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
Scott Polar Research Institute, University of Cambridge, Cambridge, UK.
Centre for Glaciology, Aberystwyth University, Aberystwyth, UK.
Sci Adv. 2021 May 14;7(20). doi: 10.1126/sciadv.abe7136. Print 2021 May.
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.
冰温测量为冰的粘度以及冰川内部发生的热力学过程提供了关键限制条件。然而，目前此类测量受到数量较少且空间分辨率相对较低的钻孔记录的限制，特别是对于冰盖而言。在此，我们通过格陵兰岛 Sermeq Kujalleq（斯托尔冰川）底部钻至 1043 米深处的一个钻孔所获取的具有超高垂直分辨率（约 0.65 米）的分布式光纤温度传感剖面，增进了我们对冰川热力学的理解。我们报告了在深度 208 至 242 米的间冰期冰层内存在大量但孤立的应变加热现象，以及在 889 米以下的冰期冰层中存在强烈的非均匀冰变形。我们还观测到了冰期和间冰期冰层之间的一个高应变界面以及一个 73 米厚的温带底部冰层，该冰层被解释为局部形成且对冰川的快速运动至关重要。这些发现表明，在促进格陵兰岛海洋型末端冰川快速运动的条件方面，无论是在垂直方向还是在集水区尺度上，都存在显著的空间异质性。
