Gulf Stream flow field and events near 68°W
Gulf Stream flow field and events near 68°W
复制标题
墨西哥湾流流场和 68°W 附近的事件
DOI：
10.1029/95jc02685
复制
发表时间：
1995
影响因子：
--
通讯作者：
K. Tracey
中科院分区：
文献类型：
--
作者：
T. J. Shay;J. Bane;D. Watts;K. Tracey
SYNoptic Ocean Prediction（SYNOP）实验旨在准确了解墨西哥湾流中的高能中尺度过程。中央阵列测量了整个水柱的速度和温度，水平范围大到几乎足以跨越68°W处急流的曲流包络和欧拉平均结构。55至70公里的系泊间距解决了中尺度涡与墨西哥湾流的相互作用，26个月的持续时间允许稳定的长期平均场的估计。六个陡峭的曲流槽传播或在阵列内发展，每个持续约30-60天，因此在急流高度（1000米及以上）的主要向东气流中在68°W附近留下了一个小的平均槽。在深层次（3500米）的平均流量是西南方向的岸边网站浅于4300米，但它流动的气旋周围的平均低压异常影响所有较深的离岸网站。每单位质量的涡动动能（E K）减少了约2.5倍，从400至700至1000米的每一个深度增量，但只有一个因素，在3500米比在1000米小2。高空中心急流（400 m）的E-K值为100 ~ 230 mJ·kg-1，3500 m时为4-13 mJ·kg-1。总体而言，68°W处上部1000 m处的E K高于之前发布的55°W处的值。两个扩展的情况下，通过阵列的曲流传播的研究表明，墨西哥湾流下的深气旋和反气旋流的发展和加强。3500 m处的气旋流与放大的曲流槽有关，常超过0.35ms-1，远大于典型的0.05ms-1深平均流速。
The SYNoptic Ocean Prediction (SYNOP) experiment was designed to provide an accurate understanding of the energetic mesoscale processes in the Gulf Stream. The Central Array measured velocity and temperature throughout the water column, with horizontal extent large enough nearly to span the meander envelope and Eulerian mean structure of the jet at 68°W. The 55- to 70-km mooring spacing resolved mesoscale eddy interactions with the Gulf Stream, and the 26-month duration allowed stable estimation of long-term mean fields. Six steep meander troughs propagated into or developed within the array, each lasting around 30-60 days, thus impressing a small mean trough near 68°W in the predominantly eastward currents at jet level (1000 m and above). At the deep level (3500m) the mean flow was southwest at the shoreward sites shallower than 4300 m, but it flowed cyclonically around a mean low-pressure anomaly affecting all the deeper offshore sites. The eddy kinetic energy per unit mass (E K ) decreased by a factor of about 2.5 with each depth increment from 400 to 700 to 1000 m but was only a factor of 2 smaller at 3500 m than at 1000 m. Values of E K in the upper central jet (400 m) were 100 to 230 mJ kg -1 and were 4-13 mJ kg -1 at 3500 m. Overall, E K in the upper 1000m at 68°W was higher than previously published values at 55°W. Two extended case studies of meander propagation through the array demonstrate the development and intensification of deep cyclonic and anticyclonic flows beneath the Gulf Stream. The cyclonic flow at 3500m, associated with amplifying meander troughs, often exceeded 0.35 ms -1 , which was much larger than the typical 0.05 ms -1 deep mean velocities.