Impact of a new anisotropic rheology on simulations of Arctic sea ice
Impact of a new anisotropic rheology on simulations of Arctic sea ice
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DOI：
10.1029/2012jc007990
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发表时间：
2013-01-01
影响因子：
3.6
通讯作者：
Wilchinsky, A. V.
中科院分区：
文献类型：
--
作者：
Tsamados, M.;Feltham, D. L.;Wilchinsky, A. V.
一个新的流变学，明确占海冰覆盖的亚连续各向异性实施到洛斯阿拉莫斯海冰模型。这与全球环流模型中使用各向同性流变学的所有海冰模型相反。该模型包含一个新的预测变量，局部结构张量，它量化的海冰的各向异性程度，和两个参数，设置这个张量的演变的时间尺度。各向异性流变学提供了海冰力学行为的亚连续描述，并解释了具有大剪压比和张应力分量的连续尺度应力。结果在北极的一个独立的版本的模型和各向异性模型的灵敏度运行进行了比较与参考弹粘塑性模拟。在现实的强迫下，海冰在大的长度尺度上迅速变得高度各向异性，正如卫星图像所观察到的那样。新的流变学的海冰覆盖的状态和动力学的影响进行了讨论。我们的参考各向异性运行表明，新的流变学导致冰厚度和冰漂移的空间分布相对于参考标准粘塑性各向同性运行的实质性变化，冰厚度区域增加超过1米，冰速度降低高达50%。
A new rheology that explicitly accounts for the subcontinuum anisotropy of the sea ice cover is implemented into the Los Alamos sea ice model. This is in contrast to all models of sea ice included in global circulation models that use an isotropic rheology. The model contains one new prognostic variable, the local structure tensor, which quantifies the degree of anisotropy of the sea ice, and two parameters that set the time scale of the evolution of this tensor. The anisotropic rheology provides a subcontinuum description of the mechanical behavior of sea ice and accounts for a continuum scale stress with large shear to compression ratio and tensile stress component. Results over the Arctic of a stand-alone version of the model are presented and anisotropic model sensitivity runs are compared with a reference elasto-visco-plastic simulation. Under realistic forcing sea ice quickly becomes highly anisotropic over large length scales, as is observed from satellite imagery. The influence of the new rheology on the state and dynamics of the sea ice cover is discussed. Our reference anisotropic run reveals that the new rheology leads to a substantial change of the spatial distribution of ice thickness and ice drift relative to the reference standard visco-plastic isotropic run, with ice thickness regionally increased by more than 1 m, and ice speed reduced by up to 50%.