Interannual variability of soil thermal conductivity and moisture on the Abernethy Flats (James Ross Island) during thawing seasons 2015–2023

• Published in: Catena (Giessen) 2024-01, Vol.234, p.107640, Article 107640
• Main Authors: Kňažková, Michaela, Hrbáček, Filip
• Format: Article
• Language: English
• Subjects: air; Antarctic region; Antarctica; catenas; permafrost; semiarid zones; soil heat flux; soil profiles; soil water; temperature; thermal conductivity; volumetric water content; weather
• ISSN: 0341-8162
• DOI: 10.1016/j.catena.2023.107640

The knowledge of soil thermal properties is important for determining how a soil will behave under changing climate conditions, especially in the sensitive environment of permafrost affected soils. This paper represents the first complex study of the interplay between the different parameters affecting soil thermal conductivity of soils in Antarctica. Antarctic Peninsula is currently the most rapidly warming region of the whole Antarctica, with predictions of this warming to continue in the upcoming decades. This study focuses on James Ross Island, where the Abernethy Flats automatic weather station is located in a lowland area with semi-arid climate. Air and ground temperature, soil heat flux and soil moisture during the thawing season were monitored on this site from 2015 to 2023. Moreover, two approaches to determining soil thermal conductivity were compared – laboratory measurements and calculation from field data. During this period, mean annual temperatures have increased dramatically for both air (from −6.9 °C in 2015/2016 to −3.8 °C in 2022/2023) and ground (from −6.5 °C to −3.2 °C), same as active layer thickness (from 68 cm to 95 cm). Average soil thermal conductivity for the thawing period reached values between 0.49 and 0.74 W/m.K⁻¹ based on field data. Statistically significant relationships were found between the seasonal means of volumetric water content and several other parameters – soil thermal conductivity (r = 0.91), thawing degree days (r = −0.87) and active layer thickness (r = −0.88). Although wetter soils generally have a higher conductivity, the increase in temperature exhibits a much stronger control over the active layer thickening, also contributing to the overall drying of the upper part of the soil profile.