Seasonal InSAR Displacements Documenting the Active Layer Freeze and Thaw Progression in Central-Western Spitsbergen, Svalbard

• Published in: Remote Sensing
• Main Authors: Line Rouyet, Lin Liu, Sarah Marie Strand, Hanne Hvidtfeldt Christiansen, Tom Rune Lauknes, Yngvar Larsen
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2021
• Subjects: permafrost; active layer; InSAR; time series; ground displacement; ground temperature; Science; Q; Adventdalen; Kapp Linné; Ny-Ålesund; Svalbard; Ice; Ny Ålesund; Spitsbergen
• Online Access: https://doi.org/10.3390/rs13152977; https://doaj.org/article/6da6dbcbfd0f44fa96d4c40b81667eed

In permafrost areas, the active layer undergoes seasonal frost heave and thaw subsidence caused by ice formation and melting. The amplitude and timing of the ground displacement cycles depend on the climatic and ground conditions. Here we used Sentinel-1 Synthetic Aperture Radar Interferometry (InSAR) to document the seasonal displacement progression in three regions of Svalbard. We retrieved June–November 2017 time series and identified thaw subsidence maxima and their timing. InSAR measurements were compared with a composite index model based on ground surface temperature. Cyclic seasonal patterns are identified in all areas, but the timing of the displacement progression varies. The subsidence maxima occurred later on the warm western coast (Kapp Linné and Ny-Ålesund) compared to the colder interior (Adventdalen). The composite index model is generally able to explain the observed patterns. In Adventdalen, the model matches the InSAR time series at the location of the borehole. In Kapp Linné and Ny-Ålesund, larger deviations are found at the pixel-scale, but km or regional averaging improves the fit. The study highlights the potential for further development of regional InSAR products to represent the cyclic displacements in permafrost areas and infer the active layer thermal dynamics.