Abstract
Abstract. Arctic landscapes are covered in snow for at least 6 months of the year. The energy balance of the snow cover plays a key role in these environments, influencing the surface albedo, the thermal regime of the permafrost, and other factors. Our goal is to quantify all major heat fluxes above, within, and below a low-Arctic snowpack at a shrub tundra site on the east coast of Hudson Bay in eastern Canada. The study is based on observations from a flux tower that uses the eddy covariance approach and from profiles of temperature and thermal conductivity in the snow and soil. Additionally, we compared the observations with simulations produced using the Crocus snow model. We found that radiative losses due to negative longwave radiation are mostly counterbalanced by the sensible heat flux, whereas the latent heat flux is minimal. At the snow surface, the heat flux into the snow is similar in magnitude to the sensible heat flux. Because the snow cover stores very little heat, the majority of the upward heat flux in the snow is used to cool the soil. Overall, the model was able to reproduce the observed energy balance, but due to the effects of atmospheric stratification, it showed some deficiencies when simulating turbulent heat fluxes at an hourly timescale.
Highlights
The Arctic winter, characterized by low solar radiation and air temperatures below 0 ◦C, presents extreme conditions to which local populations, flora, and fauna are adapting
The energy budget can be calculated at the snow surface using a control surface approach or by considering the snowpack as a whole and relying on a control volume
The vegetation at the site consists of a mixture of lichen (Cladonia sp. mostly C. stellaris and C. rangiferina) and shrub tundra with dwarf birch (Betula glandulosa) and other shrub species (Vaccinium sp., Alnus viridis subsp. crispa and Salix planifolia) that range from 0.2 to 1 m tall in the upper part of the valley, and it turns into a forest tundra populated by black spruce (Picea mariana) towards the lower part of the valley
Summary
The Arctic winter, characterized by low solar radiation and air temperatures below 0 ◦C, presents extreme conditions to which local populations, flora, and fauna are adapting. Recent studies have shown that the warming in the Arctic is most pronounced during the cold season (Graversen et al, 2008; Boisvert and Stroeve, 2015), and winter warm spells are becoming more frequent (Graham et al, 2017). This warming, both episodic and perennial, alters the properties of seasonal snow. Since snow is a highly reflective medium with low thermal conductivity, it impacts the entire energy balance at the Earth’s surface and leads to repercussions for many fields such as hydrology, permafrost modeling, weather forecasting, and climate modeling (Meredith et al, 2019). Using the control surface approach, incoming heat fluxes at the snow surface are counterbalanced by the outgoing fluxes, such that
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