Near-surface permafrost conditions, Kendall Island Bird Sanctuary, western Arctic coast, Canada

Investigations were conducted in 2005-2009 at the outer Mackenzie Delta to characterize near-surface permafrost and active-layer (AL) conditions for a range of geomorphic and topographic settings in alluvial and upland tundra, in order to determine relations between factors controlling the distribution of near-surface ground ice and ground temperatures. Near-surface permafrost commonly has a high ground-ice content reflecting soil physical properties, moisture contents, and the processes and duration of ice formation. Ground temperatures and AL thickness are a function of surface temperatures.;Segregated and ice-wedge ice dominated near-surface ground-ice contents, but injection ice was also widespread. Segregated ground-ice distribution was positively associated with soil moisture availability, and mean excess ice content was higher in wetlands (34%) than in uplands (24%). Ice sheets were observed at the bases of hill slopes. Syngenetic ice wedges, developed in alluvial wetlands, constituted 1.5% of the ground-ice, were active, and maintained a subtle surface morphology. Many polygons contained one or more perennial frost blisters, and mound densities (up to >1700 km-2) increased downward along a slight topographic gradient.;Snow depth, governed by topography in uplands and vegetation in wetlands, was the primary influence on the ground thermal regime and permafrost distribution. The annual mean temperature at the top of permafrost (TTOP) was 2.4°C higher in the alluvial plain than in uplands because of greater snow depth and soil moisture. Similarly, freezeback duration was longer (on average 49 days) in the alluvial plain. Little interannual variation in AL thickness occurred during the study.;Data were gathered through field work and by interpretation of remotely sensed images. Direct measurements were made in the uppermost metre of permafrost to determine: the geomorphological controls on ice-lens accumulation; the ice wedges present in alluvial wetlands; and the origin of low mounds in the alluvial wetlands. Direct measurements were also made of the ground thermal regime over 3 years (2006 – 2009) to characterize temperature variation and the thermal influence of snow and AL conditions.