Observing Snow from the Sky: Spatial and Temporal Variations of Tundra Snow Depth, Covered Area and Snow-Water Equivalent using Unmanned Aerial Systems (UAS)

Arctic tundra environments are characterized by a spatially heterogeneous end-of-winter snow distribution resulting in large spatial variations in snow depth, density and water equivalent. Understanding the distribution of snow across tundra environments is important as the snow accumulation in the Canadian Western Arctic accounts for over half of the annual precipitation. Currently, our ability to accurately measure snow using in-situ and remote sensing techniques has proven difficult where traditional methods often fail to accurately represent small-scale variations in snow cover at catchment scales. Furthermore, the accumulation patterns at landscape scales are poorly documented resulting from technical and environmental limitations. In this study we document spatial variations in snow accumulation and ablation across a shrub-tundra catchment as part of the TVCSnow campaign from Trail Valley Creek, NWT. We applied Structure-from-Motion photogrammetry using a fixed-wing Unmanned Aerial System (UAS) resulting in high-resolution snow depth mapping (1 meter) at key periods of snow accumulation and throughout the spring snowmelt period. In combination with UAS aerial surveys, snow depth and water equivalent measurements were recorded across the winter accumulation period resulting in a detailed documentation of snow accumulation and ablation for various dominant land cover types. The ability to capture high-resolution spatio-temporal changes to tundra snow cover furthers our understanding of the relative importance of various land cover types on winter snow accumulation and ablation which has strong implications on the hydrological system during the spring freshet.