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The Cryosphere An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/tc-2018-2
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
12 Jan 2018
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal The Cryosphere (TC).
Microtopographic control on the ground thermal regime in ice wedge polygons
Charles J. Abolt1,2, Michael H. Young2, Adam L. Atchley3, and Dylan R. Harp3 1Department of Geological Sciences, The University of Texas at Austin, Austin, TX, USA
2Bureau of Economic Geology, The University of Texas at Austin, Austin, TX, USA
3Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM, USA
Abstract. The goal of this research is to constrain the influence of ice wedge polygon topography on near-surface ground temperatures. Because ice wedge polygon topography is prone to rapid change in a changing climate, and because cracking in the ice wedge depends on thermal conditions at the top of the permafrost, feedbacks between topography and ground temperature can shed light on the potential for future ice wedge cracking in the Arctic. We first report on a year of subdaily ground temperature observations at five depths and nine locations throughout a cluster of low-centered polygons near Prudhoe Bay, AK, 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 1.2 °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 deeper troughs lead to increased snow entrapment, promoting insulation of the ice wedge. Rims act as preferential outlets of subsurface heat; increasing rim size decreases winter temperatures in 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 reestablishing rims in modern thermokarst-affected terrain will be precluded by reduced cracking activity in the ice wedges, even if regional air temperatures stabilize.
Citation: Abolt, C. J., Young, M. H., Atchley, A. L., and Harp, D. R.: Microtopographic control on the ground thermal regime in ice wedge polygons, The Cryosphere Discuss., https://doi.org/10.5194/tc-2018-2, in review, 2018.
Charles J. Abolt et al.
Charles J. Abolt et al.
Charles J. Abolt et al.

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Short summary
We investigate the relationship between ice wedge polygon topography and near-surface ground temperatures, using a combination of field work and numerical modeling. We analyze a year-long record of ground temperature across a low-centered polygon, then demonstrate that lower rims and deeper troughs promote warmer conditions in the ice wedge in winter. This finding implies that ice wedge cracking and growth, which are driven by cold conditions, can be impeded by trough subsidence or rim erosion.
We investigate the relationship between ice wedge polygon topography and near-surface ground...
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