论文标题
冰流形成
Ice stream formation
论文作者
论文摘要
冰流是冰盖中快速流动的冰乐队。我们基于耗散和基础滑动之间的积极反馈，研究它们的形成是自发模式形成的一个例子。我们的重点是依赖温度的亚较高滑动，在这种滑动下，更快的滑动速度会导致耗散增强，因此温度更高，进一步削弱了床，尽管我们还处理了在完全熔融床上运行的水力机械反馈机制。我们开发了一种新型的热机械模型，该模型在横向方向上捕获冰块量表物理学，同时假设流动沿主要下游方向浅。使用该模型，我们表明，稳定的时间模式的形成可以通过在嘈杂的基础条件的下游方向放大而发生，并且通常会导致建立一个明确定义的冰流，该冰流与狭窄的剪切边缘通过狭窄的缓慢流动的，基于冷的冰脊分开，在下游方向上冰流扩大。我们能够证明冷冰的下降是主要的稳定机制，并给出了模式形成的近似分析标准。
Ice streams are bands of fast-flowing ice in ice sheets. We investigate their formation as an example of spontaneous pattern formation, based on positive feedbacks between dissipation and basal sliding. Our focus is on temperature-dependent subtemperate sliding, where faster sliding leads to enhanced dissipation and hence warmer temperatures, weakening the bed further, although we also treat a hydromechanical feedback mechanism that operates on fully molten beds. We develop a novel thermomechanical model capturing ice-thickness scale physics in the lateral direction while assuming the the flow is shallow in the main downstream direction. Using that model, we show that formation of a steady-in-time pattern can occur by the amplification in the downstream direction of noisy basal conditions, and often leads to the establishment of a clearly-defined ice stream separated from slowly-flowing, cold-based ice ridges by narrow shear margins, with the ice stream widening in the downstream direction. We are able to show that downward advection of cold ice is the primary stabilizing mechanism, and give an approximate, analytical criterion for pattern formation.
