Comment on egusphere-2023-576

Abstract

<strong class="journal-contentHeaderColor">Abstract.</strong> Winter near-surface temperatures have important implications for ecosystem functioning such as vegetation dynamics<br />and carbon cycling. In cold environments, seasonal snow cover can exert a strong control on the surface temperatures.<br />However, the lack of in situ measurements of both snow cover and surface temperatures over high latitudes has made it difficult<br />to estimate the spatio-temporal variability of this relationship. Here, we quantified the fine-scale variability of winter<br />near-surface temperatures (+2 cm) and snow cover duration using a total of 441 microclimate loggers in seven study areas<br />across boreal and tundra landscapes during 2019&ndash;2021. We further examined the drivers behind this variation and the extent<br />to which surface temperatures are buffered from air temperatures during winter. Our results show that while average winter<br />near-surface temperatures stay close to 0 <span class="ILfuVd NA6bn" lang="en"><span class="hgKElc"><strong>&deg;</strong></span></span>C across the study domain, there are large differences in their fine-scale variability<br />among the study areas. Areas with large topographical variation, as well as areas with shallow snowpacks, showed the greatest<br />variation in near-surface temperatures and in the insulating effect of snow cover. In the tundra, for example, differences in<br />minimum near-surface temperatures were close to 30 <span class="ILfuVd NA6bn" lang="en"><span class="hgKElc"><strong>&deg;</strong></span></span>C. In contrast, flat topography and deep snow cover lead to little spatial<br />variation and decoupling of the near-surface and air temperatures. Quantifying and understanding the landscape-wide variation<br />in winter microclimates improves our ability to predict the local effects of climate change in the rapidly warming boreal and<br />tundra regions.