligns with changes in the thunderstorm environment in southern Kivalliq. Elsewhere, driving mechanisms are either weak or counteract each other.