The Eastern Boundary Current is an essential part of the water mass exchange between the subtropical and subpolar North Atlantic. Here, we study the offshore branch of the European Shelf Current (ESC) over the Goban Spur slope area off Ireland. Our analysis is based on current measurements obtained from a multiyear mooring effort, complemented by ship-board observations along a hydrographic section, satellite-derived estimates of absolute dynamic topography with geostrophic currents, and float trajectories. These data serve to quantify the offshore branch of the ESC on intraannual to interannual timescales. From the moored observations, we derive a mean poleward along-slope volume flux of 3.7 0.7 Sv for the period 2017–2019. Using a multilinear regression model and geostrophic surface velocities, we extend the time series to the period 1993–2019 and obtain a long-term mean transport of 3.2 0.4 Sv. Both time series show strong variability ranging from −7.5 to 15.7 Sv. The variability is linked to a dynamic eddy field, especially a stationary cyclonic circulation pattern near the mooring array, and meandering of current branches originating from the North Atlantic Current.

中文翻译：

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Goban Spur 北大西洋东部边界流的体积输运时间序列和变异性

东部边界流是亚热带和次极北大西洋之间水体交换的重要组成部分。在这里，我们研究了欧洲大陆架洋流 (ESC) 的离岸分支，该分支位于爱尔兰外的戈班 Spur 斜坡区域。我们的分析基于从多年系泊工作中获得的当前测量值，辅以沿水文剖面的船上观测、卫星衍生的地转流绝对动态地形估计值和浮标轨迹。这些数据用于在年内到年际时间尺度上量化 ESC 的离岸分支。从系泊观测中，我们推导出平均向极沿坡体通量为 3.72017-2019 年期间为 0.7 Sv。使用多元线性回归模型和地转表面速度，我们将时间序列扩展到 1993-2019 年期间，并获得 3.2 0.4 Sv的长期平均传输。两个时间序列都显示出从 -7.5 到 15.7 Sv 的强烈可变性。这种变化与动态涡流场有关，尤其是系泊阵列附近的固定气旋环流模式，以及源自北大西洋洋流的电流分支的蜿蜒曲折。