A distributed temperature profiling method for assessing spatial variability in ground temperatures in a discontinuous permafrost region of Alaska

Emmanuel Léger, Baptiste Dafflon, Yves Robert, Craig Ulrich, John E. Peterson, Sébastien C. Biraud, Vladimir E. Romanovsky, Susan S. Hubbard

Research output: Contribution to journalArticlepeer-review

28 Scopus citations

Abstract

Soil temperature has been recognized as a property that strongly influences a myriad of hydro-biogeochemical processes and reflects how various properties modulate the soil thermal flux. In spite of its importance, our ability to acquire soil temperature data with high spatial and temporal resolution and coverage is limited because of the high cost of equipment, the difficulties of deployment, and the complexities of data management. Here we propose a new strategy that we call distributed temperature profiling (DTP) for improving the characterization and monitoring near-surface thermal properties through the use of an unprecedented number of laterally and vertically distributed temperature measurements. We developed a prototype DTP system, which consists of inexpensive, low-impact, low-power, and vertically resolved temperature probes that independently and autonomously record soil temperature. The DTP system concept was tested by moving sequentially the system across the landscape to identify near-surface permafrost distribution in a discontinuous permafrost environment near Nome, Alaska, during the summertime. Results show that the DTP system enabled successful acquisition of vertically resolved profiles of summer soil temperature over the top 0.8 m at numerous locations. DTP also enabled high-resolution identification and lateral delineation of near-surface permafrost locations from surrounding zones with no permafrost or deep permafrost table locations overlain by a perennially thawed layer. The DTP strategy overcomes some of the limitations associated with - and complements the strengths of - borehole-based soil temperature sensing as well as fiber-optic distributed temperature sensing (FO-DTS) approaches. Combining DTP data with co-located topographic and vegetation maps obtained using unmanned aerial vehicle (UAV) and electrical resistivity tomography (ERT) data allowed us to identify correspondences between surface and subsurface property distribution and in particular between topography, vegetation, shallow soil properties, and near-surface permafrost. Finally, the results highlight the considerable value of the newly developed DTP strategy for investigating the significant variability in and complexity of subsurface thermal and hydrological regimes in discontinuous permafrost regions.

Original languageEnglish
Pages (from-to)2853-2867
Number of pages15
JournalCryosphere
Volume13
Issue number11
DOIs
StatePublished - Nov 7 2019
Externally publishedYes

Funding

We acknowledge the assistance of ToddWood, Paul Cook, and Alejandro Morales of the Geoscience Measurement Facility (GMF) at Lawrence Berkeley National Laboratory for building the DTP prototype system. The probe sleeve and filling material were partly influenced by the work of Bill Cable (UAF, Alaska). This research has been supported by the Office of Biological and Environmental Research in the DOE Office of Science (grant no. DE-AC02-05CH11231). Financial support. This research has been supported by the Office of Biological and Environmental Research in the DOE Office of Science (grant no. DE-AC02-05CH11231).

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