Ice thickness and isostatic imbalances in the Ross Embayment, West Antarctica: model results
Ice thickness and isostatic imbalances in the Ross Embayment, West Antarctica: model results
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南极洲西部罗斯海湾的冰厚度和均衡失衡：模型结果
DOI：
10.1016/j.gloplacha.2003.09.005
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发表时间：
2004
影响因子：
3.9
通讯作者：
R. Alley
中科院分区：
文献类型：
--
作者：
B. Parizek;R. Alley
热机械流线模拟表明，南极洲西部的六海岸冰川只经历了很小的去冰川厚度变化，变薄的速度快于其海床均衡上升的速度，并且可以继续退缩。O(100)m的厚度变化是通过最后一次冰川旋回在现代接地线上模拟的。随着末次冰期最大值(LGM)的升温，累积速率的增加导致现代接地线的最大模拟厚度变化约为8ka。理想化的均衡模拟支持将冰盖模型耦合到下面的弹性岩石圈和松弛软流圈基岩模型。在上一次冰川周期中，冰和基岩之间的动态相互作用表明，均衡反弹在现代接地线上抬高冰盖的速度快于海平面上升淹没冰盖的速度。虽然这本身可能会导致接地线重新推进，但冰流被模拟为对最近温度、积累率和基本过程的变化做出更快的反应，而不是对基岩海拔和/或海平面波动做出反应。以前基于对冰流行为的热控制的结果[Parizek等人，2002年：地球物理研究快报29(2002)；Parizek等人，2003：冰川年鉴36(2003)251]支持这样的观点，即在后退的接地线上的冰流变薄可能会继续下去。虽然结果显示还剩下几十米的反弹，但陆基和空基观测将有助于限制这一级别，并可能对揭示过去的冰载历史和未来冰盖的稳定性产生影响。
Thermomechanical flowline simulations indicate that the Siple Coast ice streams of West Antarctica have experienced only small deglacial thickness changes, are thinning more rapidly than their beds are rising isostatically, and can continue to retreat. Thickness changes of O (100)m are modelled at the modern grounding line through the last glacial cycle. The accumulation-rate increase accompanying warming out of the last glacial maximum (LGM) leads to a maximum simulated thickness change at the modern grounding line approximately 8 ka. Idealized isostatic simulations support coupling the ice-sheet model to an underlying elastic-lithosphere and relaxed-asthenosphere bedrock model. Dynamic interactions between ice and bedrock over the last glacial cycle indicate that isostatic rebound is raising the ice sheet at the modern grounding line faster than the rising sea level is submerging it. While, in and of itself, this could potentially lead to a grounding-line re-advance, ice flow is modelled to respond to recent changes in temperature, accumulation rate, and basal processes more rapidly than it does to bedrock-elevation and/or sea-level fluctuations. Previous results based on thermal controls on ice-stream behavior [Parizek et al., 2002: Geophysical Research Letters 29 (2002); Parizek et al., 2003: Annals of Glaciology 36 (2003) 251] support the view that thinning of the ice streams at the retreating grounding line will likely continue. While results indicate an additional few tens of meters of rebound remaining, land- and air-based observations will help constrain this magnitude with potential implications for uncovering past ice-loading history and future ice-sheet stability.