Arctic Sea Ice Dynamics Using Experiments and Multi-scale Modelling

卫星和潜艇观测显示，北冰洋海冰正在迅速变薄。最近的计算机模拟表明，关于海冰出口到格陵兰海的预测对海冰覆盖力的处理高度敏感，在格陵兰海，海冰将在那里融化，形成一个浮力层，减弱向下涌流，从而降低墨西哥湾流北部范围的强度。海冰力的模型表达是不确定的，但应力主要是由海冰(宽100~10公里，厚几米)在垂直变形中相互重叠形成压力脊和平面内，即海冰相互之间的水平摩擦滑动所决定的。以前的实验研究和大多数建模工作都集中在垂直形变在确定冰应力中的作用，但使用特征跟踪算法得出的卫星观测表明，几乎所有的海冰变形都是由于面内摩擦滑动。这项拟议的研究将把人造海冰盖面内摩擦滑动的冰槽测量与数值模拟相结合，以给出一个经过验证的面内海冰变形模型和结果应力。导出的海冰应力模型将被纳入全球气候模式的海冰模型组成部分，并将其预测与北极海冰的运动、范围、密度和厚度的观测进行比较。新的海冰应力模型将提供给哈德利中心和其他气候模型小组。因此，拟议的研究方案在纯科学和技术建模方面都是及时的。

Satellite and submarine observations reveal the Arctic sea ice cover is thinning at a rapid rate. Recent computer modelling shows that predictions of sea ice export into the Greenland Sea, where it will melt to form a buoyant layer weakening downwelling and hence reducing the strength of the northern extent of the Gulf Stream, are highly sensitive to the treatment of forces in the sea ice cover. The model representation of sea ice forces is uncertain, but the stresses are principally determined by sea ice floes (which are 100 m to 10 km wide and a few metres thick) overiding each other in vertical deformation to form pressure ridges and by in-plane, i.e. horizontal, frictional sliding of sea ice floes past each other. Previous experimental studies and most modelling work has focussed on the role of vertical deformation in determining ice stresses but satellite observations, derived using algorithms for feature tracking, show that almost all the deformation of sea ice is due to in-plane frictional sliding. The proposed research will combine ice tank measurements of the in-plane frictional sliding of an artificial sea ice cover with numerical simulations to give a validated model of in-plane sea ice deformation and the stresses that result. The derived model of sea ice stress will be incorporated into the sea ice model component of an Global Climate Model and its predictions compared with observations of Arctic sea ice motion, extent, concentration, and thickness. The new sea ice stress model will be made available to the Hadley Centre and other climate modelling groups. The proposed programme of research is therefore timely in both its purely scientific and technical modelling aspects.