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Article Dans Une Revue Permafrost and Periglacial Processes Année : 2023

Fine‐scale environment control on ground surface temperature and thaw depth in a High Arctic tundra landscape

Hadi Mohammadzadeh Khani
Christophe Kinnard
  • Fonction : Auteur
Esther Lévesque
  • Fonction : Auteur

Résumé

Surface conditions are known to mediate the impacts of climate warming on permafrost. This calls for a better understanding of the environmental conditions that control the thermal regime and the depth of the active layer, especially within heterogeneous tundra landscapes. This study analyzed the spatial relationships between thaw depths, ground surface temperature (GST), and environmental conditions in a High Arctic tundra environment at Bylot Island, Nunavut, Canada. Measurements were distributed within the two dominant landforms, namely earth hummocks and low-center polygons, and across a topographic gradient. Our results revealed that GST and thaw depth were highly heterogeneous, varying by up to 3.7 & DEG;C and by more than 20 cm over short distances (<1 m) within periglacial landforms. This microscale variability sometimes surpassed the variability at the hillslope scale, especially in summer. Late-winter snowpack thickness was found to be the prime control on the spatial variability in winter soil temperatures due to the highly heterogeneous snow cover induced by blowing snow, and this thermal effect carried over into summer. However, microtopography was the predominant driver of the spatial variability in summer GST, followed by altitude and moss thickness. In contrast, the spatial variability in thaw depth was influenced predominantly by variations in moss thickness. Hence, summer microclimate conditions dominated active layer development, but a thicker snowpack favored soil cooling in the following summer, due to the later disappearance of snow cover. These results enhance our understanding of High Arctic tundra environments and highlight the complexity of considering surface feedback effects in future projections of permafrost states within heterogeneous tundra landscapes.

Domaines

Géomorphologie
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Dates et versions

hal-04171883 , version 1 (12-08-2023)

Licence

Paternité - Pas d'utilisation commerciale

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Hadi Mohammadzadeh Khani, Christophe Kinnard, Simon Gascoin, Esther Lévesque. Fine‐scale environment control on ground surface temperature and thaw depth in a High Arctic tundra landscape. Permafrost and Periglacial Processes, 2023, 34 (4), pp.467-480. ⟨10.1002/ppp.2203⟩. ⟨hal-04171883⟩
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