Quantification of Surface Subsidence Using Real Time Kinematic GPS in Experimentally Warmed Permafrost

Heidi Rodenhizer, Northern Arizona University, hgr7@nau.edu (Presenter)
Marguerite Mauritz, Northern Arizona University, marguerite.mauritz@nau.edu
Susan Natali, Woods Hole Research Center, snatali@whrc.org
Emily Romano, Northern Arizona University, elr88@nau.edu
Elaine Pegoraro, Northern Arizona University, efp23@nau.edu
Meghan Taylor, Northern Arizona University, meghan.taylor@nau.edu
Temuulen Sankey, Northern Arizona University, temuulen.sankey@nau.edu
Edward Schuur, Northern Arizona University, ted.schuur@nau.edu

Permafrost soils contain twice as much Carbon (C) as is currently in the atmosphere and can be composed of a high proportion ice. As temperatures rise, ice loss in permafrost causes subsidence, while warmer soil temperatures cause the release of stored C to the atmosphere. In addition, subsidence has the potential to speed permafrost thaw when water accumulates in subsided areas and speeds heat absorption. Using real-time kinematic GPS, we tracked subsidence at a permafrost warming experiment from 2009-2016 near Healy, Alaska, at a site underlain by continuous permafrost within the discontinuous permafrost zone. Soil warming is achieved by the installation of snow fences that cause snow to drift on the leeward side in winter, providing insulation from cold Arctic air temperatures. Environmental variables such as water table depth (WTD), active layer thickness (ALT), and CO2 fluxes are measured on the control and warming sides of the fence. Additionally, soil moisture and thaw depth were collected along a transect twice in the summer of 2017 as ground-truthing for ABoVE flights. Over the course of the experiment in the warming plots, WTD decreased by 3 times, ALT doubled and CO2 fluxes increased compared to the control plots. At the beginning of the experiment in 2009, slope corrected warming and control plot elevation surfaces showed differences of < 0.7 m between lowest and highest values, with no discernable spatial pattern. By 2016, warming plot elevation surfaces were clearly lower than control plot elevation surfaces, with differences of nearly 1 m between lowest and highest values. Concurrent changes in WTD, ALT, and CO2 fluxes at the site indicate interactions between several soil environmental variables could impact CO2 fluxes. Future research will investigate the ability to model ALT using remotely sensed digital terrain models, NDVI, and soil moisture available through ABoVE and NEON products.

Poster Location ID: 114

Session Assigned: Permafrost and Hydrology