The role of ice stream dynamics in deglaciation
The role of ice stream dynamics in deglaciation
复制标题
冰流动力学在冰消过程中的作用
DOI：
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发表时间：
2016
期刊：
影响因子：
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通讯作者：
E. Tziperman
中科院分区：
文献类型：
--
作者：
A. Robel;E. Tziperman
自中更新世过渡以来，冰川消退仅发生在冰盖变大并经历几次岁差和岁差循环之后，这表明大冰盖比小冰盖对米兰科维奇强迫更敏感。观测和模型模拟表明，劳伦泰德冰盖冰流的发展在冰川消退中发挥了迄今未知的作用。在这项研究中，我们提出了一种机制，冰流可能会增强冰川消退，使大冰盖更敏感的米兰科维奇强迫。我们使用一个理想化的配置的平行冰盖模式，允许冰流的形成。当冰盖很大，冰流充分发展时，平衡线高度的向上移动，与米兰科维奇强迫相当，导致快速消融，而同样的移动适用于没有完全形成冰流的冰盖，导致冰盖持续增长或缓慢消融。具有显著流动行为的冰盖的快速消融是由冰流加速以及伴随的低海拔产犊和表面融化的增强引起的。冰流加速最终是冰表面变陡和冰流起始区驱动应力增加的结果，这是由于表面质量平衡对海拔的依赖。这些冰盖模拟符合地貌观测的广泛特征，并增加了冰流动力学，这是从以前的模型研究冰川消退。
Since the mid‐Pleistocene transition, deglaciation has occurred only after ice sheets have grown large while experiencing several precession and obliquity cycles, indicating that large ice sheets are more sensitive to Milankovitch forcing than small ice sheets are. Observations and model simulations suggest that the development of ice streams in the Laurentide Ice Sheet played an as yet unknown role in deglaciations. In this study, we propose a mechanism by which ice streams may enhance deglaciation and render large ice sheets more sensitive to Milankovitch forcing. We use an idealized configuration of the Parallel Ice Sheet Model that permits the formation of ice streams. When the ice sheet is large and ice streams are sufficiently developed, an upward shift in equilibrium line altitude, commensurate with Milankovitch forcing, results in rapid deglaciation, while the same shift applied to an ice sheet without fully formed ice streams results in continued ice sheet growth or slower deglaciation. Rapid deglaciation in ice sheets with significant streaming behavior is caused by ice stream acceleration and the attendant enhancement of calving and surface melting at low elevations. Ice stream acceleration is ultimately the result of steepening of the ice surface and increased driving stresses in ice stream onset zones, which come about due to the dependence of surface mass balance on elevation. These ice sheet simulations match the broad features of geomorphological observations and add ice stream dynamics that are missing from previous model studies of deglaciation.
影响因子：
12.1
作者：
M. Margold;C. Stokes;C. Clark
通讯作者：
M. Margold;C. Stokes;C. Clark
快速流动的出口冰川和冰流向内陆迁移的模型研究
影响因子：
3.4
作者：
Price, Stephen F.;Conway, Howard;Waddington, Edwin D.;Bindschadler, Robert A.
通讯作者：
Bindschadler, Robert A.