Physical and temporal factors controlling the development of near-surface ground ice at Illisarvik, western Arctic coast, Canada

2012 ◽  
Vol 49 (9) ◽  
pp. 1096-1110 ◽  
Author(s):  
H. Brendan O’Neill ◽  
C.R. Burn
Keyword(s):  
Important Variable ◽  
Lake Basin ◽  
Ground Ice ◽  
Near Surface ◽  
Marginal Areas ◽  
Permafrost Table ◽  
Western Arctic ◽  
Arctic Coast ◽  
Ice Content ◽  
Secondary Variable

Near-surface permafrost was sampled in summer 2010 at 26 sites in the Illisarvik drained-lake basin and nine sites in the surrounding tundra on Richards Island, NWT, to investigate the growth of segregated near-surface ground ice. Permafrost and ground ice have developed in the lake basin since drainage in 1978. The lake bed soils are predominantly silts of varying moisture and organic-matter contents, with sandier soils near the lake margins. Excess-ice contents in the basin were also variable, and ice enrichment was observed to a maximum depth of 60 cm below the 2010 permafrost table. Shrub-covered, wet areas had the highest mean excess-ice content in the top 50 cm of permafrost (10%), while grassy, dryer areas (4%) and poorly vegetated marginal areas (<1%) were less enriched with ice. Site wetness was the most important variable associated with near-surface excess-ice content in the lake basin. Silt content was a secondary variable. Mean excess-ice content in the top 50 cm of permafrost at tundra sites (25%) was much greater than in the basin, with ice enrichment to greater depths, likely a result of the time available for permafrost aggradation since the early Holocene climatic optimum.

The Origin of Massive Icy Beds in Permafrost, Western Arctic Coast, Canada

1971 ◽  
Vol 8 (4) ◽  
pp. 397-422 ◽  
Author(s):  
J. Ross Mackay
Keyword(s):  
The Arctic ◽  
Ground Ice ◽  
Widespread Occurrence ◽  
Sea Floor ◽  
Western Arctic ◽  
Arctic Coast ◽  
Ice Content ◽  
Glacier Advance ◽  
Drill Holes ◽  
Level Lowering

Massive beds of ground ice are shown to exist along the arctic coastal plain east of the Alaska–Yukon boundary for a distance of at least 500 km. The massive ground ice can be seen in both undisturbed and glacially disturbed Pleistocene sediments. An examination of several thousand seismic shot hole logs, from drill holes of 15 to 35 m in depth, also corroborates the widespread occurrence of ground ice. The icy beds typically have an ice content, defined in terms of the weight of ice to dry soil, in excess of 200% for sections as much as 35 m thick. A theory is presented which suggests that: the ice is of segregation origin; the source of excess water was from the expulsion of ground water during the freezing of sands; and high pore water pressures, favorable to ice segregation, developed beneath an aggrading impermeable permafrost cover. Permafrost aggradation may have occurred either on an exposed sea floor during a period of sea level lowering which would have accompanied a glacier advance, or following a warm interval in which there had been deep thaw. Similarities in the origin of pingo ice and massive ice are discussed.

scholarly journals New ground ice maps for Canada using a paleogeographic modelling approach

2019 ◽  
Vol 13 (3) ◽  
pp. 753-773 ◽  
Author(s):  
H. Brendan O'Neill ◽  
Stephen A. Wolfe ◽  
Caroline Duchesne
Keyword(s):  
Glacial Lake ◽  
Significant Advance ◽  
Small Scale ◽  
Permafrost Degradation ◽  
Field Observations ◽  
Tree Line ◽  
Ground Ice ◽  
Near Surface ◽  
Western Arctic ◽  
Modelling Approach

Abstract. Ground ice melt caused by climate-induced permafrost degradation may trigger significant ecological change, damage infrastructure, and alter biogeochemical cycles. The fundamental ground ice mapping for Canada is now >20 years old and does not include significant new insights gained from recent field- and remote-sensing-based studies. New modelling incorporating paleogeography is presented in this paper to depict the distribution of three ground ice types (relict ice, segregated ice, and wedge ice) in northern Canada. The modelling uses an expert-system approach in a geographic information system (GIS), founded in conceptual principles gained from empirically based research, to predict ground ice abundance in near-surface permafrost. Datasets of surficial geology, deglaciation, paleovegetation, glacial lake and marine limits, and modern permafrost distribution allow representations in the models of paleoclimatic shifts, tree line migration, marine and glacial lake inundation, and terrestrial emergence, and their effect on ground ice abundance. The model outputs are generally consistent with field observations, indicating abundant relict ice in the western Arctic, where it has remained preserved since deglaciation in thick glacigenic sediments in continuous permafrost. Segregated ice is widely distributed in fine-grained deposits, occurring in the highest abundance in glacial lake and marine sediments. The modelled abundance of wedge ice largely reflects the exposure time of terrain to low air temperatures in tundra environments following deglaciation or marine/glacial lake inundation and is thus highest in the western Arctic. Holocene environmental changes result in reduced ice abundance where the tree line advanced during warmer periods. Published observations of thaw slumps and massive ice exposures, segregated ice and associated landforms, and ice wedges allow a favourable preliminary assessment of the models, and the results are generally comparable with the previous ground ice mapping for Canada. However, the model outputs are more spatially explicit and better reflect observed ground ice conditions in many regions. Synthetic modelling products that incorporated the previous ground ice information may therefore include inaccuracies. The presented modelling approach is a significant advance in permafrost mapping, but additional field observations and volumetric ice estimates from more areas in Canada are required to improve calibration and validation of small-scale ground ice modelling. The ground ice maps from this paper are available in the supplement in GeoTIFF format.

Surficial materials and related ground ice conditions, Slave Province, N.W.T., Canada

1999 ◽  
Vol 36 (7) ◽  
pp. 1227-1238 ◽  
Author(s):  
Lynda A Dredge ◽  
Daniel E Kerr ◽  
Stephen A Wolfe
Keyword(s):  
Gulf Coast ◽  
Regional Scale ◽  
Coarse Grained ◽  
Silty Clay ◽  
Ground Ice ◽  
Wide Range ◽  
Ice Conditions ◽  
Western Arctic ◽  
Climatic History ◽  
Ice Content

Surficial mapping and geologic information on the nature and evolution of surficial materials in the Slave geologic province indicate that the geotechnical properties and potential ground ice contents associated with these materials depend largely upon their provenance, depositional conditions, and the postglacial climatic history. This information may be used to provide a regional-scale view of the distribution of ground ice conditions and terrain sensitivities associated with various surficial materials. In till veneers and blankets, ground ice content is generally low, as suggested by lack of thermokarst and other permafrost features. However, distinctive surface relief in hummocky till including kettle depressions, rim-ridges, and shallow thaw flowslides may be attributed to massive ice, resulting in sensitive till terrain. Although many outwash sediments have low ice contents near the surface, massive ice ranging from 5 to 10 m thick is present in some eskers and ice-contact outwash sediments. These are associated with thermokarst, slope movement, and collapse features, indicative of meltout or creep of large bodies of massive ice. The terrain sensitivity associated with these deposits is typically low to moderate, due to the coarse-grained nature of the sediments. In contrast, terrain sensitivity is high, and active-layer detachment slides are common along the Coronation Gulf coast where frozen silty clay marine sediments contain a wide range of ice contents. Results from this study may be applied to a much more extensive area of the glaciated western Arctic mainland and adjacent Arctic coastal plain in which materials with a similar glacial history are found.

scholarly journals New ground ice maps for Canada using a paleogeographic modelling approach

2018 ◽  
Author(s):  
H. Brendan O'Neill ◽  
Stephen A. Wolfe ◽  
Caroline Duchesne
Keyword(s):  
Glacial Lake ◽  
Significant Advance ◽  
Small Scale ◽  
Permafrost Degradation ◽  
Field Observations ◽  
Tree Line ◽  
Ground Ice ◽  
Near Surface ◽  
Western Arctic ◽  
Modelling Approach

Abstract. Ground ice melt caused by climate-induced permafrost degradation may trigger significant ecological change, damage infrastructure, and alter biogeochemical cycles. The fundamental ground ice mapping for Canada is now > 20 years old, and does not include significant new insights gained from recent field and remote sensing based studies. New modelling incorporating paleogeography is presented in this paper to depict the distribution of three ground ice types (massive ice and icy sediments, segregated ice, and wedge ice) in northern Canada. The modelling uses an expert-system approach in a geographic information system (GIS), founded in conceptual principles gained from empirically-based research, to predict ground ice abundance in near-surface permafrost. Datasets of surficial geology, deglaciation, paleovegetation, glacial lake and marine limits, and modern permafrost distribution allow representations in the models of paleoclimatic shifts, tree line migration, marine and glacial lake inundation, and terrestrial emergence, and their effect on ground ice abundance. The model outputs are generally consistent with field observations, indicating abundant relict massive ice and icy sediments in the western Arctic, where it has remained preserved since deglaciation in thick glacigenic sediments in continuous permafrost. Segregated ice is widely distributed in fine-grained deposits, occurring in highest abundance in glacial lake and marine sediments. The modelled abundance of wedge ice largely reflects the exposure time of terrain to low air temperatures in tundra environments following deglaciation or marine/glacial lake inundation, and is thus highest in the western Arctic. Holocene environmental changes result in reduced ice abundance where tree line advanced during warmer periods. Published observations of thaw slumps and ice exposures, segregated ice and associated landforms, and ice wedges allow a favourable preliminary assessment of the models, and the results are generally comparable with the previous ground ice mapping for Canada. However, the model outputs are more spatially explicit and better reflect observed ground ice conditions in some regions. Synthetic modelling products that incorporated the previous ground ice information may therefore include inaccuracies. The presented modelling approach is a significant advance in permafrost mapping, but additional field observations and volumetric ice estimates from more areas in Canada are required to improve calibration and validation of small-scale ground ice modelling.

Vertical distribution of excess ice in icy sediments and its statistical estimation from geotechnical data (Tuktoyaktuk Coastlands, Northwest Territories)

2021 ◽  
Author(s):  
Ariane Castagner ◽  
Stephan Gruber ◽  
Alexander Brenning
Keyword(s):  
Northwest Territories ◽  
Statistical Estimation ◽  
Canadian Arctic ◽  
Important Variable ◽  
Geotechnical Data ◽  
Surficial Geology ◽  
Geomorphic Response ◽  
Arctic Coast ◽  
Ice Content ◽  
Planning And Construction

&lt;div&gt;Excess ice can be found in the form of massive ice and within icy sediments and is an important variable to quantify as it strongly influences the geomorphic response of landscapes to permafrost thaw. The melting of excess ice in the Western Canadian Arctic has led to thaw subsidence and an increase in the number and size of thaw slumps observed across the Northwest Territories which cause issues to Northern infrastructure and affect fluvial and lacustrine watersheds. The Inuvik-Tuktoyaktuk Highway (ITH) is the first all-weather road to reach the Canadian Arctic Coast and its planning and construction has resulted in a significant cryostratigraphic dataset of 566 boreholes, which forms the basis of this contribution. Although visible ice is often recorded in boreholes, it is not a reliable measure of excess ice content on its own and there is currently no reliable method to estimate the excess ice content of boreholes based on commonly available geotechnical data. In this study, a 16-borehole subset of the ITH dataset for which samples were processed for volumetric excess ice content is used to train a beta regression model that predicts the excess ice content of stratigraphic intervals in the study area based on interval depth, visible ice content, surficial geology, and material types. The resulting predictions are compared to recorded massive ice intervals in the same boreholes and show that excess ice within icy sediments can significantly contribute to potential thaw strain and should be considered alongside massive ice when making thaw strain estimates.&lt;/div&gt;

scholarly journals Semi-Automatic Fractional Snow Cover Monitoring from Near-Surface Remote Sensing in Grassland

2021 ◽  
Vol 13 (11) ◽  
pp. 2045
Author(s):  
Anaí Caparó Bellido ◽  
Bradley C. Rundquist
Keyword(s):  
Snow Cover ◽  
Near Infrared ◽  
Accuracy Assessment ◽  
Important Variable ◽  
Field Station ◽  
Near Surface ◽  
Fractional Snow Cover ◽  
Rgb Images ◽  
Phenological Metrics

Snow cover is an important variable in both climatological and hydrological studies because of its relationship to environmental energy and mass flux. However, variability in snow cover can confound satellite-based efforts to monitor vegetation phenology. This research explores the utility of the PhenoCam Network cameras to estimate Fractional Snow Cover (FSC) in grassland. The goal is to operationalize FSC estimates from PhenoCams to inform and improve the satellite-based determination of phenological metrics. The study site is the Oakville Prairie Biological Field Station, located near Grand Forks, North Dakota. We developed a semi-automated process to estimate FSC from PhenoCam images through Python coding. Compared with previous research employing RGB images only, our use of the monochrome RGB + NIR (near-infrared) reduced pixel misclassification and increased accuracy. The results had an average RMSE of less than 8% FSC compared to visual estimates. Our pixel-based accuracy assessment showed that the overall accuracy of the images selected for validation was 92%. This is a promising outcome, although not every PhenoCam Network system has NIR capability.

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