| 1. |
- Dammann, Dyre Oliver, 1985, et al.
(author)
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Assessing sea ice trafficability in a changing arctic
- 2018
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In: Arctic. - : The Arctic Institute of North America. - 1923-1245 .- 0004-0843. ; 71:1, s. 59-75
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Journal article (peer-reviewed)abstract
- Arctic sea ice has undergone rapid changes during the last few decades, with negative implications for over-ice travel and on-ice operations, which benefit from services provided by the sea ice. A Parameter-based Trafficability Hierarchy (PATH) is presented here as a framework for developing quantitative assessment strategies that can guide planning and execution of operations on or near sea ice and quantify the impacts of recent changes on ice use. A PATH assessment has been completed for three case studies in Arctic Alaska. These cases, which correspond to a range of different icescapes and ice uses, identify and quantify different parameters linked to trafficability and safe operations. For ice road applications, PATH was used to determine an ice thickness compensation factor, a factor increasing the minimal thickness threshold for operations, to help translate sporadic auger ice thickness measurements along the Kotzebue-Kiana community ice road into an envelope for safe operations. A compensation factor as high as 1.5 was found to be necessary to ensure safety because of the high local thickness variability that is currently a concern for ice road operators. A PATH assessment of ice roughness for ice trail routing at Utqiaġvik draws on satellite remote sensing and is relevant for over-ice travel in general, including escape, evacuation, and rescue. We compared the routing of local snowmobile trails with Synthetic Aperture Radar (SAR) data products to identify specific ranges of ice conditions, roughness, and topography favored for ice trail construction. The same combination of data sources was used to identify potentially beneficial trail routes. Finally, an ice stability and safety assessment was completed for ice road construction and maintenance by industry near the Northstar Island oil production facility. We evaluated small-scale ice displacement data obtained from SAR interferometry to infer internal ice strain and stress and used these data in assessing the potential for fractures to reduce load-bearing capacity.
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| 2. |
- Jakobsson, Martin, et al.
(author)
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Arctic Ocean Bathymetry : A Necessary Geospatial Framework
- 2015
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In: Arctic. - : The Arctic Institute of North America. - 0004-0843 .- 1923-1245. ; 68, s. 41-47
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Journal article (peer-reviewed)abstract
- Most ocean science relies on a geospatial infrastructure that is built from bathymetry data collected from ships underway, archived, and converted into maps and digital grids. Bathymetry, the depth of the seafloor, besides having vital importance to geology and navigation, is a fundamental element in studies of deep water circulation, tides, tsunami forecasting, upwelling, fishing resources, wave action, sediment transport, environmental change, and slope stability, as well as in site selection for platforms, cables, and pipelines, waste disposal, and mineral extraction. Recent developments in multibeam sonar mapping have-so dramatically increased the resolution with which the seafloor can be portrayed that previous representations must be considered obsolete. Scientific conclusions based on sparse bathymetric information should be re-examined and refined. At this time only about 11% of the Arctic Ocean has been mapped with multibeam; the rest of its seafloor area is portrayed through mathematical interpolation using a very sparse depth-sounding database. In order for all Arctic marine activities to benefit fully from the improvement that multibeam provides, the entire Arctic Ocean must be multibeam-mapped, a task that can be accomplished only through international coordination and collaboration that includes the scientific community, naval institutions, and industry.
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| 3. |
- Kullman, Leif, et al.
(author)
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New Aspects of High-Mountain Palaeobiogeography : A Synthesis of Data from Forefields of Receding Glaciers and Ice Patches in the Tarna and Kebnekaise Mountains, Swedish Lapland
- 2015
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In: Arctic. - : The Arctic Institute of North America. - 0004-0843 .- 1923-1245. ; 68:2, s. 141-152
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Journal article (peer-reviewed)abstract
- Recent recession of high-mountain glacier ice and perennial snow and ice patches has exposed megafossil and macrofossil tree remnants and peat, offering a new source of Holocene high alpine vegetation history in the Scandes. Radiocarbon dates of 90 tree megafossils from Swedish Lapland, 29 of which had not previously been published, range from 11 980 to 1950 cal yr BP. During the interval 9500-8500 cal yr BP, mountain birch (Betula pubescens ssp. czerepanovii) and Scots pine (Pinus sylvestris) grew 600-700 m higher upslope than they do today, which is a new and remarkable discovery. Subsequently, tree density gradually declined at higher elevations, and as the tree line moved downslope, the ratio of Betula to Pinus increased. Tree growth ceased around 4500 cal yr BP, presumably in response to the return of perennial ice and snow. A short episode of resumed tree growth of Betula indicates conditions warmer than present around 2000 years ago. Between c. 8500 and 7300 cal yr BP, Picea abies, Larix sibirica, Populus tremula, Sorbus aucuparia and Alnus incana were subordinate species on a forest floor dominated by plant species characteristic of prealpine or subalpine woodlands. Growth of trees as much as 700 m higher upslope than today around 9500 cal yr BP implies that summer temperatures at that time may have been 3.0 degrees C warmer than today's temperatures (corrected for land uplift). This inferred temperature difference between the early Holocene and the present concurs with changes in the Earth's orbital parameters.
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| 4. |
- Kullman, Leif, et al.
(author)
-
New Aspects of High-Mountain Palaeobiogeography : A Synthesis of Data from Forefields of Receding Glaciers and Ice Patches in the Tarna and Kebnekaise Mountains, Swedish Lapland
- 2015
-
In: Arctic. - 0004-0843 .- 1923-1245. ; 68:2, s. 141-152
-
Journal article (peer-reviewed)abstract
- Recent recession of high-mountain glacier ice and perennial snow and ice patches has exposed megafossil and macrofossil tree remnants and peat, offering a new source of Holocene high alpine vegetation history in the Scandes. Radiocarbon dates of 90 tree megafossils from Swedish Lapland, 29 of which had not previously been published, range from 11 980 to 1950 cal yr BP. During the interval 9500-8500 cal yr BP, mountain birch (Betula pubescens ssp. czerepanovii) and Scots pine (Pinus sylvestris) grew 600-700 m higher upslope than they do today, which is a new and remarkable discovery. Subsequently, tree density gradually declined at higher elevations, and as the tree line moved downslope, the ratio of Betula to Pinus increased. Tree growth ceased around 4500 cal yr BP, presumably in response to the return of perennial ice and snow. A short episode of resumed tree growth of Betula indicates conditions warmer than present around 2000 years ago. Between c. 8500 and 7300 cal yr BP, Picea abies, Larix sibirica, Populus tremula, Sorbus aucuparia and Alnus incana were subordinate species on a forest floor dominated by plant species characteristic of prealpine or subalpine woodlands. Growth of trees as much as 700 m higher upslope than today around 9500 cal yr BP implies that summer temperatures at that time may have been 3.0 degrees C warmer than today's temperatures (corrected for land uplift). This inferred temperature difference between the early Holocene and the present concurs with changes in the Earth's orbital parameters.
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| 5. |
- Lomac-MacNair, Kate, et al.
(author)
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Seal Occurrence and Habitat Use during Summer in Petermann Fjord, Northwestern Greenland
- 2018
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In: Arctic. - : The Arctic Institute of North America. - 0004-0843 .- 1923-1245. ; 71:3, s. 334-348
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Journal article (peer-reviewed)abstract
- Ice-associated seals are considered especially susceptible and are potentially the first to modify distribution and habitat use in response to physical changes associated with the changing climate. Petermann Glacier, part of a unique ice-tongue fjord environment in a rarely studied region of northwestern Greenland, lost substantial sections of its ice tongue during major 2010 and 2012 calving events. As a result, changes in seal habitat may have occurred. Seal occurrence and distribution data were collected in Petermann Fjord and adjacent Nares Strait region over 27 days (2 to 28 August) during the multidisciplinary scientific Petermann 2015 Expedition on the icebreaker Oden. During 239.4 hours of dedicated observation effort, a total of 312 individuals were recorded, representing four species: bearded seal (Erignathus barbatus), hooded seal (Crystophora cristata), harp seal (Pagophilus groenlandicus), and ringed seal (Pusa hispida). Ringed seals were recorded significantly more than the other species (chi(2) = 347.4, df = 3, p < 0.001, n = 307). We found significant differences between species in haul-out (resting on ice) behavior (chi(2) = 133.1, df = 3, p < 0.001, n = 307). Bearded seals were more frequently hauled out (73.1% n = 49), whereas ringed seals were almost exclusively in water (93.9%, n = 200). Differences in average depth and ice coverage where species occurred were also significant: harp seals and bearded seals were found in deeper water and areas of greater ice coverage (harp seals: 663 +/- 366 m and 65 +/- 14% ice cover; bearded seals: 598 +/- 259 m and 50 +/- 21% ice cover), while hooded seals and ringed seals were found in shallower water with lower ice coverage (hooded seals: 490 +/- 163 m and 38 +/- 19% ice cover; ringed seals: 496 +/- 235 m, and 21 +/- 20% ice cover). Our study provides an initial look at how High Arctic seals use the rapidly changing Petermann Fjord and how physical variables influence their distribution in one of the few remaining ice-tongue fjord environments.
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