A comparison of five surface mixed layer models with a year of observations in the North Atlantic
A comparison of five surface mixed layer models with a year of observations in the North Atlantic
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DOI：
10.1016/j.pocean.2020.102316
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发表时间：
2020-08-01
影响因子：
4.1
通讯作者：
Belcher, Stephen E.
中科院分区：
文献类型：
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作者：
Damerell, Gillian M.;Heywood, Karen J.;Belcher, Stephen E.
将由 ERA-Interim 表面强迫驱动的五个上层海洋混合层模型与使用剖面滑翔机在豪猪深渊平原观测站进行的上层 1000 米一年的水文观测进行了比较。所有模型都很好地再现了海面温度 (SST)，年平均暖偏差为 0.11 摄氏度（PWP 模型）、0.24 摄氏度（GLS）、0.31 摄氏度（TKE）、0.91 摄氏度（KPP）和 0.36 摄氏度（OSMOSIS）。主要的例外是 KPP 模型的夏季海温比观测值高近 3 度。混合层盐度 (MLS) 模型不能很好地再现，并且偏差足够大，足以在冬季在该地区形成的东北大西洋中央水域中产生非平凡的密度偏差。所有模型都在冬季形成太深的混合层，平均冬季混合层深度 (MLD) 偏差在 160 至 228 m 之间。与基于水柱特性的 MLD 模型相比，通过主动混合深度和/或边界层深度的模型估计可以更成功地再现冬季 MLD 的高变异性。春季重层化事件之后，MLD的偏差很小，似乎与之前的冬季偏差无关。在所有模型以及春季和夏季的观测中，MLD和局地风应力之间都存在非常明显的关系，风速增加导致混合层加深，但这种关系在秋季和冬季不存在。我们假设秋季 MLD 的加深是由地表热通量年度循环强烈驱动的，因此秋季的风不太明显。从三月份开始，地表热通量驱动 MLD 和 SST 的昼夜循环，尽管这种影响在模型中比在观测中更为显着。我们无法确定一个模型绝对优于其他模型。这些模型之间唯一明显的区别是 KPP 无法准确再现夏季海表温度，而 OSMOSIS 模型可以更准确地再现 MLS。
Five upper ocean mixed layer models driven by ERA-Interim surface forcing are compared with a year of hydrographic observations of the upper 1000 m, taken at the Porcupine Abyssal Plain observatory site using profiling gliders. All the models reproduce sea surface temperature (SST) fairly well, with annual mean warm biases of 0.11 degrees C (PWP model), 0.24 degrees C (GLS), 0.31 degrees C (TKE), 0.91 degrees C (KPP) and 0.36 degrees C (OSMOSIS). The main exception is that the KPP model has summer SSTs which are higher than the observations by nearly 3 degrees. Mixed layer salinity (MLS) is not reproduced well by the models and the biases are large enough to produce a nontrivial density bias in the Eastern North Atlantic Central Water which forms in this region in winter.All the models develop mixed layers which are too deep in winter, with average winter mixed layer depth (MLD) biases between 160 and 228 m. The high variability in winter MLD is reproduced more successfully by model estimates of the depth of active mixing and/or boundary layer depth than by model MLD based on water column properties. After the spring restratification event, biases in MLD are small and do not appear to be related to the preceding winter biases.There is a very clear relationship between MLD and local wind stress in all models and in the observations during spring and summer, with increased wind speeds leading to deepening mixed layers, but this relationship is not present during autumn and winter. We hypothesize that the deepening of the MLD in autumn is so strongly driven by the annual cycle in surface heat flux that the winds are less significant in the autumn. The surface heat flux drives a diurnal cycle in MLD and SST from March onwards, though this effect is much more significant in the models than in the observations.We are unable to identify one model as definitely better than the others. The only clear differences between the models are KPP's inability to accurately reproduce summer SSTs, and the OSMOSIS model's more accurate reproduction of MLS.