| 1. |
- Dammann, Dyre Oliver, 1985, et al.
(författare)
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Applications of radar interferometry for measuring ice motion
- 2021
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Ingår i: Proceedings of the International Conference on Port and Ocean Engineering under Arctic Conditions, POAC. - 0376-6756 .- 2077-7841. - 9781713841005 ; 2021-June
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Konferensbidrag (refereegranskat)abstract
- Ongoing sea ice decline has major implications for human activities near sea ice due to shorter seasons for on-ice operations and thinner ice with reduced load-bearing capacity and stability in many regions. This may in turn lead to increased sea ice mobility and impacts of ice movement on structures. We investigate space-borne radar interferometry (InSAR) as a technique to measure mm-scale sea ice motion of stationary ice over weeks to months. We find that InSAR enables mapping of bottomfast and stabilized landfast ice as regions with near-zero or reduced deformation. We further use this data to derive landfast ice strain and stress enabling estimation of the fracturing potential along the Northstar Island ice road in the Beaufort Sea, Alaska. We further examine ground-based radar interferometry (GRI) as a tool to collect continuous near real-time measurements on the km-scale not possible with InSAR. Based on GRI measurements conducted in Utqiaġvik, Alaska, we demonstrate the ability to evaluate ice strain in stationary ice and track vertical ice displacement due to tides. We also collected GRI measurements at 500 Hz during a drifting ice camp in the Beaufort Sea. The high sampling rate enabled tracking of continuous strain and detection of subtle variations in behavior between ice regimes. Through this work, interferometry shows promise as a tool to observe ice motion at the relevant scales needed for assessing sea ice stability, identify precursors to failure events, and better understand the relationship between different ice properties and loads on structures.
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| 2. |
- Dammann, Dyre Oliver, 1985, et al.
(författare)
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Assessing sea ice trafficability in a changing arctic
- 2018
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Ingår i: Arctic. - : The Arctic Institute of North America. - 1923-1245 .- 0004-0843. ; 71:1, s. 59-75
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Tidskriftsartikel (refereegranskat)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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| 3. |
- Dammann, Dyre Oliver, 1985, et al.
(författare)
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Evaluating landfast sea ice stress and fracture in support of operations on sea ice using SAR interferometry
- 2018
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Ingår i: Cold Regions Science and Technology. - : Elsevier BV. - 0165-232X. ; 149, s. 51-64
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Tidskriftsartikel (refereegranskat)abstract
- Recent Arctic warming has led to reduced sea-ice thickness and a more dynamic landfast ice cover with potential widespread consequences for ice users. Here, we develop an approach to assess the small-scale deformation of landfast ice critical to on-ice operations using synthetic aperture radar interferometry (InSAR). InSAR has previously proven successful in determining long-term qualitative climatology of ice deformation around on-ice operations, but is now used to explore its potential for providing quantitative guidance for ice road planning, construction, and maintenance. A validation effort using X-band SAR and high-precision GPS data over Elson Lagoon, Alaska, confirms the ability of InSAR to accurately estimate 3-dimensional sea ice strain values accumulated between SAR image acquisitions, using an inverse model. The inverse model was further applied to L-band InSAR data over the Northstar Island ice road near Prudhoe Bay, Alaska. Assuming an elasto-brittle rheology, the derived strain values yielded a spatial distribution of internal stress consistent with preexisting ice defects and morphology. In several localized regions of the study area, stress values exceeded expected yield stress. Resulting relative fracture intensity potential was shown to conform with local knowledge based on road inspections by engineers, and may be used to guide ice road planning, construction and maintenance efforts. The results presented here demonstrate that InSAR is an accurate tool for estimating landfast ice deformation and stability in support of ice use. The findings may also provide substantial new insights into the mechanics of landfast ice.
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| 4. |
- Dammann, Dyre Oliver, 1985, et al.
(författare)
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Instantaneous sea ice drift speed from TanDEM-X interferometry
- 2019
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Ingår i: Cryosphere. - : Copernicus GmbH. - 1994-0424 .- 1994-0416. ; 13:4, s. 1395-1408
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Tidskriftsartikel (refereegranskat)abstract
- The drift of sea ice is an important geophysical process with widespread implications for the ocean energy budget and ecosystems. Drifting sea ice can also threaten marine operations and present a hazard for ocean vessels and installations. Here, we evaluate single-pass along-track synthetic aperture radar (SAR) interferometry (S-ATI) as a tool to assess ice drift while discussing possible applications and inherent limitations. Initial validation shows that TanDEM-X phase-derived drift speed corresponds well with drift products from a ground-based radar at Utqiagvik, Alaska. Joint analysis of TanDEM-X and Sentinel-1 data covering the Fram Strait demonstrates that S-ATI can help quantify the opening/closing rate of leads with possible applications for navigation. S-ATI enables an instantaneous assessment of ice drift and dynamic processes that are otherwise difficult to observe. For instance, by evaluating sea ice drift through the Vilkitsky Strait, Russia, we identified short-lived transient convergence patterns. We conclude that S-ATI enables the identification and analysis of potentially important dynamic processes (e.g., drift, rafting, and ridging). However, current limitations of S-ATI are significant (e.g., data availability and they presently only provide the cross-track vector component of the ice drift field) but may be significantly reduced with future SAR systems.
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| 5. |
- Dammann, Dyre Oliver, 1985, et al.
(författare)
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Mapping Arctic Bottomfast Sea Ice Using SAR Interferometry
- 2018
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Ingår i: Remote Sensing. - : MDPI AG. - 2072-4292. ; 10:5
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Tidskriftsartikel (refereegranskat)abstract
- Bottomfast sea ice is an integral part of many near-coastal Arctic ecosystems with implications for subsea permafrost, coastal stability and morphology. Bottomfast sea ice is also of great relevance to over-ice travel by coastal communities, industrial ice roads, and marine habitats. There are currently large uncertainties around where and how much bottomfast ice is present in the Arctic due to the lack of effective approaches for detecting bottomfast sea ice on large spatial scales. Here, we suggest a robust method capable of detecting bottomfast sea ice using spaceborne synthetic aperture radar interferometry. This approach is used to discriminate between slowly deforming floating ice and completely stationary bottomfast ice based on the interferometric phase. We validate the approach over freshwater ice in the Mackenzie Delta, Canada, and over sea ice in the Colville Delta and Elson Lagoon, Alaska. For these areas, bottomfast ice, as interpreted from the interferometric phase, shows high correlation with local bathymetry and in-situ ice auger and ground penetrating radar measurements. The technique is further used to track the seasonal evolution of bottomfast ice in the Kasegaluk Lagoon, Alaska, by identifying freeze-up progression and areas of liquid water throughout winter.
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| 6. |
- Dammann, Dyre Oliver, 1985, et al.
(författare)
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Mapping pan-Arctic landfast sea ice stability using Sentinel-1 interferometry
- 2019
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Ingår i: Cryosphere. - : Copernicus GmbH. - 1994-0424 .- 1994-0416. ; 13:2, s. 557-577
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Tidskriftsartikel (refereegranskat)abstract
- Arctic landfast sea ice has undergone substantial changes in recent decades, affecting ice stability and including potential impacts on ice travel by coastal populations and on industry ice roads. We present a novel approach for evaluating landfast sea ice stability on a pan-Arctic scale using Synthetic Aperture Radar Interferometry (InSAR). Using Sentinel-1 images from spring 2017, we discriminate between bottomfast, stabilized, and nonstabilized landfast ice over the main marginal seas of the Arctic Ocean (Beaufort, Chukchi, East Siberian, Laptev, and Kara seas). This approach draws on the evaluation of relative changes in interferometric fringe patterns. This first comprehensive assessment of Arctic bottomfast sea ice extent has revealed that most of the bottomfast sea ice is situated around river mouths and coastal shallows. The Laptev and East Siberian seas dominate the aerial extent, covering roughly 4100 and 5100 km(2), respectively. These seas also contain the largest extent of stabilized and nonstabilized landfast ice, but are subject to the largest uncertainties surrounding the mapping scheme. Even so, we demonstrate the potential for using InSAR for assessing the stability of landfast ice in several key regions around the Arctic, providing a new understanding of how stability may vary between regions. InSAR-derived stability may serve for strategic planning and tactical decision support for different uses of coastal ice. In a case study of the Nares Strait, we demonstrate that interferograms may reveal early-warning signals for the breakup of stationary sea ice.
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| 7. |
- Dammann, Dyre Oliver, 1985, et al.
(författare)
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New possibilities using TSX and TDX in support of sea ice use
- 2018
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Ingår i: Proceedings of the European Conference on Synthetic Aperture Radar, EUSAR. - 2197-4403. ; 2018-June, s. 159-164
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Konferensbidrag (refereegranskat)abstract
- Sea ice travel and on-ice operations are important for Arctic coastal communities and industrial operations. Recent rapid changes in Arctic sea ice impacting ice users emphasize the need for assessment strategies capable of guiding decision makers and documenting change in key ice-use related parameters. In this paper, we demonstrate the potential for the use of TSX and TDX interferometry to assess deformation, drift, and roughness of coastal sea ice. Through on-ice validation using Structure-from-Motion and high-precision GPS, we demonstrate a high level of detail and accuracy potentially enabling the use of these products in decision making.
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| 8. |
- Dammann, Dyre Oliver, 1985, et al.
(författare)
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Traversing Sea Ice-Linking Surface Roughness and Ice Trafficability Through SAR Polarimetry and Interferometry
- 2018
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Ingår i: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing. - 2151-1535 .- 1939-1404. ; 11:2, s. 416-433
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Tidskriftsartikel (refereegranskat)abstract
- Arctic landfast sea ice is widely utilized for transportation by local communities and industry, with trafficability largely governed by ice roughness. Here, we introduce an approach to evaluate ice roughness that can aid in routing of ice roads and assessment of spatial variability and long-term changes in trafficability. Drawing on synthetic aperture radar (SAR) polarimetry, SAR interferometry (InSAR), and other remote sensing techniques, we integrated approaches into the trafficability assessment that had rarely been applied over sea ice in the past. Analysis of aerial photogrammetry obtained through structure-from-motion helped verify cm-scale accuracy of X-band InSAR-derived ridge height and link L-band polarimetric classification to specific roughness regimes. Jointly, these approaches enable a km-scale evaluation of ridge topography and cm-to m-scale roughness-both critical for the assessment of trafficability. A trafficability index was derived from such SAR data in conjunction with analysis of ice trail routing and ice use near Utqiaġvik, Alaska. The index identifies areas of reduced trafficability, associated with pressure ridges or rubble ice, and served to delineate favorable trail routes for different modes of transportation, with potential uses ranging from ice road routing to emergency evacuation. Community outreach is needed to explore how this approach could assist different ice users in reducing risk, minimizing trail or ice construction efforts, and improving safety.
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| 9. |
- Katlein, Christian, et al.
(författare)
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Platelet Ice Under Arctic Pack Ice in Winter
- 2020
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Ingår i: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 47:16
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Tidskriftsartikel (refereegranskat)abstract
- The formation of platelet ice is well known to occur under Antarctic sea ice, where subice platelet layers form from supercooled ice shelf water. In the Arctic, however, platelet ice formation has not been extensively observed, and its formation and morphology currently remain enigmatic. Here, we present the first comprehensive, long-term in situ observations of a decimeter thick subice platelet layer under free-drifting pack ice of the Central Arctic in winter. Observations carried out with a remotely operated underwater vehicle (ROV) during the midwinter leg of the MOSAiC drift expedition provide clear evidence of the growth of platelet ice layers from supercooled water present in the ocean mixed layer. This platelet formation takes place under all ice types present during the surveys. Oceanographic data from autonomous observing platforms lead us to the conclusion that platelet ice formation is a widespread but yet overlooked feature of Arctic winter sea ice growth.
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| 10. |
- Lee, Craig M., et al.
(författare)
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A Framework for the Development, Design and Implementation of a Sustained Arctic Ocean Observing System
- 2019
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Ingår i: Frontiers in Marine Science. - : Frontiers Media SA. - 2296-7745. ; 6
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Forskningsöversikt (refereegranskat)abstract
- Rapid Arctic warming drives profound change in the marine environment that have significant socio-economic impacts within the Arctic and beyond, including climate and weather hazards, food security, transportation, infrastructure planning and resource extraction. These concerns drive efforts to understand and predict Arctic environmental change and motivate development of an Arctic Region Component of the Global Ocean Observing System (ARCGOOS) capable of collecting the broad, sustained observations needed to support these endeavors. This paper provides a roadmap for establishing the ARCGOOS. ARCGOOS development must be underpinned by a broadly endorsed framework grounded in high-level policy drivers and the scientific and operational objectives that stem from them. This should be guided by a transparent, internationally accepted governance structure with recognized authority and organizational relationships with the national agencies that ultimately execute network plans. A governance model for ARCGOOS must guide selection of objectives, assess performance and fitness-to-purpose, and advocate for resources. A requirements-based framework for an ARCGOOS begins with the Societal Benefit Areas (SBAs) that underpin the system. SBAs motivate investments and define the system's science and operational objectives. Objectives can then be used to identify key observables and their scope. The domains of planning/policy, strategy, and tactics define scope ranging from decades and basins to focused observing with near real time data delivery. Patterns emerge when this analysis is integrated across an appropriate set of SBAs and science/operational objectives, identifying impactful variables and the scope of the measurements. When weighted for technological readiness and logistical feasibility, this can be used to select Essential ARCGOOS Variables, analogous to Essential Ocean Variables of the Global Ocean Observing System. The Arctic presents distinct needs and challenges, demanding novel observing strategies. Cost, traceability and ability to integrate region-specific knowledge have to be balanced, in an approach that builds on existing and new observing infrastructure. ARCGOOS should benefit from established data infrastructures following the Findable, Accessible, Interoperable, Reuseable Principles to ensure preservation and sharing of data and derived products. Linking to the Sustaining Arctic Observing Networks (SAON) process and involving Arctic stakeholders, for example through liaison with the International Arctic Science Committee (IASC), can help ensure success.
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| 11. |
- Starkweather, Sandy, et al.
(författare)
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Sustaining Arctic Observing Networks’ (SAON) Roadmap for Arctic Observing and Data Systems (ROADS)
- 2021
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Ingår i: Arctic. - : The Arctic Institute of North America. - 0004-0843 .- 1923-1245. ; 74:Suppl. 1, s. 56-68
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Tidskriftsartikel (refereegranskat)abstract
- Arctic observing and data systems have been widely recognized as critical infrastructures to support decision making and understanding across sectors in the Arctic and globally. Yet due to broad and persistent issues related to coordination, deployment infrastructure and technology gaps, the Arctic remains among the most poorly observed regions on the planet from the standpoint of conventional observing systems. Sustaining Arctic Observing Networks (SAON) was initiated in 2011 to address the persistent shortcomings in the coordination of Arctic observations that are maintained by its many national and organizational partners. SAON set forth a bold vision in its 2018 – 28 strategic plan to develop a roadmap for Arctic observing and data systems (ROADS) to specifically address a key gap in coordination efforts—the current lack of a systematic planning mechanism to develop and link observing and data system requirements and implementation strategies in the Arctic region. This coordination gap has hampered partnership development and investments toward improved observing and data systems. ROADS seeks to address this shortcoming through generating a systems-level view of observing requirements and implementation strategies across SAON’s many partners through its roadmap. A critical success factor for ROADS is equitable participation of Arctic Indigenous Peoples in the design and development process, starting at the process design stage to build needed equity. ROADS is both a comprehensive concept, building from a societal benefit assessment approach, and one that can proceed step-wise so that the most imperative Arctic observations—here described as shared Arctic variables (SAVs)—can be rapidly improved. SAVs will be identified through rigorous assessment at the beginning of the ROADS process, with an emphasis in that assessment on increasing shared benefit of proposed system improvements across a range of partnerships from local to global scales. The success of the ROADS process will ultimately be measured by the realization of concrete investments in and well-structured partnerships for the improved sustainment of Arctic observing and data systems in support of societal benefit.
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| 12. |
- Tronstad, Stein, et al.
(författare)
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Alignment of Polar Data Policies - Recommended Principles
- 2021
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This document presents a basis for alignment of polar data policies, notably the policies and statements of the Scientific Committee on Antarctic Research (SCAR), the International Arctic Science Committee (IASC), the Sustaining Arctic Observing Networks (SAON) initiative, the Arctic Spatial Data Infrastructure, and the Southern Ocean Observing System (SOOS). The document examines the state and recent developments of global and important regional data policies, as well as technological and institutional developments that should or might be considered when forming new polar data policies. Based on this examination, we conclude by identifying a number of data management principles that can be regarded as essential to the management of polar research data and can be incorporated in all polar data policies in such a way that they are aligned with each other and with overarching global and regional data policies.
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