Modeling of the Influence of Sea Ice Cycle and Langmuir Circulation on the Upper Ocean Mixed Layer Depth and Freshwater Distribution at the West Antarctic Peninsula
Modeling of the Influence of Sea Ice Cycle and Langmuir Circulation on the Upper Ocean Mixed Layer Depth and Freshwater Distribution at the West Antarctic Peninsula
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DOI：
10.1002/essoar.10502066.1
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发表时间：
2020-01
期刊：
影响因子：
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通讯作者：
Cristina Schultz;S. Doney;W. Zhang;H. Regan;P. Holland;Michael P. Meredith;S. Stammerjohn
中科院分区：
文献类型：
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作者：
Cristina Schultz;S. Doney;W. Zhang;H. Regan;P. Holland;Michael P. Meredith;S. Stammerjohn
南大洋由于其偏远、恶劣的环境和海冰覆盖而长期采样不足。海洋环流模型对关键过程有重要的洞察力，并在一定程度上弥补了数据的缺乏;然而，它们往往低估了表面混合层深度（MLD），对表面水柱温度，盐度和营养盐浓度产生影响。在这项研究中，一个耦合的环流和海冰模式实现了邻近地区的西南极半岛，气候敏感的地区，表现出十年的趋势，海洋温度升高，海冰季节缩短，并增加冰川淡水输入，叠加强烈的年际变化。使用不同的空气-冰阻力系数和朗缪尔环流参数化进行了后播模拟，以确定这些因素对MLD的影响。包括朗缪尔环流加深了表面混合层，加深在陆架和斜坡地区更为明显。空气-冰阻力系数的最佳选择也使模拟的MLD增加了类似的数量，并对提高模拟MLD年际变化的可靠性产生了更大的影响。这项研究强调了海冰体积和重新分布的重要性，以正确地再现底层海洋的物理特性，以及适当参数化朗缪尔环流的潜力，以帮助纠正对南大洋浅层MLD的偏见。该模型还再现肯珀进行了测试，这些参数化的每一个开发的开放的海洋和全球模式中实施。海冰和海岸线在我们的区域模型的额外的挑战，考虑到不确定性相关的行为，在海冰的存在下，在沿海地区的海浪和表面波，以及不同的属性。Li和Fox-Kemper（2017）描述的方法参数化了LC在混合层下方夹带稠密水时的影响。由于卷吸作用，卷吸冰拖曳系数导致季节和年际海冰变率的代表性存在很大差异。CTRL模拟具有较高的阻力系数（2 × 10 − 3），与观测结果相比，显示出更高的SIC和后期海冰退缩的倾向。这些偏差在低阻力系数（5 × 10 − 4）的模拟中被放大了艾德。在海冰后退期间，不同阻力系数的模拟之间的差异要比海冰前进期间大得多，这表明后退更受风作用的影响。海冰期间模式之间SIC的较小差异表明模式所用的海洋温度和盐度初始条件存在偏差。
The Southern Ocean is chronically undersampled due to its remoteness, harsh environment, and sea ice cover. Ocean circulation models yield signi fi cant insight into key processes and to some extent obviate the dearth of data; however, they often underestimate surface mixed layer depth (MLD), with consequences for surface water ‐ column temperature, salinity, and nutrient concentration. In this study, a coupled circulation and sea ice model was implemented for the region adjacent to the West Antarctic Peninsula, a climatically sensitive region which has exhibited decadal trends towards higher ocean temperature, shorter sea ice season, and increasing glacial freshwater input, overlain by strong interannual variability. Hindcast simulations were conducted with different air ‐ ice drag coef fi cients and Langmuir circulation parameterizations to determine the impact of these factors on MLD. Including Langmuir circulation deepened the surface mixed layer, with the deepening being more pronounced in the shelf and slope regions. Optimal selection of an air ‐ ice drag coef fi cient also increased modeled MLD by similar amounts and had a larger impact in improving the reliability of the simulated MLD interannual variability. This study highlights the importance of sea ice volume and redistribution to correctly reproduce the physics of the underlying ocean, and the potential of appropriately parameterizing Langmuir circulation to help correct for biases towards shallow MLD in the Southern Ocean. The model also reproduces Kemper are tested Each of these parameterizations was developed for open ocean and implemented in global models. The of sea ice and a coastline in our regional model an additional challenge given the uncertainties related to the behavior of wind and surface waves in the presence of sea ice, and the different properties of waves in coastal areas. The approach described by Li and Fox ‐ Kemper (2017) parameterizes the in fl uence of LC in the entrainment of dense water from below the mixed layer. of entrainment, entrainment ice drag coef fi cient leads to large differences in the representation of seasonal and interannual sea ice variability. The CTRL simulation, which has a higher drag coef fi cient (2 × 10 − 3 ), shows a bias towards higher SIC and late sea ice retreat when compared to the observations. These biases are ampli fi ed in the simulation with low (5 × 10 − 4 ) drag coef fi cient. The difference between simulations with different drag coef fi cients is much larger during the period of sea ice retreat than during sea ice advance, suggesting that retreat is more in fl uenced by wind action. The smaller differences in SIC between models during sea ice that there are biases in the initial conditions of ocean temperature and salinity used for the model.