Permafrost Patch Size Near the Margins of Discontinuous Permafrost, Southern Yukon and Northern B.C.

Abstract

This research focused on measuring permafrost patch size and related variables between Fort St. John, BC and Whitehorse, YT. Methods used included electrical resistivity tomography, climate monitoring, active layer measurement, analysis of historical aerial photos, and on-site near-vertical aerial imaging. Where permafrost is present along the transect, mean annual air temperature (2010-2014) varied from -3.3 ºC to -0.9 ºC, mean annual ground surface temperature from 0.7 ºC to 2.4 ºC and mean annual ground temperature from -0.3 ºC to 0.2 ºC (at TTOP). Permafrost patches are in the order of 10 – 50 000 m2 in area and there is a strong positive log-log relationship between patch area and maximum permafrost thickness. A conceptual model of permafrost patch size evolution under a warming climate is proposed. It is concluded that permafrost patch size depends on site-specific characteristics, the time since permafrost began to degrade and the local climate conditions.