Daily-Resolved Lightning Climatology of the Eastern Alpine Region at the Kilometer Scale

TL;DR

This study develops a high-resolution daily lightning occurrence climatology for the eastern Alps using generalized additive models, revealing seasonal, topographical, and regional patterns of lightning activity.

Contribution

It introduces a novel 1 km² resolution lightning climatology for the eastern Alps, integrating terrain and seasonal effects with GAMs for detailed spatial-temporal analysis.

Findings

Lightning probability is less than 1% daily, increasing in spring.

Higher lightning likelihood at jagged terrains and lower elevations during snow cover.

Seasonal regional shifts in lightning patterns observed.

Abstract

Lightning flashes are rare albeit hazardous events. Despite this scarcity, generalized additive models (GAMs) succeed in producing a climatology of lightning occurrence for the eastern Alps and surrounding lowlands at an unprecedented resolution of 1\,km$^2$ for each day of April through September with data from the ALDIS lightning location system. The GAM adds the effects of seasonality, jaggedness of the terrain, and seasonally varying effects of elevation and region, thus combining information from analysis cells sharing similar characteristics. The probability of a cloud-to-ground discharge over 1\,km$^2$ on a given day is typically less than 1\,\% with a rapid increase in spring, followed by a plateau and a gentler tapering-off in fall. Probabilities early are lower at high elevations but increase once their snow cover is gone. Regional patterns of lightning also vary with season with an overall southward shift later in the year but more complex details. Grid cells with jagged topography have a higher probability of lightning.