A description and analysis of mesoscale variability in the Färoe‐Shetland Channel
A description and analysis of mesoscale variability in the Färoe‐Shetland Channel
复制标题
法罗-设得兰海峡中尺度变化的描述和分析
DOI：
10.1029/2005jc002867
复制
发表时间：
2006
影响因子：
--
通讯作者：
P. I. Miller
中科院分区：
文献类型：
--
作者：
T. Sherwin;Martin Williams;W. Turrell;S. Hughes;P. I. Miller
[1] 流入北欧海的大部分地表水流在法罗-设得兰海峡汇合成窄坡流，并沿着设得兰陆架边缘以平均速度 0.4 m/s 的速度流动。观测表明，水流不稳定，在沿河道的两个水团之间的前沿形成大的中尺度曲流，流速高达 0.9 m/s。曲流往往在两个特定位置形成。对漂流器和高度计档案数据的长期分析表明，热点涡流动能大于 300 cm2/s，表面高程变化接近 40 cm2。斜压不稳定性分析表明，曲流的生长时间应该是几天，分离距离约为 65 km，并且根据 500 m 以下向南流出的强度，它们的群速度可能非常接近于零。因此，与挪威海岸流中的对应物不同，不稳定因素不会传播。反气旋曲流的衰退可能导致气旋涡流的形成，气旋涡流将北大西洋水和改良北大西洋水（MNAW）混合在一起，并形成更均匀的大西洋水形式，当水向北移动穿过海峡并进入挪威海时，可以观察到这种形式。中尺度驱动的夹带可能有助于将 MNAW 从法罗群岛周围吸引到法罗-设得兰海峡。
[1] A large part of the surface inflow to the Nordic Seas coalesces into a narrow slope current in the Faroe-Shetland Channel, and flows along the Shetland shelf edge with mean speeds of order 0.4 m/s. Observations reveal that the flow is unstable and forms large mesoscale meanders with current speeds of up to 0.9 m/s in a front between two water masses that lies along the channel. The meanders tend to form at two specific locations. Long-term analyses of drifter and altimeter archive data show hot spots in eddy kinetic energy that are greater than 300 cm2/s, and in surface elevation variance that are nearly 40 cm2. A baroclinic instability analysis suggests that the growth time of the meanders should be a few days, with a separation distance of order 65 km, and that their group velocity could be very close to zero depending on the strength of the southward outflow below 500 m. Thus, unlike their counterparts in the Norwegian Coastal Current, for example, the instabilities do not propagate. Decay of the anticyclonic meanders probably leads to the formation of cyclonic eddies that mix North Atlantic Water and Modified North Atlantic Water (MNAW) and create the more homogeneous forms of Atlantic water that are observed as the water moves northward through the channel and into the Norwegian Sea. Mesoscale driven entrainment may help to draw MNAW into the Faroe-Shetland Channel from around Faroe.