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TitleRADARSAT-2 D-InSAR for ground displacement in permafrost terrain, validation from Iqaluit Airport, Baffin Island, Canada
AuthorShort, N; LeBlanc, A -M; Sladen, W; Oldenborger, G; Mathon-Dufour, V; Brisco, B
SourceRemote Sensing of Environment vol. 141, 2014 p. 40-51,
Alt SeriesEarth Sciences Sector, Contribution Series 20130063
Mediapaper; on-line; digital
File formatpdf; html
NTS25N/10; 25N/15
AreaIqaluit; Baffin Island
Lat/Long WENS -69.0000 -68.5000 64.0000 63.5000
Subjectsgeophysics; surficial geology/geomorphology; remote sensing; satellite imagery; permafrost; freezing ground; ground ice; displacement; terrain analysis; terrain sensitivity; terrain types; RADARSAT-2; D-InSAR; Cenozoic; Quaternary
Illustrationslocation maps; tables; photographs; graphs
ProgramLand-based Infrastructure, Climate Change Geoscience
AbstractThe use of Differential Interferometric Synthetic Aperture Radar (D-InSAR) is rapidly gaining acceptance as a source of ground displacement information for permafrost regions. The accuracy of the information however, is still not well established. This paper uses a stack of RADARSAT-2 D-InSAR data to map seasonal ground displacement at the Iqaluit Airport, Baffin Island, Canada. The accuracy and information content of the D-InSAR products are evaluated with a variety of ground truth data. The D-InSAR derived seasonal ground displacement patterns align well with surficial geology units and reflect the thaw settlement characteristics of the sediments; they also identify localised displacement patterns in the vicinity of features such as ice wedges and frost cracks. Comparisonswith ground settlementmeasurements fromin-situ thaw tubes indicate sub-centimetre agreement in dry areas. In low lying wet areas however, subject to saturation and flooding, the D-InSAR stack significantly underestimates the true settlement, detecting only 3.7 cmof the 8.5 cmthaw tube measurement. The combination of high phase gradients and poor coherence over intermittently flooded surfaces makes it challenging to preserve reliable phase measurements in these areas. Information from electromagnetic surveys shows that some surface displacement is related to sub-surface conditions (b6 m depth), possibly conditions related to the presence and movement of water in the active layer and to a lesser extent, unfrozen water content within the permafrost.
Summary(Plain Language Summary, not published)
Satellite radar data can be carefully processed to reveal movement of the ground in permafrost areas. Patterns of movement are useful in understanding locations and causes of terrain instability and hence dangers to infrastructure. This paper uses field measurements to determine the accuracy of satellite derived maps of seasonal terrain stability in permafrost zones. In dry areas the accuracies are very good, between 0.4 and 1 cm, but in wet areas, surface flooding can complicate the signal. Wet areas are still correctly identified as unstable, but the accuracy is much reduced.