An elastic plate model for wave attenuation and ice floe breaking in the marginal ice zone
An elastic plate model for wave attenuation and ice floe breaking in the marginal ice zone
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DOI：
10.1029/2007jc004434
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发表时间：
2008-09-09
影响因子：
3.6
通讯作者：
Meylan, M. H.
中科院分区：
文献类型：
--
作者：
Kohout, A. L.;Meylan, M. H.
本文提出了一种基于二维（一个水平和一个垂直维度）多重浮动弹性板频域解的边缘冰带（MIZ）波衰减模型，该模型使用匹配的特征函数展开进行精确求解。进入模型的唯一物理参数是浮冰的长度、质量和弹性刚度（其中后两者主要取决于厚度）。该模型忽略了所有非线性效应以及浮冰碰撞或冰蠕变，因此最适用于比厚度大的浮冰和非极端的波浪条件。对于给定的絮体排列的解是完全一致的，因此结果依赖于精确的几何形状。我们首先表明，这种依赖性可以通过对流长度分布（我们选择瑞利分布）进行平均来消除。然后，我们表明，在此平均之后，衰减系数是一个独立于流长度的函数，只要流长度足够大。该模型预测能量呈指数衰减，正如实验所显示的那样。这使我们能够提供衰减系数的显式值，作为平均流厚度和波周期的函数。我们将波衰减的理论预测与实测数据和其他散射模型进行了比较。有限的数据使我们得出结论，我们的模型适用于短至中波周期（6至15秒）的大浮冰。在波浪衰减模型的基础上，我们还推导出了一个浮冰破碎模型，这表明我们对长周期衰减系数的预测不足。
We present a model for wave attenuation in the marginal ice zone (MIZ) based on a two-dimensional (one horizontal and one vertical dimension) multiple floating elastic plate solution in the frequency domain, which is solved exactly using a matched eigenfunction expansion. The only physical parameters that enter the model are length, mass, and elastic stiffness (of which, the latter two depend primarily on thickness) of the ice floes. The model neglects all nonlinear effects as well as floe collisions or ice creep and is therefore most applicable to floes which are large compared to the thickness and to wave conditions which are not extreme. The solution for a given arrangement of floes is fully coherent, and the results are therefore dependent on the exact geometry. We firstly show that this dependence can be removed by averaging over a distribution of floe lengths (we choose the Rayleigh distribution). We then show that after this averaging, the attenuation coefficient is a function of floe number and independent of floe length, provided the floe lengths are sufficiently large. The model predicts an exponential decay of energy, just as is shown experimentally. This enables us to provide explicit values for the attenuation coefficient, as a function of the average floe thickness and wave period. We compare our theoretical predictions of the wave attenuation with measured data and other scattering models. The limited data allows us to conclude that our model is applicable to large floes for short to medium wave periods (6 to 15 seconds). We also derive a floe breaking model, based on our wave attenuation model, which indicates that we are under-predicting the attenuation coefficients at long periods.