‘Surface Drag in the Arctic Marginal Sea-ice Zone: A Comparison of Different Parameterisation Concepts’
‘Surface Drag in the Arctic Marginal Sea-ice Zone: A Comparison of Different Parameterisation Concepts’
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DOI：
10.1007/s10546-005-1445-8
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发表时间：
2005-11
影响因子：
4.3
通讯作者：
C. Lüpkes;G. Birnbaum
中科院分区：
文献类型：
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作者：
C. Lüpkes;G. Birnbaum
进一步提出了两种北极边缘海冰区表面湍流通量和阻力系数的参数化方案，并对其结果进行了比较。虽然这些方案基于不同的原理（通量平均和参数平均），但在中性和稳定分层的情况下，所得阻力系数仅略有不同。对于不稳定分层和海峡东北部典型的海冰条件，采用参数平均方法得到的阻力系数比采用通量平均方法得到的阻力系数大5-10%。在海冰浓度为45%时，参数平均法将热通量高估了1.2倍。在由浮冰边缘和浮脊引起的形式阻力方案中加入对阻力系数和动量通量的影响要比在参数平均或通量平均方法之间的选择大得多。基于通量平均格式的敏感性研究，导出了北极MIZ上空有效阻力系数的简单公式。它减少了更复杂参数化的计算成本，也可以用于更大规模的模型。利用这个简单的公式，有效阻力系数可以计算为海冰浓度和水和浮冰表面阻力系数的函数。用这种参数化方法得到的结果与使用更复杂的方案得到的结果只有轻微的差别。最后，研究表明，在MIZ中，海冰模型的阻力系数可能与大气模型中使用的有效阻力系数存在显著差异。
Two parameterisation schemes for the turbulent surface fluxes and drag coefficients over the Arctic marginal sea-ice zone (MIZ) are (further) developed, and their results are compared with each other. Although the schemes are based on different principles (flux averaging and parameter averaging), the resulting drag coefficients differ only slightly in the case of neutral and stable stratification. For unstable stratification and sea-ice conditions being typical for the north-eastern Fram Strait, the drag coefficients resulting from the parameter-averaging concept are 5–10% larger than those of the flux-averaging concept. At a sea-ice concentration of 45%, the parameter-averaging method overestimates the heat fluxes by a factor of 1.2. An inclusion in the schemes of form drag caused by floe edges and ridges has a much larger effect on the drag coefficient, and on the momentum fluxes, than the choice between the parameter-averaging or flux-averaging methods. Based on sensitivity studies with the flux-averaging scheme, a simple formula for the effective drag coefficient above the Arctic MIZ is derived. It reduces the computational costs of the more complex parameterisations and could also be used in larger scale models. With this simple formula, the effective drag coefficient can be calculated as a function of the sea-ice concentration and skin drag coefficients for water and ice floes. The results obtained with this parameterisation differ only slightly from those using the more complex schemes. Finally, it is shown that in the MIZ, drag coefficients for sea-ice models may differ significantly from the effective drag coefficients used in atmospheric models.