Satellite-retrieved sea ice concentration uncertainty and its effect on modelling wave evolution in marginal ice zones
Satellite-retrieved sea ice concentration uncertainty and its effect on modelling wave evolution in marginal ice zones
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DOI：
10.5194/tc-14-2029-2020
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发表时间：
2020-06
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影响因子：
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通讯作者：
T. Nose;T. Waseda;T. Kodaira;J. Inoue
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文献类型：
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作者：
T. Nose;T. Waseda;T. Kodaira;J. Inoue
抽象的。众所周知，海洋表面波浪在与海冰相互作用时会衰减。在光谱波模型中实现的波冰模型，例如WAVEWATCH III® (WW3)，根据几种不同的模型冰类型得出衰减系数，即模型如何处理海冰。在海冰浓度 (SIC) < 1 的边缘冰区 (MIZ) 中，波浪衰减受到 SIC 的调节：我们表明，波冰模型中与 SIC 和海冰类型异质性相关的亚网格尺度过程缺失，而 SIC 的准确性在可预测性中起着重要作用。卫星检索的 SIC 数据（或同化它们的海冰模型）通常用于强制波冰模型，但已知这些数据具有不确定性。为了研究在重新结冰的楚科奇海进行 2018 年 R/V Mirai 观测活动期间 SIC 不确定性 ΔSIC 对 MIZ 波建模的影响，使用六颗卫星检索的 SIC 产品进行了 WW3 后报实验，该实验基于应用于 SSMIS 和 AMSR2 数据的四种算法。结果表明，ΔSIC 会导致冰盖中的波浪预测存在相当大的差异。有证据表明，双变量不确定性数据（模型有效波高和 SIC 强迫）是相关的，尽管由于 ΔSIC 沿 MIZ 提取的累积效应，冰外波的增长更加复杂。分析表明，ΔSIC 的影响可以克服因选择模型冰类型（即波冰相互作用参数化）而产生的不确定性。尽管在 WW3 波冰模型中缺少与 SIC 和海冰类型异质性相关的亚网格尺度物理，这导致了显着的建模不确定性，但这项研究发现，用作模型强迫的卫星检索的 SIC 的准确性是再冻结海洋中 MIZ 波建模的主要误差源。
Abstract. Ocean surface waves are known to decay when they interact with sea ice. Wave–ice models implemented in a spectral wave model, e.g. WAVEWATCH III® (WW3), derive the attenuation coefficient based on several different model ice types, i.e. how the model treats sea ice. In the marginal ice zone (MIZ) with sea ice concentration (SIC) < 1, the wave attenuation is moderated by SIC: we show that subgrid-scale processes relating to the SIC and sea ice type heterogeneity in the wave–ice models are missing and the accuracy of SIC plays an important role in the predictability. Satellite-retrieved SIC data (or a sea ice model that assimilates them) are often used to force wave–ice models, but these data are known to have uncertainty. To study the effect of SIC uncertainty ΔSIC on modelling MIZ waves during the 2018 R/V Mirai observational campaign in the refreezing Chukchi Sea, a WW3 hindcast experiment was conducted using six satellite-retrieved SIC products based on four algorithms applied to SSMIS and AMSR2 data. The results show that ΔSIC can cause considerable wave prediction discrepancies in ice cover. There is evidence that bivariate uncertainty data (model significant wave heights and SIC forcing) are correlated, although off-ice wave growth is more complicated due to the cumulative effect of ΔSIC along an MIZ fetch. The analysis revealed that the effect of ΔSIC can overwhelm the uncertainty arising from the choice of model ice types, i.e. wave–ice interaction parameterisations. Despite the missing subgrid-scale physics relating to the SIC and sea ice type heterogeneity in WW3 wave–ice models – which causes significant modelling uncertainty – this study found that the accuracy of satellite-retrieved SIC used as model forcing is the dominant error source of modelling MIZ waves in the refreezing ocean.