skip to main content

DOE PAGESDOE PAGES

Title: Microtopographic control on the ground thermal regime in ice wedge polygons

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.more » 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.« less
Authors:
ORCiD logo [1] ; ORCiD logo [2] ; ORCiD logo [3] ; ORCiD logo [3]
  1. Univ. of Texas, Austin, TX (United States). Dept. of Geological Sciences. Bureau of Economic Geology
  2. Univ. of Texas, Austin, TX (United States). Bureau of Economic Geology
  3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Report Number(s):
LA-UR-18-20029
Journal ID: ISSN 1994-0424
Grant/Contract Number:
AC52-06NA25396; C021199
Type:
Accepted Manuscript
Journal Name:
The Cryosphere (Online)
Additional Journal Information:
Journal Name: The Cryosphere (Online); Journal Volume: 12; Journal Issue: 6; Journal ID: ISSN 1994-0424
Publisher:
European Geosciences Union
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23); National Aeronautic and Space Administration (NASA)
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; Earth Sciences
OSTI Identifier:
1463489

Abolt, Charles J., Young, Michael H., Atchley, Adam L., and Harp, Dylan R.. Microtopographic control on the ground thermal regime in ice wedge polygons. United States: N. p., Web. doi:10.5194/tc-12-1957-2018.
Abolt, Charles J., Young, Michael H., Atchley, Adam L., & Harp, Dylan R.. Microtopographic control on the ground thermal regime in ice wedge polygons. United States. doi:10.5194/tc-12-1957-2018.
Abolt, Charles J., Young, Michael H., Atchley, Adam L., and Harp, Dylan R.. 2018. "Microtopographic control on the ground thermal regime in ice wedge polygons". United States. doi:10.5194/tc-12-1957-2018. https://www.osti.gov/servlets/purl/1463489.
@article{osti_1463489,
title = {Microtopographic control on the ground thermal regime in ice wedge polygons},
author = {Abolt, Charles J. and Young, Michael H. and Atchley, Adam L. and Harp, Dylan R.},
abstractNote = {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},
journal = {The Cryosphere (Online)},
number = 6,
volume = 12,
place = {United States},
year = {2018},
month = {6}
}