Tidal flexure at ice shelf margins
Tidal flexure at ice shelf margins
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冰架边缘的潮汐弯曲
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发表时间：
1995
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通讯作者：
D. Vaughan
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作者：
D. Vaughan
铰链区容纳了随海潮移动的浮冰架和不随海潮移动的搁浅冰原之间的不同潮汐运动。利用全球定位系统的运动学方法对南极Rutford冰流和Ronne冰架进行观测，首次获得了冰盖铰链区的连续潮汐位移剖面。这些潮汐位移曲线的形式表明，采用参数空间优化技术可以拟合弹性梁模型。模型将观测到的潮汐偏转廓线拟合在5 cm以内，与观测不确定度相近。然后，同样的模型和参数拟合技术成功地应用于来自南极洲多克冰架、巴赫冰架和埃克斯特罗姆冰架以及格陵兰岛雅各布港冰川的各种其他已发表和未发表的潮汐位移数据。我的结论是，弹性模量单一值（0.88±0.35 GPa）的弹性梁模型充分描述了几乎所有的数据，因此可以有效地应用于其他地方。早期基于粘性或瞬态蠕变流变学对冰架铰链带潮汐耗散的研究表明，全球潮汐能量耗散的30%可能发生在冰架铰链带。然而，这项研究表明，弹性流变学可能同样合适，在这种情况下，对潮汐能耗散的估计过高。
Hinge zones accommodate the differential tidal movement between floating ice shelves, which move with the sea tide, and grounded ice sheets, which do not. Observations on Rutford Ice Stream and Ronne Ice Shelf, Antarctica, using the kinematic method of Global Positioning System, have yielded the first continuous tidal displacement profiles from an ice sheet hinge zone. The form of these tidal displacement profiles indicates that the flexure can be fit to an elastic beam model using a parameter space optimization technique. The model matches the observed tidal deflection profile to within 5 cm which is similar to the observational uncertainty. The same model and parameter fitting technique is then successfully applied to various other published and unpublished tidal displacement data from Doake Ice Rumples, Bach Ice Shelf, and Ekstrom Ice Shelf, Antarctica, and Jakobshavns Glacier, Greenland. I conclude that the elastic beam model with a single value of the elastic modulus (0.88±0.35 GPa) adequately describes almost all the data and so can usefully be applied elsewhere. Earlier studies of tidal dissipation in ice shelf hinge zones, based on a viscous or transient creep rheology, showed that perhaps 30% of global tidal energy dissipation could be occurring in ice shelf hinge zones. This study suggests, however, that an elastic rheology may be equally appropriate, in which case this estimation of the tidal energy dissipation is excessively high.