Spatial scaling of Arctic sea ice deformation
Spatial scaling of Arctic sea ice deformation
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DOI：
10.1029/2009jc005380
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发表时间：
2009-10-21
影响因子：
3.6
通讯作者：
Lindsay, R. W.
中科院分区：
文献类型：
--
作者：
Stern, H. L.;Lindsay, R. W.
北极海冰变形是由冰速度场的空间梯度引起的。这种变形发生在很宽的空间尺度上，从几米到几千公里。我们分析了7年的海冰变形数据从雷达卫星地球物理处理器系统（RGPS）覆盖北冰洋西部。我们发现，在10 ~ 1000 km（e.例如，在一个实施例中，变形率翻倍，规模缩小30倍）。变形指数和变形速率都有明显的年周期。在夏季，随着冰层的减弱，内部应力不容易长距离传输，指数变得更负。变形速率在冬季最强时达到最小值。变形也表现出相当大的本地化，其中最大的变形率被限制在越来越小的区域作为测量规模的减小。这支持了基于颗粒或断裂力学的海冰模型。幂律关系中的标度指数在多年冰浓度低的地方往往较大，与较薄和较弱的冰层相一致。随着北极多年冰的减少和冰层的变薄，变形率的增加已经被记录在案（来自浮标数据）。然而，几个变形/厚度反馈的净效应仍然是不确定的。
Arctic sea ice deformation arises from spatial gradients in the ice velocity field. This deformation occurs across a wide range of spatial scales, from meters to thousands of kilometers. We analyze 7 years of sea ice deformation data from the RADARSAT Geophysical Processor System (RGPS) covering the western Arctic Ocean. We find that the mean deformation rate is related to the spatial scale over which it is measured according to a power law with exponent similar to-0.2, over a scale range from 10 to 1000 km (e. g., deformation rate doubles for a 30-fold reduction in scale). Both the exponent and the deformation rate have distinct annual cycles. The exponent becomes more negative in summer as the ice pack weakens and internal stresses are not as readily transmitted over long distances. The deformation rate reaches a minimum in late winter when the ice pack is strongest. The deformation also exhibits considerable localization, in which the largest deformation rates are confined to smaller and smaller areas as the scale of measurement decreases. This supports a model for sea ice based on granular or fracture mechanics. The scaling exponent in the power law relationship tends to be larger in magnitude where the concentration of multiyear ice is low, consistent with a thinner and weaker ice pack. With decreasing multiyear ice in the Arctic and a thinning ice pack, an increase in the deformation rate has already been documented (from buoy data). However, the net effect of several deformation/ thickness feedbacks is still uncertain.