Basal terraces on melting ice shelves
Basal terraces on melting ice shelves
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DOI：
10.1002/2014gl060618
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发表时间：
2014-08-16
影响因子：
5.2
通讯作者：
Steffen, Konrad
中科院分区：
文献类型：
--
作者：
Dutrieux, Pierre;Stewart, Craig;Steffen, Konrad
海水融化了南极和格陵兰冰川的边缘，预计单个冰川的响应及其冰架的完整性将取决于融化的空间分布。与松岛冰川（西南极洲）和彼得曼冰川（格陵兰）相关的冰架底部具有相似的几何形状，包括沿冰流方向和横跨冰流方向延伸的千米宽、数百米高的水道。这些水道因海洋融化而扩大，同时也对海洋融化起到限制作用。对冰架底部地形的最新米级观测揭示了奇特的冰川地貌。水道侧翼并不平滑，而是呈阶梯状，数百米宽的平坦阶地被5 - 50米高的陡壁分隔开来。研究表明，融化受到这种几何形状的调节：每个阶地的融化速率恒定，但从一个阶地到下一个阶地会发生变化，在约45度倾斜的陡壁上融化速率大幅加快。因此，融化本质上是不均匀的，很可能与冰 - 海边界层的分层有关，这对当前冰架 - 海洋相互作用模型构成了挑战。
Ocean waters melt the margins of Antarctic and Greenland glaciers, and individual glaciers' responses and the integrity of their ice shelves are expected to depend on the spatial distribution of melt. The bases of the ice shelves associated with Pine Island Glacier (West Antarctica) and Petermann Glacier (Greenland) have similar geometries, including kilometer-wide, hundreds-of-meter high channels oriented along and across the direction of ice flow. The channels are enhanced by, and constrain, oceanic melt. New meter-scale observations of basal topography reveal peculiar glaciated landscapes. Channel flanks are not smooth, but are instead stepped, with hundreds-of-meters-wide flat terraces separated by 5-50m high walls. Melting is shown to be modulated by the geometry: constant across each terrace, changing from one terrace to the next, and greatly enhanced on the similar to 45 degrees inclined walls. Melting is therefore fundamentally heterogeneous and likely associated with stratification in the ice-ocean boundary layer, challenging current models of ice shelf-ocean interactions.