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TitleMapping permafrost and terrain conditions by combining corrected DInSAR seasonal and inter-annual ground displacements
AuthorLeBlanc, A -M; Oldenborger, G A; Short, N
SourceCold Regions Engineering 2019: proceedings of the 18th International Conference on Cold Regions Engineering and the 8th Canadian Permafrost Conference; by Bilodeau, J -P (ed.); Nadeau, D F (ed.); Fortier, D (ed.); Conciatori, D (ed.); 2019 p. 616-624
Alt SeriesNatural Resources Canada, Contribution Series 20180445
PublisherAmerican Society of Civil Engineers
Mediaon-line; digital
File formatpdf (Adobe® Reader®)
ProgramClimate Change Geoscience, Permafrost
Released2019 08 01
AbstractDifferential interferometric synthetic aperture radar (DInSAR) is commonly used to assess thaw subsidence in permafrost regions. However, the method is vulnerable to noise, processing strategy, and other environmental processes. In this study, we present a post-processing correction method applied to DInSAR displacement maps over a study area near Rankin Inlet, Nunavut. The correction removes residual noise, and permits quantitative comparison between different DInSAR maps and other data. Our correction method does not require advanced InSAR processing, but requires the presence of stable bedrock outcrops uniformly distributed over the DInSAR scenes. Results show that the method successfully corrects for local errors without drastic deviation from uncorrected maps. By using corrected displacement maps from C-band (RADARSAT-2) and L-band (ALOS-2 PALSAR-2) satellites, we combine seasonal and inter-annual displacements to create a permafrost terrain map that describes current and short-term permafrost conditions. The permafrost terrain map also highlights areas where DInSAR results could preferentially be affected by soil moisture or flooded vegetation. For the Rankin Inlet area, the permafrost terrain map shows that permafrost is relatively stable, with localized high subsidence related to the melting of frost blisters and, to a lesser extent, the melting of segregated ground ice near top of permafrost.
Summary(Plain Language Summary, not published)
Thaw subsidence in permafrost regions is strongly linked to the ground ice content. More ground ice there is, more thaw subsidence there will be and, therefore, more sensitive will be the ground to climate change. Remote sensing is the only method to measure thaw subsidence over large areas. However, the results are affected by noise that limit our ability to quantitatively compare different results, from the same technique, for a given region. In this study, we describe a simple method to correct the residual noises, then we use the corrected results to build a permafrost map. The latter is the result of a combination between seasonal and inter-annual subsidence. It allows classifying soils according to their climate change sensitivity (degradation potential) and isolating certain areas affected by other processes than thaw subsidence.