Relation between mean annual air and ground temperatures in the permafrost region of Canada

• Main Author: Brown, R. J. E.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Building Research Advisory Board at Purdue University 1963
• Subjects: permafrost; pergélisol; soils; sol (terre); temperature; température; air; atmospheric temperature; température atmosphérique; Alta; Canada; Keg River
• Online Access: https://nrc-publications.canada.ca/eng/view/ft/?id=364bd45f-3fc7-41e1-83b0-1c5f45f4a213; https://nrc-publications.canada.ca/eng/view/object/?id=364bd45f-3fc7-41e1-83b0-1c5f45f4a213; https://nrc-publications.canada.ca/fra/voir/objet/?id=364bd45f-3fc7-41e1-83b0-1c5f45f4a213

Climate is basic to permafrost formation and is a most important factor influencing its existence. Fluctuations in the southern boundary of permafrost are generally within the confines of the 25 and 30 degree F mean annual air temperature isotherms across Canada. Local variations are influenced by microclimatic and terrain features. In permafrost the temperatures decrease steadily from the ground surface to a depth of about 50-100 ft. but below this the temperature increases steadily under the influence of the heat from the earth's interior. Ground temperatures in permafrost are always warmer than mean annual air temperatures, varying from 1 degree F at Keg River, Alta to 12 degrees F at Taurcanis, N.W.T. Complications arise for good comparisons because the mean annual ground temperatures decrease with depth to about 50-100 ft and then steadily increase and further, some individual ground temperature values above the level of zero temperature amplitude may be higher or lower than the annual mean depending on depth and time of year. It appears that an accurate prediction of mean annual ground temperature and the occurence of permafrost at a site solely from the mean annual air temperature is subject to variations by other climate and terrain factors. Many more observations are required before anything more than a broad relation can be established. La formation de pergélisol dépend essentiellement du climat et celui-ci est en même temps l'un des facteurs les plus importants pour son maintien. La température dans la zone mé ridionale de la région pergélisolée varie en général entre les isothermes de 25 et de 30 degrés F pour ce qui est de la température annuelle moyenne de l'air d'un océan à l'autre. Les variations locales dépendent du microclimat et des conditions du terrain. Dans le pergélisol, les températures diminuent progressivement de la surface du sol à une profondeur d'environ 50 à 100 pieds; mais sous cette profondeur, la température augmente progressivement sous l' effet de la chaleur provenant de ...