The goal of this research is to constrain the influence of ice wedge polygon microtopography on near-surface ground temperatures. Ice wedge polygon microtopography is prone to rapid deformation in a changing climate, and cracking in the ice wedge depends on thermal conditions at the top of the permafrost; therefore, feedbacks between microtopography and ground temperature can shed light on the potential for future ice wedge cracking in the Arctic. We first report on a year of sub-daily ground temperature observations at 5 depths and 9 locations throughout a cluster of low-centered polygons near Prudhoe Bay, Alaska, and demonstrate that the rims become the coldest zone of the polygon during winter, due to thinner snowpack. We then calibrate a polygon-scale numerical model of coupled thermal and hydrologic processes against this dataset, achieving an RMSE of less than 1.1 °C between observed and simulated ground temperature. Finally, we conduct a sensitivity analysis of the model by systematically manipulating the height of the rims and the depth of the troughs and tracking the effects on ice wedge temperature. The results indicate that winter temperatures in the ice wedge are sensitive to both rim height and trough depth, but more sensitive to rim height. Rims act as preferential outlets of subsurface heat; increasing rim size decreases winter temperatures in the ice wedge. Deeper troughs lead to increased snow entrapment, promoting insulation of the ice wedge. The potential for ice wedge cracking is therefore reduced if rims are destroyed or if troughs subside, due to warmer conditions in the ice wedge. These findings can help explain the origins of secondary ice wedges in modern and ancient polygons. The findings also imply that the potential for re-establishing rims in modern thermokarst-affected terrain will be limited by reduced cracking activity in the ice wedges, even if regional air temperatures stabilize.
Abolt, Charles J., et al. "Microtopographic control on the ground thermal regime in ice wedge polygons." The Cryosphere (Online), vol. 12, no. 6, Jun. 2018. https://doi.org/10.5194/tc-12-1957-2018
Abolt, Charles J., Young, Michael H., Atchley, Adam L., & Harp, Dylan R. (2018). Microtopographic control on the ground thermal regime in ice wedge polygons. The Cryosphere (Online), 12(6). https://doi.org/10.5194/tc-12-1957-2018
Abolt, Charles J., Young, Michael H., Atchley, Adam L., et al., "Microtopographic control on the ground thermal regime in ice wedge polygons," The Cryosphere (Online) 12, no. 6 (2018), https://doi.org/10.5194/tc-12-1957-2018
@article{osti_1463489,
author = {Abolt, Charles J. and Young, Michael H. and Atchley, Adam L. and Harp, Dylan R.},
title = {Microtopographic control on the ground thermal regime in ice wedge polygons},
annote = {The goal of this research is to constrain the influence of ice wedge polygon microtopography on near-surface ground temperatures. Ice wedge polygon microtopography is prone to rapid deformation in a changing climate, and cracking in the ice wedge depends on thermal conditions at the top of the permafrost; therefore, feedbacks between microtopography and ground temperature can shed light on the potential for future ice wedge cracking in the Arctic. We first report on a year of sub-daily ground temperature observations at 5 depths and 9 locations throughout a cluster of low-centered polygons near Prudhoe Bay, Alaska, and demonstrate that the rims become the coldest zone of the polygon during winter, due to thinner snowpack. We then calibrate a polygon-scale numerical model of coupled thermal and hydrologic processes against this dataset, achieving an RMSE of less than 1.1 °C between observed and simulated ground temperature. Finally, we conduct a sensitivity analysis of the model by systematically manipulating the height of the rims and the depth of the troughs and tracking the effects on ice wedge temperature. The results indicate that winter temperatures in the ice wedge are sensitive to both rim height and trough depth, but more sensitive to rim height. Rims act as preferential outlets of subsurface heat; increasing rim size decreases winter temperatures in the ice wedge. Deeper troughs lead to increased snow entrapment, promoting insulation of the ice wedge. The potential for ice wedge cracking is therefore reduced if rims are destroyed or if troughs subside, due to warmer conditions in the ice wedge. These findings can help explain the origins of secondary ice wedges in modern and ancient polygons. The findings also imply that the potential for re-establishing rims in modern thermokarst-affected terrain will be limited by reduced cracking activity in the ice wedges, even if regional air temperatures stabilize.},
doi = {10.5194/tc-12-1957-2018},
url = {https://www.osti.gov/biblio/1463489},
journal = {The Cryosphere (Online)},
issn = {ISSN 1994-0424},
number = {6},
volume = {12},
place = {United States},
publisher = {European Geosciences Union},
year = {2018},
month = {06}}
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23); National Aeronautics and Space Administration (NASA) (United States)
Grant/Contract Number:
AC52-06NA25396
OSTI ID:
1463489
Report Number(s):
LA-UR-18-20029
Journal Information:
The Cryosphere (Online), Journal Name: The Cryosphere (Online) Journal Issue: 6 Vol. 12; ISSN 1994-0424
Next Generation Ecosystems Experiment - Arctic, Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (US); NGEE Arctic, Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)https://doi.org/10.5440/1236647
Next Generation Ecosystems Experiment - Arctic, Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (US); NGEE Arctic, Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)https://doi.org/10.5440/1240734
Institute, University Of Alaska Fairbanks, Geophysical Institute;University Of Alaska Fairbanks, Geophysical Institute;University Of Alaska Fairbanks, Geophysical Institute;University Of Alaska Fairbanks, Geophysical Institute;University Of Alaska Fairbanks, Geophysical Institute;University Of Alaska Fairbanks, Geophysical Institute;University Of Alaska Fairbanks, Geophysical Institute;University Of Alaska, Water And Environmental Research Center;University Of Alaska Fairbanks, Geophysical
