Synoptic control on snow avalanche activity in central Spitsbergen

Holt Hancock,Siiri Wickström,Markus Eckerstorfer,Jordy Hendrikx

doi:10.5194/tc-15-3813-2021

Abstract

Abstract. Atmospheric circulation exerts an important control on a region's snow avalanche activity by broadly determining the mountain weather patterns that influence snowpack development and avalanche release. In central Spitsbergen, the largest island in the High Arctic Svalbard archipelago, avalanches are a common natural hazard throughout the winter months. Previous work has identified a unique snow climate reflecting the region's climatically dynamic environmental setting but has not specifically addressed the synoptic-scale control of atmospheric circulation on avalanche activity here. In this work, we investigate atmospheric circulation's control on snow avalanching in the Nordenskiöld Land region of central Spitsbergen by first constructing a four-season (2016/2017–2019/2020) regional avalanche activity record using observations available on a database used by the Norwegian Water Resources and Energy Directorate (NVE). We then analyze the synoptic atmospheric conditions on days with differing avalanche activity situations. Our results show atmospheric circulation conducive to elevated precipitation, wind speeds, and air temperatures near Svalbard are associated with increased avalanche activity in Nordenskiöld Land, but different synoptic signals exist for days characterized by dry, mixed, and wet avalanche activity. Differing upwind conditions help further explain differences in the frequency and nature of avalanche activity resulting from these various atmospheric circulation patterns. We further employ a daily atmospheric circulation calendar to help contextualize our results in the growing body of literature related to climate change in this location. This work helps expand our understanding of snow avalanches in Svalbard to a broader spatial scale and provides a basis for future work investigating the impacts of climate change on avalanche activity in Svalbard and other locations where avalanche regimes are impacted by changing climatic and synoptic conditions.

Highlights

Snow avalanches are natural hazards occurring in mountainous environments where complex interactions between the terrain, weather, and snowpack allow for masses of snow to rapidly descend steep slopes (e.g., Schweizer et al, 2003a)
We explored the relationship between atmospheric circulation patterns across a broad portion of the North Atlantic and Arctic regions and observed avalanches in Nordenskiöld Land to investigate the synoptic-scale meteorological controls on avalanche activity in central Spitsbergen
We employed crowd-sourced avalanche occurrence data available on the regObs natural hazard database from four winter seasons (2016/2017–2019/2020) to identify 632 individual avalanches occurring on 166 d, 34 of which we classified as high-activity days

Summary

Introduction

Snow avalanches are natural hazards occurring in mountainous environments where complex interactions between the terrain, weather, and snowpack allow for masses of snow to rapidly descend steep slopes (e.g., Schweizer et al, 2003a). Avalanche forecasts seek to reduce risks associated with snow avalanche hazards by predicting avalanche conditions by integrating information related to an area’s terrain, past and current meteorological conditions, and snowpack (LaChapelle, 1980; McClung, 2002b). Previous work investigating the controls on avalanching at broader, regional to sub-continental spatial scales has focused on understanding the linkages between synoptic-scale atmospheric circulation patterns and periods of increased avalanche activity H. Hancock et al.: Synoptic control on snow avalanche activity in central Spitsbergen

Results

Discussion

Conclusion