Evolution of the subglacial drainage system beneath the Greenland Ice Sheet revealed by tracers
Evolution of the subglacial drainage system beneath the Greenland Ice Sheet revealed by tracers
复制标题
DOI：
10.1038/ngeo1737
复制
发表时间：
2013-03-01
影响因子：
18.3
通讯作者：
Hubbard, A.
中科院分区：
文献类型：
--
作者：
Chandler, D. M.;Wadham, J. L.;Hubbard, A.
格陵兰冰盖对气候变化的反应的预测在一定程度上受到冰盖床的融水润滑和冰流之间耦合的不确定性的限制（1-3）。这种不确定性主要是由于缺乏对冰盖底部水流特性的直接测量。以前的工作仅限于根据表面冰速度（4-7）和融水通量（8）的季节和空间变化进行间接观测。在这里，我们采用罗丹明和六氟化硫示踪剂，注入到排水系统在三个融化季节，观察冰下排水性能和格陵兰冰盖下的演变，从边缘57公里。示踪结果表明，从一个缓慢的，低效的排水系统，快速，高效的渠化排水系统的过程中的融化季节的演变。在更远的内陆，向高效排水的演变发生得更晚，也更慢。在距冰缘41公里或更远的地方建立了一条有效的水流路线，那里的冰厚约1公里。总的来说，我们的研究结果支持以前的解释排水系统的特点，从而验证了使用表面观测作为一种手段，调查基础过程。
Predictions of the Greenland Ice Sheet's response to climate change are limited in part by uncertainty in the coupling between meltwater lubrication of the ice-sheet bed and ice flow(1-3). This uncertainty arises largely from a lack of direct measurements of water flow characteristics at the bed of the ice sheet. Previous work has been restricted to indirect observations based on seasonal and spatial variations in surface ice velocities(4-7) and on meltwater flux(8). Here, we employ rhodamine and sulphur hexafluoride tracers, injected into the drainage system over three melt seasons, to observe subglacial drainage properties and evolution beneath the Greenland Ice Sheet, up to 57 km from the margin. Tracer results indicate evolution from a slow, inefficient drainage system to a fast, efficient channelized drainage system over the course of the melt season. Further inland, evolution to efficient drainage occurs later and more slowly. An efficient routing of water was established up to 41 km or more from the margin, where the ice is approximately 1 km thick. Overall, our findings support previous interpretations of drainage system characteristics, thereby validating the use of surface observations as a means of investigating basal processes.