How snow, vegetation and soil properties influence soil temperatures in a permafrost environment (Trail Valley Creek, Western Canadian Arctic)

Warming ground temperatures in the Arctic raise the need to forecast permafrost thaw. Seasonal snow cover is a crucial factor for ground temperatures as it can have a warming or cooling effect on the underlying soil, depending on snow cover timing and its physical properties. Vegetation and topography modulate snow distribution and affect the snow thermal insulation. However, the formation processes and resulting properties of Arctic snowpacks are difficult to represent in snow models and in-situ data is sparse. Further understanding of the interactions between snow, vegetation and permafrost and the deduction of empirical relationships could support the parametrization of snow in permafrost modeling.

We study how the ground thermal regime is influenced by the interplay of snow, vegetation, topography and climatic conditions. In particular, we evaluate the effect of snow density variation on the ground thermal regime. We present a novel dataset that combines air, surface and soil temperature, as well as soil moisture time series recorded from September 2024 to August 2025 with end-of-season snow depth distribution and high-resolution vertical snow density profiles. Temperatures and soil moisture were monitored using 60 TOMST TMS-4 loggers, distributed across different vegetation types and topographic features in the taiga-tundra ecotone (Trail Valley Creek, Northwest Territories, Canada). Snow density profiles were measured in March 2025 next to the TOMST loggers using a SnowMicroPen.

Our data shows several characteristic snowpack types which do not only differ in depth but also have a different layering structure. Low density snowpacks with high depth hoar fractions are most prominent in forested areas that are shielded from the wind, whereas leeward slopes can accumulate thick, high-density wind slab, regardless of vegetation. While snow depth is clearly one of the major drivers of soil temperature, the role of snow density is more complex.

Categorization of different tundra vegetation types with characteristic snow conditions and specific impact on permafrost vulnerability helps to refine permafrost models and constrain predictions of permafrost thaw.