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

Abstract

Abstract. Winter near-surface temperatures have important implications for ecosystem functioning such as vegetation dynamicsand 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 difficultto estimate the spatio-temporal variability of this relationship. Here, we quantified the fine-scale variability of winternear-surface temperatures (+2 cm) and snow cover duration using a total of 441 microclimate loggers in seven study areasacross boreal and tundra landscapes during 2019–2021. We further examined the drivers behind this variation and the extentto which surface temperatures are buffered from air temperatures during winter. Our results show that while average winternear-surface temperatures stay close to 0 °C across the study domain, there are large differences in their fine-scale variabilityamong the study areas. Areas with large topographical variation, as well as areas with shallow snowpacks, showed the greatestvariation in near-surface temperatures and in the insulating effect of snow cover. In the tundra, for example, differences inminimum near-surface temperatures were close to 30 °C. In contrast, flat topography and deep snow cover lead to little spatialvariation and decoupling of the near-surface and air temperatures. Quantifying and understanding the landscape-wide variationin winter microclimates improves our ability to predict the local effects of climate change in the rapidly warming boreal andtundra regions.

Evaluating local drivers of ground surface temperature variability in coastal Labrador

“…Greater withinecotype variability was observed at the northern field site (NBH) than at the southern field site (PRH). These results are similar to those reported by Tyystjärvi et al (2023) who found that MAGST variability increased with latitude at field sites in Finland, although Odland et al (2017) did not find a similar latitudinal association in the Norwegian mountains.…”