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This study is the second attempt to use the Basal Temperature of Snow (BTS) method to map permafrost in mountainous regions of northwestern Canada. It differs from the first study which took place in Wolf Creek in terms of (1) the methodology used to evaluate BTS, (2) the strategy used to avoid spatial autocorrelation in residuals, and (3) the climatic regions investigated. Two study areas, part of the Ruby Range (61° 12' N, 138° 19' W) and Haines Summit (59° 37' N, 136° 27' W) were selected for BTS sampling based on differing climatic conditions and previous knowledge of permafrost elevations from active rock glaciers. A total of 30 BTS measurements were made in the Ruby Range in the winter of 2006 and a total...
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Lake sediment cores collected from four lakes (Upper Fly Lake 61.04°N, 138.09°W, 1326 m a.s.l.; Jenny Lake 61.04°N, 138.36°W, 817 m. a.s.l.; Donjek Kettle 61.69°N, 139.76°W, 732 m a.s.l.; Lake WP02 61.48°N, 139.97°W, 1463 m a.s.l.) in the southwest Yukon provide records of postglacial climatic variability in the region. A 13,000 year pollen record from Upper Fly Lake indicated that herbaceous tundra existed on the landscape from 13.6 to 11 ka, followed by birch shrub tundra until 10 ka, when Picea forests were established in the region. Pollen-, chironomid-, and ostracode-inferred paleoclimate reconstructions showed a long-term cooling with increasing moisture from the late glacial through the Holocene. The early...
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Permanent electrode arrays were set up at ten monitoring sites from Whitehorse, Yukon, to Fort St. John, British Columbia, in order to gain a clearer perspective of the effectiveness of electrical resistivity tomography (ERT) monitoring over an annual cycle of freezing and thawing. This research forms part of a longer-term project that is attempting to use ERT to examine changes in permafrost resulting from climate change. Inter-site and intra-site variability were examined by installing and maintaining data-loggers to monitor active layer and shallow permafrost temperatures, air temperatures, and snow depths at each site from August 2010-August 2011. Additional site information was collected on each ERT survey...
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Near-surface air temperature inversions are a common element of northern environments. Seasonal and inter-annual variations of low-level inversion characteristics were examined using 47 years of twice-daily radiosonde data from Whitehorse airport (1956-2003). Nocturnal low-level inversion events occurred throughout the year in 68% of the 0400h PST radiosonde ascents. Afternoon (1600h PST) inversion events, in contrast, were primarily a winter phenomena, limited to 24% of the readings between October and March, and were deepest and strongest during the winter months. Shorter, weaker, lower magnitude inversions appeared progressively more frequently during the 1974-2003 warming at Whitehorse. The impact (1956-2003)...
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Dendrochronological techniques were used to study white spruce ( Picea glauca [Moech] Voss) dynamics in the altitudinal forest-tundra ecotone in the southwest Yukon Territory. At two sampling sites, all Picea glauca individuals within 9 delineated quadrats in the forest-tundra and forest were sampled to estimate dates of establishment and growth variations using tree-ring chronologies. Regeneration in the forest-tundra ecotone was low from the late 1800s to the mid-1900s, however has increased since the 1920s. Recent peak periods of establishment parallel increased radial growth trends, which may have resulted from the long-term warming trend of the 20 th century. Seedling proximity to pre-established individuals...
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Solifluction lobe process and morphology were studied on an alpine slope (1800 m a.s.l) above Kluane Lake, south-western Yukon Territory. Contemporary rates of surface movements, measured by theodolite survey, were found to be greatest in the first two weeks of spring thaw, and movements were consistently faster on lobe treads than on lobe risers. Precise monitoring of thaw-consolidation parameters on a lobe indicated that most thaw-settlement occurred when the soil was saturated to the surface. At the slope scale, surface rates increased downslope in response to gradients in soil moisture, while long-term rates of lobe advance, inferred from 14 C dating of buried organic horizons, were found to be similar among...
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The data from nine permafrost thermal monitoring sites at widely separated locations across northern Canada were examined individually, spatially, and temporally. Three sites are in Nunavut (Alert, Iqaluit, and Baker Lake), two in the Northwest Territories (Table Mountain and Wrigley), and four in the Yukon Territory (Wolf Creek, Sixty Mile, Alpine Burwash, and Red Creek). The sites have between one and five boreholes that are instrumented to between 3 and 60 m with records of varying durations. Most of the boreholes are co-located with weather stations recording air temperatures and snow depths. A comprehensive analysis of each site is presented assessing the relations between climate and permafrost temperatures,...
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This study investigates the succession following fire in a relatively dry area of the boreal forest, the Shakwak Trench, southwest Yukon. The postfire successional regime is determined by an analysis of age structure and composition of tree populations in stands of different ages. The dendroecological approach used in this study is based on the sampling of one plot in each of 11 fires ranging from A.D. 1844-1998. Picea glauca established 0-4 years after fire and reached a period of maximum establishment after 20-40 years. Populus tremuloides was generally recruited immediately after fire and was no longer present after approximately 20 years, at which point, the Picea glauca began to dominate. Salix spp. were found...
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In Canada's western Arctic, perennial discharge from permafrost watersheds is the surface manifestation of active groundwater flow systems, yet understanding the mechanisms of groundwater recharge and flow in periglacial environments remains enigmatic. This thesis addresses questions on how and where groundwater recharge occurs. Watersheds were selected in Yukon (Fishing Branch River at Bear Cave Mountain) and the Northwest Territories at latitudes spanning from continuous to discontinuous permafrost (five tributary rivers to the Mackenzie River from Wrigley to Aklavik). All are characterized by perennial flow with open water in the winter, and discharge from sedimentary formations of karstic carbonates and evaporate...
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Numerous forest fires occurred during the summer of 2004 in the Klondike Goldfields region of the Yukon Territory, an area of extensive discontinuous permafrost. More than 35 shallow detachment failure landslides developed in subsequent weeks in Steele Creek, a small drainage basin located about 60 km south of Dawson City. Preliminary observations of the failures and near-surface thermal regime were made through freeze-up of 2004 and continued in the summers of 2005 and 2006. Detachment failures were mapped and individual sites were surveyed. Air and ground temperatures were measured in burned and unburned areas. In addition, two-dimensional DC resistivity transects were used to examine subsurface conditions in...
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Speleothems are rare in high-latitude and high-altitude caves, which is why Bear Cave in the north-western Yukon Territory is particularly unique, as it houses some of the oldest and highest latitude speleothem in the world. In this study, a detailed petrographic and geochemical study was conducted along the profile of a 68-cm long late-Miocene flowstone from Bear Cave (BC1) to reveal the processes that took place at the time of deposition, in addition to those that followed, in aims to determine its paleoclimatic suitability. These studies suggest that softer facies are generally representative of disequilibrium conditions, where in-filled textures provide evidence for diagenic phenomena; these processes ultimately...
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This study investigates the runoff process and groundwater behavior in a subarctic watershed called Wolf Creek Research Basin, in Whitehorse, Yukon Territory, Canada. This basin is underlain by discontinuous permafrost that is typical of high latitude watersheds. Goundwater supports the stream flow year round and dominated the hydrology in most of the study period as baseflow. The baseflow was concentrated in dissolved ions. However, the baseflow was diluted during the melt season in May and June of 2012. Multiple chemical and isotopic tracers were used to develop a robust three-component (groundwater, soilwater and precipitation) mixing model for runoff generation. The concentrations of weathering ions decreased...
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The impact of recent climate change on permafrost distribution was evaluated by repeating the 1964 survey of Roger Brown along the Alaska Highway from Whitehorse, YT to Fort St. John, BC in August 2007 and 2008. Results demonstrate that: (1) significant degradation of permafrost has occurred over the past four decades, especially in the southernmost part of the route where 67% of the permafrost sites in 1964 no longer exhibit perennially frozen conditions; (2) the mapped southern limit of discontinuous permafrost appears to have shifted roughly 75 km northward; (3) most of the permafrost still present in the study area is in peat or under thick organic mats, which probably relates to a large thermal offset or to...
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This study is the first known attempt in North America to use the basal temperature of snow (BTS) method to predict the distribution of mountain permafrost. The study site, Wolf Creek Research Basin, Yukon Territory (60°30'N, 135°13'W), is a 195 km 2 basin ranging in elevation from 650-2100 m with a mean annual air temperature of about -4°C at 1235 m a.s.l. A modeled BTS surface, based on 394 measured BTS values and with elevation and potential incoming solar radiation as independent variables, was created within a GIS environment with an r2 value similar to European results. The distribution of permafrost within the basin was identified from pits and boreholes. A subsequent logistic regression was used to compare...
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The links between climate and permafrost are well known, but the precise nature of the relationship between air and ground temperatures remains poorly understood, particularly in complex mountain environments. Although previous studies indicate that elevation and potential incoming solar radiation (PISR) are the two leading factors contributing to the existence of permafrost at a given location, additional factors may also contribute significantly to the existence of mountain permafrost, including vegetation cover, snow accumulation and the degree to which individual mountain landscapes are prone to air temperature inversions. Current mountain permafrost models consider only elevation and aspect, and have not been...
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This biogeographical study documents the modern distribution of ostracodes in the southwest Yukon Territory and northern British Columbia, Canada. The study tested the hypothesis that dissolved ion composition and concentrations of the lake water are the primary determinants of the distribution of modern ostracodes in this region. A total of 28 freshwater species representing 8 genera were identified in the 33 study lakes. Species common in the southwest Yukon are widely distributed throughout North America, and include Cyclocypris ampla , Candona candida , Cypria turneri , Cypria ophtalmica , and Candona protzi . Concentrations of ostracode valves were highest in four lakes with moderate conductivity values ranging...
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Basal Temperature of Snow (BTS) measurements were used as the primary inputs to a high resolution (30 x 30 m grid cells) empirical-statistical regional permafrost probability model for the southern and central Yukon, and northernmost British Columbia (59° - 65°N). Data from seven individual study areas distributed across the region were combined using a blended distance decay technique, with an eighth area used for validation. The model predictions are reasonably consistent with previous permafrost maps for the area with some notable differences and a much higher level of detail. The modelling gives an overall permafrost probability of 52%. North of 62°N, permafrost becomes more extensive in the lowland areas whereas...
    map background search result map search result map Spatial and temporal variability in permafrost conditions, northern Canada Evaluation of the basal temperature of snow (BTS) method to map permafrost in complex mountainous terrain, Wolf Creek, Yukon Territory Dendroecological analysis of successional dynamics after fire in the Shakwak Trench, southwest Yukon Territory High-resolution Permafrost Distribution Modelling for the Central and Southern Yukon, and Northwestern British Columbia, Canada Seasonal cycling in electrical resistivities at ten thin permafrost sites, southern Yukon and northern British Columbia Development of solifluction lobes, Kluane Range, Yukon Territory Modern distribution of freshwater ostracodes in the southwest Yukon Territory and northern British Columbia, Canada Validation of the Basal Temperature of Snow (BTS) method to map permafrost in complex mountainous terrain, Ruby Range, Yukon Territory and Haines Summit, British Columbia Holocene environmental variability inferred from lake sediments, southwest Yukon Territory, Canada The Geochemistry and Runoff Process in Wolf Creek Research Basin, Whitehorse, Yukon Territory Geochemistry and noble gases of permafrost groundwater and ground ice in Yukon and the Northwest Territories, Canada Characteristics of low-level temperature inversions, Whitehorse Yukon Territory: 1956--2003 Air and Ground Surface Temperature Relations in a Mountainous Basin, Wolf Creek, Yukon Territory Historic Change in Permafrost Distribution in Northern British Columbia and Southern Yukon Territory, Canada Preservation and diagenesis in ancient speleothems: evidence from Bear Cave, Yukon Territory The impact of forest fire on permafrost slopes Klondike area, Yukon Territory White spruce dynamics in the forest-tundra ecotone, the southwest Yukon Territory The impact of forest fire on permafrost slopes Klondike area, Yukon Territory Air and Ground Surface Temperature Relations in a Mountainous Basin, Wolf Creek, Yukon Territory The Geochemistry and Runoff Process in Wolf Creek Research Basin, Whitehorse, Yukon Territory Characteristics of low-level temperature inversions, Whitehorse Yukon Territory: 1956--2003 Evaluation of the basal temperature of snow (BTS) method to map permafrost in complex mountainous terrain, Wolf Creek, Yukon Territory Dendroecological analysis of successional dynamics after fire in the Shakwak Trench, southwest Yukon Territory Development of solifluction lobes, Kluane Range, Yukon Territory Validation of the Basal Temperature of Snow (BTS) method to map permafrost in complex mountainous terrain, Ruby Range, Yukon Territory and Haines Summit, British Columbia Holocene environmental variability inferred from lake sediments, southwest Yukon Territory, Canada White spruce dynamics in the forest-tundra ecotone, the southwest Yukon Territory Preservation and diagenesis in ancient speleothems: evidence from Bear Cave, Yukon Territory Modern distribution of freshwater ostracodes in the southwest Yukon Territory and northern British Columbia, Canada High-resolution Permafrost Distribution Modelling for the Central and Southern Yukon, and Northwestern British Columbia, Canada Geochemistry and noble gases of permafrost groundwater and ground ice in Yukon and the Northwest Territories, Canada Seasonal cycling in electrical resistivities at ten thin permafrost sites, southern Yukon and northern British Columbia Historic Change in Permafrost Distribution in Northern British Columbia and Southern Yukon Territory, Canada Spatial and temporal variability in permafrost conditions, northern Canada