Seasonal and interannual variabilities in terminus position, glacier velocity, and surface elevation at Helheim and Kangerlussuaq Glaciers from 2008 to 2016
Seasonal and interannual variabilities in terminus position, glacier velocity, and surface elevation at Helheim and Kangerlussuaq Glaciers from 2008 to 2016
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DOI：
10.1002/2016jf004133
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发表时间：
2017-09-01
影响因子：
3.9
通讯作者：
Krieger, L.
中科院分区：
文献类型：
--
作者：
Kehrl, L. M.;Joughin, I.;Krieger, L.
格陵兰冰川对海洋和大气变化的动态响应在空间和时间上都是不同的。虽然其中一些变化可能与区域气候信号有关，但冰川的几何形状似乎也很重要。在这项研究中，我们调查了2008年至2016年格陵兰东南部Helheim和Kangerlussuaq冰川季节性和年际演变的环境和几何控制，结合全年，卫星测量终点位置，冰川速度和表面高程。在这段时间里，赫尔海姆保持相对稳定，有一个轻微接地的终端，而康克鲁斯瓦格继续失去质量，因为它的接地线撤退到更深的水域。到2011年夏天，康克鲁斯瓦格的接地线已经退缩到较浅的水域，冰川有一个类似5公里长的漂浮冰舌。我们还观察到两个冰川表面速度和海拔的季节性变化。在黑尔海姆，季节性加速和动态变薄发生在夏末，当终点站是最撤退。在Kangerlussuaq，我们观察到夏季加速由于表面融化引起的基础润滑和冬季加速由于冰架撤退。我们认为，Helheim和Kangerlussuaq表现出不同的季节性时间尺度上，由于其终端附近的浮冰，这影响了冰山产犊行为的空间范围的差异。鉴于季节性加速和动态变薄可以改变这种空间范围，这些变化可能对了解这些和其他格陵兰岛冰川的长期演变很重要。
The dynamic response of Greenland tidewater glaciers to oceanic and atmospheric change has varied both spatially and temporally. While some of this variability is likely related to regional climate signals, glacier geometry also appears to be important. In this study, we investigated the environmental and geometric controls on the seasonal and interannual evolution of Helheim and Kangerlussuaq Glaciers, Southeast Greenland, from 2008 to 2016, by combining year-round, satellite measurements of terminus position, glacier velocity, and surface elevation. While Helheim remained relatively stable with a lightly grounded terminus over this time period, Kangerlussuaq continued to lose mass as its grounding line retreated into deeper water. By summer 2011, Kangerlussuaq's grounding line had retreated into shallower water, and the glacier had an similar to 5km long floating ice tongue. We also observed seasonal variations in surface velocity and elevation at both glaciers. At Helheim, seasonal speedups and dynamic thinning occurred in the late summer when the terminus was most retreated. At Kangerlussuaq, we observed summer speedups due to surface-melt-induced basal lubrication and winter speedups due to ice-shelf retreat. We suggest that Helheim and Kangerlussuaq behaved differently on a seasonal timescale due to differences in the spatial extent of floating ice near their termini, which affected iceberg-calving behavior. Given that seasonal speedups and dynamic thinning can alter this spatial extent, these variations may be important for understanding the long-term evolution of these and other Greenland tidewater glaciers.