Diurnal lake-level cycles on ice shelves driven by meltwater input and ocean tidal tilt
Diurnal lake-level cycles on ice shelves driven by meltwater input and ocean tidal tilt
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DOI：
10.1017/jog.2019.98
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发表时间：
2020-01
影响因子：
3.4
通讯作者：
D. Macayeal;I. Willis;A. Banwell;G. Macdonald;B. Goodsell
中科院分区：
文献类型：
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作者：
D. Macayeal;I. Willis;A. Banwell;G. Macdonald;B. Goodsell
在南极洲麦克默多冰架上的冰上湖中观察到分米级的日深度循环。我们评估了两个可能的原因：（1）冰架的潮汐倾斜对底层海潮的响应，以及（2）融水输入的变化。我们发现后者是对我们的观察结果最有可能的解释。然而，我们并不排除潮汐倾斜是厘米级变化的来源，并指出其他较大的冰上湖泊系统，特别是那些经历更大幅度潮汐倾斜的冰架上的湖泊系统，例如威德尔海，可能具有由海潮驱动的深度循环。融水深度的昼夜循环更广泛的意义在于，在冰架薄、潮汐倾斜幅度高、融水径流率大的情况下，可能存在相关的弯曲应力，从而导致冰架破裂和不稳定。对于麦克默多冰架（约 20–50 m 厚度、约 1 m 潮汐幅度和约 10 cm 水深变化），这些应力总计达数十 kPa。
Diurnal depth cycles of decimeter scale are observed in a supraglacial lake on the McMurdo Ice Shelf, Antarctica. We evaluate two possible causes: (1) tidal tilt of the ice shelf in response to the underlying ocean tide, and (2) meltwater input variation. We find the latter to be the most likely explanation of our observations. However, we do not rule out tidal tilt as a source of centimeter scale variations, and point to the possibility that other, larger supraglacial lake systems, particularly those on ice shelves that experience higher amplitude tidal tilts, such as in the Weddell Sea, may have depth cycles driven by ocean tide. The broader significance of diurnal cycles in meltwater depth is that, under circumstances where the ice shelf is thin, tidal-tilt amplitudes are high, and meltwater runoff rates are large, there may be associated flexure stresses that can contribute to ice-shelf fracture and destabilization. For the McMurdo Ice Shelf (~20–50 m thickness, ~ 1 m tidal amplitude and ~10 cm water-depth variations), these stresses amount to several 10's of kPa.