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TitreSpatial and thermal characteristics of mountain permafrost, northwest Canada
AuteurLewkowicz, A G; Bonnaventure, P B; Smith, S L; Kuntz, Z
SourceGeografiska Annaler, Series A vol. 94, issue 2, 2012 p. 195-213,
Séries alt.Secteur des sciences de la Terre, Contribution externe 20110325
Documentpublication en série
Mediapapier; en ligne; numérique
ProvinceColombie-Britannique; Yukon
SNRC94M; 94N; 95C; 95D; 95E; 95F; 95K; 95L; 95M; 104M; 104N; 104O; 104P; 105; 106A; 106B; 106C; 106D; 114O; 114P; 115; 116A; 116B; 116C
Lat/Long OENS-141.0000 -124.0000 65.0000 59.0000
Sujetspergélisol; températures au sol; glace fossile; temperature; congélation du sol; géologie des dépôts meubles/géomorphologie; Cénozoïque; Quaternaire
Illustrationslocation maps; plots; tables
Programmepipeline nordiques, Géoscience de l'environnement
Résumé(disponible en anglais seulement)
An extensive network of monitoring stations was used to develop a mean annual air temperature map for the complex mountainous terrain in the southern Yukon and northern British Columbia, Canada (latitude 59° to 65° N). Air temperature lapse rates measured at screen height from valley bottoms up to treeline are normal in the maritime extreme southwest, normal but weak in much of the region, and inverted in the highly continental northernmost sites. Relationships between air and ground surface temperatures, expressed as freezing and thawing n-factors, vary significantly with vegetation type and hence elevational band, with the lowest values for the forested zone and the highest for non-maritime alpine tundra. Equilibrium modelling carried out for one site in the southern part of the region and one in the northern part illustrates the impacts of the differing n-factors on trends in mean ground surface temperature with elevation. Ground thermal regimes determined at borehole locations vary greatly due to these climatic controls but are also affected by substrate. Valley-bottom permafrost in the south is scattered, at temperatures just below 0°C, has a depth of zero annual amplitude of 2 - 3 m (due to latent heat effects) and may be only a few metres in thickness. Permafrost on bedrock summits is cold, has active layers >5 m thick, is >50 m thick and may be locally continuous. Given the range of air temperatures and n-factors, permafrost is possible throughout the Yukon but higher temperatures southward and stronger lapse rates mean that a lower elevational limit exists in northern British Columbia.