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TitleInSAR maps: seasonal and inter-annual displacements in permafrost environments, case study for the Iqaluit area, Nunavut
AuthorLeBlanc, A -M; Short, N; Sladen, W; Oldenborger, G; Mathon-Dufour, V; Allard, M; L'Hérault, E
SourceArcticNet (ASM2013), programme; 2013 p. 76-77
Alt SeriesEarth Sciences Sector, Contribution Series 20140129
MeetingArcticNet 2013; Halifax; CA; December 9-13, 2013
Mediapaper; on-line; digital
File formatpdf
NTS25N/09; 25N/10; 25N/15; 25N/16
Lat/Long WENS -69.0000 -68.0000 64.0000 63.5000
Subjectssurficial geology/geomorphology; environmental geology; geophysics; permafrost; freezing ground; ground ice; ground temperatures; climate, arctic; climate; remote sensing; RADARSAT-2; SAR
ProgramLand-based Infrastructure, Climate Change Geoscience
LinksOnline - En ligne
AbstractIn recent years, interest in the use of Interferometric Synthetic Aperture Radar (InSAR) as a source of ground surface displacement information for natural and built permafrost environments has increased considerably. Among the available InSAR methods, conventional differential InSAR (D-InSAR) makes it possible to detect very small ground surface movement, on the order of centimetres, for every pixel over large coverage areas. As part of the Climate Change and Northern Development and Remote Sensing Science NRCan initiatives, D-InSAR data were acquired over three consecutive summers for the Iqaluit area, Nunavut. Scientists at the Canada Centre for Mapping and Earth Observation have been working to improve the processing of the InSAR data, while field validation has been undertaken in collaboration with scientists at the Geological Survey of Canada and a complementary project led by the Centre d¿études nordiques at the Iqaluit airport. RADARSAT-2 spotlight scenes with a resolution of approximately 1 m were used to create maps of seasonal ground surface displacement. These maps are interpreted based on a wide range of field observations including surficial material, permafrost characteristics, ground temperature, climate data and seasonal settlement measurements. Results show that the D-InSAR maps are slightly different from year to year, but overall displacement patterns do align very well with surficial geology units. Low displacement is statistically associated with bedrock and coarse sediments, while finer sediments, more likely to be ice-rich, show higher settlement. Within the same terrain unit, local surface and subsurface conditions can lead to different amounts of displacement. In general, displacement seen in seasonal data sets is caused by thawing of the active layer. However, in the seasonal maps, field observations also highlight areas of subsidence driven by long-term instability, for example, in areas of low-centre polygons due to the degradation of ice-rich permafrost. InSAR maps adapted for permafrost environments have the potential to provide useful geoscience information to support decision-making for existing or new infrastructure. In that context, results for built and natural environments are compared for the Iqaluit area. The information content, advantages and limitations of the results are discussed.
Summary(Plain Language Summary, not published)
Satellite radar data can be carefully processed to reveal movement of the ground in permafrost areas. These patterns of movement are useful in understanding patterns and causes of terrain instability and hence dangers to infrastructure. The talk will focus on ground data to validate the satellite derived maps of seasonal terrain stability in permafrost zones. Although some limitations exist in the interpretation of the results, the satellite data acquired over three consecutive summers for the Iqaluit area, Nunavut, show good agreement with the surficial geology.