The Impacts of a Subglacial Discharge Plume on Calving, Submarine Melting, and Melange Mass Loss at Helheim Glacier, South East Greenland
The Impacts of a Subglacial Discharge Plume on Calving, Submarine Melting, and Melange Mass Loss at Helheim Glacier, South East Greenland
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DOI：
10.1029/2020jf005910
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发表时间：
2021-03-01
影响因子：
3.9
通讯作者：
Reeve, Dominic E.
中科院分区：
文献类型：
--
作者：
Everett, Alistair;Murray, Tavi;Reeve, Dominic E.
格陵兰冰盖的质量损失几乎有一半是通过海洋终止冰川的冰山崩解发生的。在这些海洋终端存在的浮力冰下排放羽流被认为是通过海底融化和底切增加质量损失，从而增加产犊率。羽流模型用于预测海底熔化和底切。然而，很少有观察结果可以检验这些关系。在这里，我们使用机载激光雷达从Helheim冰川，格陵兰东南部的终点测量隆起引起的表面上涌羽。我们使用这些测量来估计羽流排放率使用高分辨率，三维羽流模型。羽流的多年观测相比，记录从相机和冰震数据的产犊。我们没有发现任何证据表明，羽流的存在下，由其在表面的能见度，增加了主要的产犊事件的频率，也表明，直接由羽流排放驱动的终端的质量损失显着小于质量损失的主要产犊事件。结果表明，在深海终止冰川的直接羽驱动的质量损失的贡献可能小于在较浅的终端。
Almost half of the Greenland ice sheet's mass loss occurs through iceberg calving at marine terminating glaciers. The presence of buoyant subglacial discharge plumes at these marine termini are thought to increase mass loss both through submarine melting and by undercutting that consequently increases calving rates. Plume models are used to predict submarine melting and undercutting. However, there are few observations that allow these relationships to be tested. Here, we use airborne lidar from the terminus of Helheim Glacier, SE Greenland to measure the bulge induced at the surface by the upwelling plume. We use these measurements to estimate plume discharge rates using a high-resolution, three-dimensional plume model. Multiyear observations of the plume are compared to a record of calving from camera and icequake data. We find no evidence to suggest that the presence of a plume, determined by its visibility at the surface, increases the frequency of major calving events and also show that mass loss at the terminus driven directly by plume discharge is significantly less than mass loss from major calving events. The results suggest that the contribution of direct plume-driven mass loss at deep marine-terminating glaciers may be less than at shallower termini.