Models and observational constraints for fast ice flow and marine ice sheet dynamics

格陵兰岛和南极洲西部的冰盖含有足够的淡水，足以使全球海平面上升约13米。目前，对于这些冰盖在预计的气候变化下会以多快的速度缩小，目前还没有可靠的预测，也无法准确预测未来海平面上升的速度。对冰盖行为的更好预测将需要在数值模型中更准确地表示一些物理过程。冰盖并不是均匀流动的，而是含有称为冰流的快速流动通道。这些冰流是如何形成、演化并最终再次关闭的，人们对此只有部分了解，涉及的许多物理问题也没有在冰盖模型中表现出来。同样，人们对控制冰盖边缘演化(从而控制其水平范围)的物理学也只有部分了解。特别是，格陵兰和南极冰盖的边缘在许多地方都是由冰开始漂浮并形成冰架的位置来定义的。目前的模型无法准确预测流经冰盖和冰架之间的这些交界处的冰的速度，这阻碍了估计未来海平面变化的努力。拟议的研究计划将针对当前冰盖模型中的这些弱点，通过解决涉及冰流流动和冰盖边缘演变的基本物理问题。该研究计划将采取双管齐下的方法，使用复杂的现代数学方法，结合来自一个新的现场计划的数据，得出用于数值模拟的改进的冰盖物理表示法。

The ice sheets of Greenland and West Antarctica contain sufficient fresh water to raise global sea levels by about 13 metres. At present, there are no reliable predictions of how fast these ice sheets may shrink under projected climate change, and the future rate of sea level rise cannot be forecast accurately. Better predictions of ice sheet behaviour will require a number of physical processes to be represented more accurately in numerical models. Ice sheets do not flow evenly, but contain channels of fast flow known as ice streams. How these ice streams form, evolve and ultimately shut down again is only partially understood, and much of the physics involved is not represented in currebt ice sheet models. Similarly, the physics that controls the evolution of the edges of ice sheets (and hence their horizontal extent) is only partially understood. In particular, the edges of the Greenland and Antarctic ice sheets are defined in many places by the location where ice begins to float and forms an ice shelf. The rate at which ice flows through these junctions between ice sheets and ice shelves cannot be predicted accurately by present models, hampering efforts to estimate future sea level changes. The proposed research program will target these weaknesses in current ice sheet models by addressing the fundamental physics involved in ice stream flow and in the evolution of the margins of ice sheets. The research program will take a two-pronged approach, using sophisticated modern mathematical methods in conjunction with data from a new field program to derive improved representation of ice sheet physics for use in numerical simulations.