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Deep drivers of mesoscale circulation in the central Rockall Trough

机译：Rockall槽中央中尺度环流的深层驱动力

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Mesoscale variability in the central Rockall Trough between about 56 and 58° N has been investigated using a combination of ship-borne, underwater glider and gridded satellite altimeter measurements. Altimeter observations show that mesoscale features such as eddies and large scale circulation cells are ubiquitous phenomena. They have horizontal length scales of order 100 km with vertical scales of over 1000 m and are associated with mean current speeds (over the upper 1000 m) of 15 ± 7 cm s?1. Monthly area averaged surface Eddy Kinetic Energy (EKE) has substantial inter-annual variability, which at times can dominate a mean seasonal signal that varies from a maximum in May (74 cm2 s?2) to a minimum in October (52 cm2 s?2) and has increased gradually since 1992 at about 1.1 cm2 s?2 per year. A five month glider mission in the Trough showed that much of this energy comes from features that are located over 1000 m below the surface in the deep cold waters of the Trough (possibly from eddies associated the North Atlantic Current). The surface currents from altimeters had similar magnitude to the drift currents averaged over 1000 m from the glider in the stratified autumn, but were half the deep water speed during late winter. Although the mesoscale features move in an apparent random manner they may also be quasi-trapped by submarine topography such as seamounts. Occasionally anti-cyclonic and cyclonic cells combine to cause a coherent westward deflection of the European slope current that warms the Rockall side of the Trough. Such deflections contribute to the inter-annual variability in the observed temperature and salinity that are monitored in the upper 800 m of the Trough. By combining glider and altimeter measurements it is shown that altimeter measurements fail to observe a 15 cm s?1 northward flowing slope current on the eastern side and a small persistent southward current on the western side. There is much to be gained from the synergy between satellite altimetry and in situ glider observations both in the interpretation of their separate data sets and in aiding glider pilots to steer their vehicles through EKE active regions such as the north-east Atlantic.
机译：结合使用舰载，水下滑翔机和网格化卫星高度计的测量，已经研究了洛克中心低谷在56至58°N之间的中尺度变化。高度计的观测结果表明，涡流和大规模循环池等中尺度特征是普遍存在的现象。它们的水平长度尺度为100 km，垂直尺度超过1000 m，并与15±7 cm s s ？1 的平均当前速度（超过1000 m）有关。月面积平均表面涡流动能（EKE）具有较大的年际变化，有时可支配5月的最大值（74 cm 2 s ？2 ）到十月份的最小值（52 cm 2 s ？2 ），并且自1992年以来逐渐增加，约为1.1 cm 2 每年s ？2 。在低谷中进行的为期五个月的滑行飞行任务表明，这些能量中的大部分来自位于深槽深处海表以下1000 m以上的特征（可能来自与北大西洋洋流有关的涡流）。高度计的地表电流与分层秋天秋季滑翔机平均流过1000 m时的漂移电流大小相似，但在深夜时仅为深水速度的一半。尽管中尺度特征以明显的随机方式移动，但它们也可能被海底地形等海底地形所困。有时，反气旋和气旋细胞结合在一起，引起欧洲斜坡电流的连贯向西偏转，从而温暖了海槽Rockall一侧。这种偏转会导致观测到的温度和盐度的年际变化，并在槽的上部800 m进行监测。结合滑翔机和高度计测量结果，可以看出，高度计测量未能观测到东侧的15 cm s ？1 北向流动的斜流和西侧的持续小南向流。卫星测高和原地滑翔机观测之间的协同增效，不仅可以解释各自的数据集，还可以帮助滑翔机飞行员驾驶车辆穿越EKE活动区域，例如东北大西洋。

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