Historical Patterns of Snow Drought in Fennoscandia: 1980-2022

Snow drought is characterized by an abnormally low snowpack, resulting generally from reduced precipitation, warmer surface air temperature (SAT), or a combination of both. However, there is still a limited understanding of how snow drought patterns change across space and time. Hence, this study investigates the influence of precipitation and SAT on the spatio-temporal patterns of snow droughts in Fennoscandia during 1980-2022. In general, the results show strong spatial variations in dry (reduced precipitation) and warm (elevated SAT) snow drought types across Fennoscandia over time. Dry snow droughts were more frequent in northern and mountainous parts of Fennoscandia, indicating that precipitation deficits are the primary driver under persistent cold conditions. In contrast, warm snow droughts were more spatially extensive, affecting both northern and southern regions, and showing considerably higher frequencies in coastal zones and lower-latitude areas. This sheds particular light on the increasing occurrence of SAT-driven snow droughts across Fennoscandia. These findings indicate a transition from precipitation-driven snow droughts in high-latitude regions to SAT-driven events in southern and maritime areas in response to global warming and climate change. Accordingly, this study lays a solid foundation for developing climate-adaptive water resources management strategies in Fennoscandia, where snowpack plays a crucial role in water security and regional sustainable development.