WITHIN-SLOPE VARIABILITY OF GROUND HEAT FLUX, SUBARCTIC YUKON

This study examined local variability of heat flux within a north-facing hillslope in Wolf Creek basin, Yukon, during the thawed season of 1997. Ground heat flux was calculated by: (1) assessing vertical conduction and convection inputs (QGv) using near-surface temperature gradients and rainfall and (2) combining the sensible heat from ground temperature change with the latent heat associated with melting ground ice (QGs). Seasonally, the coefficient of variation (cv) of QGv was 20%, with most of the variation accounted for by changes in wetness and soil properties. Vertical convection of heat by infiltrating rainfall accounted for less than 3% of QGv. Measurements of QGs, which incorporate lateral heat transfer associated with groundwater flow, has a cv of 40%. Footslope sites do not have permafrost because of downslope advection of heat from groundwater and QGs was 2 to 3 times greater than upslope permafrost sites. QGv and QGs were similar at the upslope locations, however, the active layer depth varies depending on the ice content of the frozen soil. [Key words: ground heat flux, permafrost, subarctic, energy balance.]