Thermodynamics of a fast-moving Greenlandic outlet glacier revealed by fiber-optic distributed temperature sensing.

• Main Authors: Law, Robert, Christoffersen, Poul, Hubbard, Bryn, Doyle, Samuel H, Chudley, Thomas R, Schoonman, Charlotte M, Bougamont, Marion, des Tombe, Bas, Schilperoort, Bart, Kechavarzi, Cedric, Booth, Adam, Young, Tun Jan
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Association for the Advancement of Science (AAAS) 2021
• Subjects: 37 Earth Sciences; 3709 Physical Geography and Environmental Geoscience; 3705 Geology; Greenland; Kujalleq; glacier; greenlandic; Sermeq Kujalleq
• Online Access: https://www.repository.cam.ac.uk/handle/1810/322796; https://doi.org/10.17863/CAM.70252

Measurements of ice temperature provide crucial constraints on ice viscosity and the thermodynamic processes occurring within a glacier. However, such measurements are presently limited by a small number of relatively coarse-spatial-resolution borehole records, especially for ice sheets. Here, we advance our understanding of glacier thermodynamics with an exceptionally high-vertical-resolution (~0.65 m), distributed-fiber-optic temperature-sensing profile from a 1043-m borehole drilled to the base of Sermeq Kujalleq (Store Glacier), Greenland. We report substantial but isolated strain heating within interglacial-phase ice at 208 to 242 m depth together with strongly heterogeneous ice deformation in glacial-phase ice below 889 m. We also observe a high-strain interface between glacial- and interglacial-phase ice and a 73-m-thick temperate basal layer, interpreted as locally formed and important for the glacier's fast motion. These findings demonstrate notable spatial heterogeneity, both vertically and at the catchment scale, in the conditions facilitating the fast motion of marine-terminating glaciers in Greenland. European Union's Horizon 2020 (Grant 683043)