On the Northwest European Shelf rivers provide freshwater to the coastal seas. This coastal freshwater can be misrepresented in ocean models without effective coastal resolution. This leaves an unanswered question; is freshwater retained around Scotland and what affects its variability? Here, we deploy and run an unstructured model with enhanced coastal resolution to simulate the Northwest European Shelf from 1993 to 2019, the Scottish Shelf Water-Reanalysis Service (SSW-RS) long-time run. The unstructured nature of the model grid means it more accurately captures a “bubble” of Coastal Water than a 7 km structured grid model (the Atlantic Margin Model 7 km). Surface salinity in the SSW-RS shows salinity fronts within 80 km of the coast around west and north Scotland that disintegrates east of Orkney. There are periods characterized by high coastal salinity when freshwater is more actively advected away from the coast. Empirical orthogonal function statistical analysis shows the first two modes in surface salinity account for 66% of the variance. The first mode correlates with North Atlantic Oscillation and the salinity driven velocity variability which change the salinity through advection and diffusion. The second mode correlates with Ekman transport variability where the north of Scotland acts as a wedge causing bipolar dynamics either side. Freshwater is trapped in the west, while saline water from the north reduces the freshwater pathway to the North Sea. This is important for salinity distribution, stratification in the North Sea, marine habitats and frontal transport.

中文翻译：

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相干沿海淡水影响系统的形成和动力学

在欧洲西北部大陆架，河流为沿海海域提供淡水。如果没有有效的沿海分辨率，这些沿海淡水可能会在海洋模型中被歪曲。这留下了一个悬而未决的问题；苏格兰周围是否保留了淡水？是什么影响了其变化？在这里，我们部署并运行了一个具有增强海岸分辨率的非结构化模型，以模拟 1993 年至 2019 年的西北欧洲大陆架，即苏格兰陆架水再分析服务 (SSW-RS) 的长期运行。模型网格的非结构化性质意味着它比 7 公里结构化网格模型（大西洋边缘模型 7 公里）更准确地捕获沿海水域的“气泡”。SSW-RS 的表面盐度显示，苏格兰西部和北部周围海岸 80 公里范围内的盐度锋面在奥克尼群岛东部解体。在某些时期，沿海盐度较高，淡水会更加活跃地平流离开海岸。经验正交函数统计分析表明，表面盐度的前两种模式占方差的 66%。第一种模式与北大西洋涛动和盐度驱动的速度变化相关，后者通过平流和扩散改变盐度。第二种模式与埃克曼输运变异性相关，其中苏格兰北部充当楔子，导致双方两极动态。淡水被困在西部，而来自北部的咸水则减少了通往北海的淡水通道。这对于北海的盐度分布、分层、海洋栖息地和锋面输送非常重要。