Pathways of ocean heat towards Pine Island and Thwaites grounding lines
Pathways of ocean heat towards Pine Island and Thwaites grounding lines
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DOI：
10.1038/s41598-019-53190-6
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发表时间：
2019-11-22
影响因子：
4.6
通讯作者：
Menemenlis, Dimitris
中科院分区：
文献类型：
--
作者：
Nakayama, Yoshihiro;Manucharyan, Georgy;Menemenlis, Dimitris
在阿蒙森海中，变性绕极深层水（mCDW）侵入冰架洞穴，导致冰架在冰盖接地线附近大量融化，加速冰流，并控制着未来南极对全球海平面上升贡献的速度。mCDW流向接地线的路径至关重要，因为它们直接控制着到达冰层的热量。然而，由于原位观测的稀缺以及海洋模型难以重现现有观测结果，对mCDW环流的真实呈现仍然具有挑战性。在这项研究中，我们使用了一个分辨率极高（水平网格间距200米，垂直网格间距10米）的海洋模型，该模型在南半球夏季条件下对陆架海和冰架下环境的解析与现有观测在定性上相符。我们证明，到达松岛和思韦茨接地线的水体遵循特定的、受地形限制的路线，所有路线都经过位于西经104度和南纬74.3度附近的一个相对较小的区域。冰架融化速率的时空变化主要由冰架下的洋流控制。我们的研究结果强调了准确和高分辨率的海洋测深以及冰下地形对于确定mCDW路径和冰架融化速率的重要性。
In the Amundsen Sea, modified Circumpolar Deep Water (mCDW) intrudes into ice shelf cavities, causing high ice shelf melting near the ice sheet grounding lines, accelerating ice flow, and controlling the pace of future Antarctic contributions to global sea level. The pathways of mCDW towards grounding lines are crucial as they directly control the heat reaching the ice. A realistic representation of mCDW circulation, however, remains challenging due to the sparsity of in-situ observations and the difficulty of ocean models to reproduce the available observations. In this study, we use an unprecedentedly high-resolution (200 m horizontal and 10 m vertical grid spacing) ocean model that resolves shelf-sea and sub-ice-shelf environments in qualitative agreement with existing observations during austral summer conditions. We demonstrate that the waters reaching the Pine Island and Thwaites grounding lines follow specific, topographically-constrained routes, all passing through a relatively small area located around 104 degrees W and 74.3 degrees S. The temporal and spatial variabilities of ice shelf melt rates are dominantly controlled by the sub-ice shelf ocean current. Our findings highlight the importance of accurate and high-resolution ocean bathymetry and subglacial topography for determining mCDW pathways and ice shelf melt rates.