North Atlantic Current and European Slope Current Circulation in the Rockall Trough Observed Using Moorings and Gliders
North Atlantic Current and European Slope Current Circulation in the Rockall Trough Observed Using Moorings and Gliders
复制标题
DOI：
10.1029/2022jc019291
复制
发表时间：
2022-12-01
影响因子：
3.6
通讯作者：
Holliday, N. Penny
中科院分区：
文献类型：
--
作者：
Fraser, Neil J.;Cunningham, Stuart A.;Holliday, N. Penny
罗卡尔海槽（RT）容纳了北大西洋洋流最温暖和最咸的分支，它将墨西哥湾流的水输送到西欧周围的海洋环境。此外，欧洲斜坡流（ESC）携带温暖的水向北沿着东部边界的RT，和交流之间的ESC和大陆架是一个主导因素，在确定周围的不列颠群岛的海洋条件。然而，RT的平均环流和变率的图像仍在出现，持续的观测活动仍处于相对初期阶段。特别是ESC，船基，系泊和卫星观测的限制很差。在本文中，我们研究RT循环和体积运输使用时间上扩展和空间上扩展的观测网络。连续六年的系泊占用表明，之前在2015年左右在冰岛南部检测到的大幅度，盆地规模的清新事件在2017年左右影响了RT。在此期间，地转运输大大减少，在西部边界的并发次表层温度升高的驱动。在有记录以来的后期，环流恢复了强度。我们在22个月内收集了110个滑翔机断面，这些断面以前所未有的细节捕捉了ESC速度场。这些数据足以描述ESC的平均状态和紧急季节变化，并揭示了全年存在的向南逆流的深度。这种以前未研究过的功能的强度和结构的变化调制净向北运输的东部边界电流system.Plain语言摘要罗卡尔槽（RT）是一个关键的途径，温暖和咸水向北流动，一个过程中起着关键作用，决定了西欧的气候。然而，向北流动的水量及其随时间的变化仍然相当不确定。特别是，RT东部的窄边界电流以前已证明难以测量。在本文中，我们使用6年的连续海洋观测在RT监测流。我们还使用水下机器人，称为滑翔机，专注于东部边界的狭窄水流。收集的数据提供了迄今为止该区域洋流的最佳描述。研究期间恰逢北大西洋副极地发生深刻变化的时期，2017年左右在RT中检测到强烈的淡水信号。滑翔机的观测提供了狭窄的东部边界电流及其季节性变化的详细视图，并揭示了在深处存在向南流动的电流。
The Rockall Trough (RT) accommodates the warmest and saltiest branch of the North Atlantic Current, which delivers water from the Gulf Stream into the marine environment around western Europe. In addition, the European Slope Current (ESC) carries warm water northward along the eastern boundary of the RT, and exchange between the ESC and the continental shelf is a dominant factor in determining the oceanographic conditions around the British Isles. However, the picture of the mean circulation and variability in the RT is still emerging, with a continuous observational campaign still in its relative infancy. The ESC, in particular, is poorly constrained by ship-based, mooring, and satellite observations. In this paper, we examine the RT circulation and volume transport using a temporally extended and spatially expanded observing network. Six years of continuous mooring occupation reveal that a large-amplitude, basin-scale freshening event, previously detected south of Iceland around 2015, impacted the RT around 2017. Geostrophic transport was greatly reduced during this period, driven by a concurrent subsurface temperature increase at the western boundary. The circulation regained strength during the latter part of the record. We gathered 110 glider transects over 22 months which capture the ESC velocity field in unprecedented detail. The data are sufficient to characterize both the mean state and the emergent seasonal variability of the ESC, and reveal the year-round presence of a southward countercurrent at depth. Variability in the strength and structure of this previously unstudied feature modulates net northward transport in the eastern boundary current system.Plain Language Summary The Rockall Trough (RT) is a key pathway for warm and salty water flowing northward, a process which plays a key role in dictating the western European climate. However, the amount of water flowing northward, and how it changes over time, is still rather uncertain. In particular, the narrow boundary current in the eastern RT has previously proven difficult to measure. In this paper, we use 6 years of continuous oceanographic observations in the RT to monitor the flow. We also used underwater robots, called gliders, to focus on the narrow current in the eastern boundary. The data gathered give the best description of the ocean currents in the region to date. The study period coincided with a period of profound change across the subpolar North Atlantic, with a strong freshwater signal detected in the RT around 2017. The glider observations give a detailed view of the narrow eastern boundary current and how it varies seasonally, and also revealed the presence of a southward-flowing current at depth.