Temperature distribution and thermal anomalies along a flowline of the Greenland ice sheet
Temperature distribution and thermal anomalies along a flowline of the Greenland ice sheet
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DOI：
10.3189/2015aog70a945
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发表时间：
2015-01-01
影响因子：
2.9
通讯作者：
Harper, Joel T.
中科院分区：
文献类型：
--
作者：
Harrington, Joel A.;Humphrey, Neil F.;Harper, Joel T.
格陵兰冰盖（GrIS）的冰川和基础温度数据是稀疏的，主要限于深内部网站和冰流，消融区内冰的热状态提供了一个不完整的代表。在这里，我们提出了11个温度分布在5个站点沿着34公里的西格陵兰东西样带。这些剖面图描述了沿出油管沿着的冰温以及紧密间隔的钻孔之间的局部温度变化。温带基底层是目前在所有的配置文件中，增加厚度的流动方向，在那里它扩大从类似的3%的冰高度最远的内陆到100%的边缘。温带厚度的增长是不一致的模拟热贡献应变加热，热传导，和温带层的垂直延伸。我们认为，基底裂隙，促进水压力或附近的冰覆盖层压力，是负责观察到的大温带冰厚度。51-85米深处的高温扭结可能是冰盖上部分充水裂隙热影响的残余。密集的钻孔之间陡峭的水平温度梯度表明最近的热影响的冰臼。这些配置文件表明，融化水的能力，迅速改变冰的温度在消融区内的所有深度。
Englacial and basal temperature data for the Greenland ice sheet (GrIS) are sparse and mostly limited to deep interior sites and ice streams, providing an incomplete representation of the thermal state of ice within the ablation zone. Here we present 11 temperature profiles at five sites along a 34 km east west transect of West Greenland. These profiles depict ice temperatures along a flowline and local temperature variations between closely spaced boreholes. A temperate basal layer is present in all profiles, increasing in thickness in the flow direction, where it expands from similar to 3% of ice height furthest inland to 100% at the margin. Temperate thickness growth is inconsistent with modeled heat contributions from strain heating, heat conduction, and vertical extension of the temperate layer. We suggest that basal crevassing, facilitated by water pressures at or near ice overburden pressure, is responsible for the large temperate ice thicknesses observed. High-temperature kinks at 51-85 m depth are likely remnants from the thermal influence of partially water-filled crevasses up ice sheet. Steep horizontal temperature gradients between closely grouped boreholes suggest the recent thermal influence of a moulin. These profiles demonstrate the ability of meltwater to rapidly alter ice temperatures at all depths within the ablation zone.