Thaw Subsidence in Undisturbed Tundra Landscapes, Barrow, Alaska, 1962–2015

Abstract

In some regions underlain by ice‐rich permafrost, a consistent, long‐term increase in ALT under changing climatic conditions is not supported by observations. The apparent lack of ALT may be attributed to soil consolidation from thawing of the uppermost ice‐rich permafrost and subsidence of the ground surface. Four plots established in 1962 at Barrow, Alaska, were re‐instrumented in 2003 and surveyed annually using differential GPS technology, accompanied by active‐layer probing. Elevation change from 1962 to 2003 was within the interannual variability of the 2003–15 period, indicating net stability in the area. Over the 2003–15 period, however, all four plots experienced subsidence trends of 0.4–1.0 cm/year, resulting in a net elevation change of 8–15 cm. Warmer winters and increased snow depth during this period decreased the potential for frost heave. Warmer summers resulted in thaw penetration into the ice‐rich transient layer and ice wedges, leading to the net subsidence in recent years. Copyright © 2016 John Wiley & Sons, Ltd.

Decadal changes of surface elevation over permafrost area estimated using reflected GPS signals

“…We generate a time series of daily surface elevation changes on snow-free days over 12 summers. We will show that our observed interannual and decadal elevation changes match well with the GPS campaign observations from Streletskiy et al (2017) at a nearby site.…”

“…In areas where the near-surface permafrost is ice-rich, thermokarst processes could initiate at local scales upon thawing, causing abrupt and deep thaw as well as strong and irregular surface subsidence (Jorgenson, 2013). Recent observations from campaign GPS and InSAR reveal that thaw subsidence due to permafrost degradation can also occur gradually (a few millimeters per year) and relatively homogenously at regional scales (Liu et al, 2010;Shiklomanov et al, 2013;Streletskiy et al, 2017).…”

“…4.2 and 5.2 for the data processing method and results, respectively). We also use the daily vertical positions of the GPS receiver as a secondary data set, for two purposes: (1) to illustrate the magnitude of solid earth movement in the vertical direction and (2) to correct for the solid earth contribution from the GPS campaign results of Streletskiy et al (2017) so that we can directly compare theirs with our GPS-IR results (see more in Sect. 4.3).…”

“…Placing the GPS antenna on the top of specially designed tubes, they measured the surface vertical positions in the summers of 2001 and 2002 at two sites in the Kuparuk River basin, Alaska. The Circumpolar Active Layer Monitoring (CALM) program adopted the same protocol and conducted decade-long GPS campaigns at the end of thaw seasons in three continuous permafrost areas in northern Alaska (Shiklomanov et al, 2013;Streletskiy et al, 2017). However, these campaigns have been only conducted annually in mid-or late August, and thus do not allow one to measure seasonal changes.…”

Terrestrial laser scanning for quantifying small-scale vertical movements of the ground surface in Artic permafrost regions

“…Little et al, 2003;Shiklomanov et al, 2013;Beck et al, 2015;Streletskiy et al, 2016) or thaw-tubes (e.g. Nixon et al, 2003;Short et al, 2014).…”