Seasonal Progression of Ground Displacement Identified with Satellite Radar Interferometry and the Impact of Unusually Warm Conditions on Permafrost at the Yamal Peninsula in 2016

Abstract

Ground subsidence monitoring by Synthetic Aperture Radar interferometry (InSAR) over Arctic permafrost areas is largely limited by long revisit intervals, which can lead to signal decorrelation. Recent satellite missions such as COSMO-Skymed (X-band) and Sentinel-1 (C-band) have comparably short time intervals of a few days. We analyze dense records of COSMO-Skymed from 2013 and 2016 and of Sentinel-1 from 2016, 2017, and 2018 for the unfrozen period over central Yamal (Russia). These years were distinct in environmental conditions and 2016 in particular was unusually warm. We evaluate the InSAR-derived displacement with in situ subsidence records, active-layer thickness measurements, borehole temperature records, meteorological data, C-band scatterometer records, and a land-cover classification based on Sentinel-1 and -2 data. Our results indicate that a comparison of seasonal thaw evolution between years is feasible after accounting for the early thaw data gap in InSAR time series (as a result of snow cover) through an assessment with respect to degree-days of thawing. Average rates of subsidence agree between in situ and Sentinel-1 (corrected for viewing geometry), with 3.9 mm and 4.3 mm per 100 degree-days of thaw at the test site. X-band and C-band records agree well with each other, including seasonal evolution of subsidence. The average displacement is more than twice in magnitude at the active-layer monitoring test site in 2016 compared to the other years. We further demonstrate that InSAR displacement can not only provide information on the magnitude of ground thaw but also on soil properties through analyses of seasonal evolution in extreme years.

Ground subsidence and heave over permafrost: hourly time series reveal interannual, seasonal and shorter-term movement caused by freezing, thawing and water movement

“…Especially at locations with permafrost, large amounts of ground ice can exist and its decay may have pronounced effects at the terrain surface (Shumskiy and Vtyurin, 1963;Mackay, 1970;Heginbottom, 1973). In recent decades, the interest in observation (Liu et al, 2010;Bartsch et al, 2019) and prediction (Hwang, 1976;Lee et al, 2014) of ground subsidence has been increasing along with the prevalence of ground-ice loss due to anthropogenic climate change.…”

Multi-Scale and Multi-Dimensional Time Series InSAR Characterizing of Surface Deformation over Shandong Peninsula, China

“…The advanced time series InSAR techniques have facilitated coastal land subsidence monitoring in many regions [1][2][3][4][5]21]. Moreover, the InSAR technique shows its potential in large-scale deformation monitoring, e.g., on a regional scale or national scale with the increased availability of free-of-charge and commercial SAR datasets [22][23][24]. Although the conventional ground-based methods including global positioning systems (GPS) and leveling can provide precise measurements, the lack of such measurements makes it difficult to verify the InSAR measurements.…”

Remote Sensing for Assessing Landslides and Associated Hazards

“…Among the case studies presented in this contribution, we can find landslides in periglacial environments, which are characterized by moderate slope terrain in morainal material where landslides are associated to the presence of ground ice, permafrost conditioned by freeze/thaw cycling (Lewkowicz 2007;Jorgenson and Grosse 2016;Lewkowicz and Way 2019). In such context, unconsolidated sediments currently frozen can be easily mobilized under exceptionally warm conditions, when the depth of the seasonal thaw layer exceeds normal conditions in such years (Bartsch et al 2019). The analysis of such landslides in permafrost notably is of particular importance in the Arctic, as landslides are proxies to understand the carbon cycle, as it has been demonstrated that carbon-rich landslides can even contribute to ocean acidification (Zolkos et al 2019).…”

“…Unconsolidated sediments are currently frozen but can be mobilized under exceptionally warm conditions. The depth of the seasonal thaw layer (active layer thickness-ALT) exceeds normal conditions in exceptionally warm years (Bartsch et al 2019). Ice lenses at the base of the active layer melt leading to high porewater pressures, a reduction in effective shear strength, and eventually slope failure.…”