Preprints
https://doi.org/10.5194/egusphere-2023-576
https://doi.org/10.5194/egusphere-2023-576
19 Apr 2023
 | 19 Apr 2023
Status: this preprint is open for discussion.

Variability and drivers of winter near-surface temperatures over boreal and tundra landscapes

Vilna Aleksandra Tyystjärvi, Pekka Niittynen, Julia Kemppinen, Miska Luoto, Tuuli Rissanen, and Juha Aalto

Abstract. Winter near-surface temperatures have important implications for ecosystem functioning such as vegetation dynamics
and carbon cycling. In cold environments, seasonal snow cover can exert a strong control on the surface temperatures.
However, the lack of in situ measurements of both snow cover and surface temperatures over high latitudes has made it difficult
to estimate the spatio-temporal variability of this relationship. Here, we quantified the fine-scale variability of winter
near-surface temperatures (+2 cm) and snow cover duration using a total of 441 microclimate loggers in seven study areas
across boreal and tundra landscapes during 2019–2021. We further examined the drivers behind this variation and the extent
to which surface temperatures are buffered from air temperatures during winter. Our results show that while average winter
near-surface temperatures stay close to 0 °C across the study domain, there are large differences in their fine-scale variability
among the study areas. Areas with large topographical variation, as well as areas with shallow snowpacks, showed the greatest
variation in near-surface temperatures and in the insulating effect of snow cover. In the tundra, for example, differences in
minimum near-surface temperatures were close to 30 °C. In contrast, flat topography and deep snow cover lead to little spatial
variation and decoupling of the near-surface and air temperatures. Quantifying and understanding the landscape-wide variation
in winter microclimates improves our ability to predict the local effects of climate change in the rapidly warming boreal and
tundra regions.

Vilna Aleksandra Tyystjärvi et al.

Status: open (until 14 Jun 2023)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-576', Jonathan von Oppen, 08 May 2023 reply
  • RC2: 'Comment on egusphere-2023-576', Anonymous Referee #2, 23 May 2023 reply

Vilna Aleksandra Tyystjärvi et al.

Vilna Aleksandra Tyystjärvi et al.

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Short summary
At high latitudes, winter ground surface temperatures are strongly controlled by seasonal snow cover and its spatial variation. Here, we measured surface temperatures and snow cover duration in 441 study sites in tundra and boreal regions. Our results show large variations in how much surface temperatures in winter vary depending on the landscape and its impact on snow cover. These results emphasize the importance of understanding microclimates and their drivers under changing winter conditions.