Observations of the "Thermal Offset" in Near-Surface Mean Annual Ground Temperatures at Several Sites near Mayo, Yukon Territory, Canada

Abstract

Temperature profiles in the surface layers of the ground were measured frequently over a 12-month period beginning in May 1984 at seven sites near Mayo, Yukon Territory. Permafrost is present at six of the sites. The mean annual ground temperature profile at each site displays a thermal offset, with measured mean annual temperatures in the active layer up to 1.7 degrees C higher than in permafrost. Similar mean annual soil temperature profiles are presented from other stations in northern Canada and the U.S.S.R. Such near-surface inflections are not included in conventional models of the thermal regime of permafrost. The data indicate that equilibrium or aggrading permafrost may be present at sites where the mean annual ground surface temperature is above 0 degrees C.

Key words: permafrost, soil temperature