Variability of subtidal current structure in a fjord estuary: Puget Sound, Washington
Variability of subtidal current structure in a fjord estuary: Puget Sound, Washington
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峡湾河口潮下流结构的变化：华盛顿州普吉特湾
DOI：
10.1029/jc090ic06p11949
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发表时间：
1985
影响因子：
--
通讯作者：
D. Pashinski
中科院分区：
文献类型：
--
作者：
D. E. Bretschneider;G. A. Cannon;J. Holbrook;D. Pashinski
1983 年 3 月至 4 月期间，在 31 天的时间内对普吉特湾东航道的一段海流和水特性进行了同步观测。这些观测结果辅以 CTD 剖面、岸基风力数据和远场海流测量，用于描述潮下流的跨海峡变化。平均环流由近地表的向海流和7 m以下的向陆流组成，最大速度核心位于中深度。运输量为 22,000 m3/s。地形效应迫使大部分向海的补偿流通过邻近的航道，在中间的岛屿周围形成顺时针环流。采用经验正交函数分析来描述电流波动的空间结构。在潮下时间尺度上，三种环流模式是明显的：（1）近地表（上部20 m）风驱动切变； (2) 近底层（150-200 m），以密度流为主，密度流在普吉特湾入口处的小潮混合期间产生后向河口传播； （3）中间层（25-75 m），受科尔沃斯航道水部分回流的影响，并受到非线性混合潮汐的每两周一次的调制。目前的这些观测首次显示了从科尔沃斯航道向海流向东航道向陆流的再循环。
Simultaneous observations of currents and water properties were made in a section across East Passage in Puget Sound over a 31-day period between March and April 1983. These observations, supplemented with CTD profiles, shore-based wind data, and far-field current measurements, were used to describe the cross-channel variability of subtidal currents. The mean circulation consisted of seaward flow in the near surface and landward flow below 7 m, with a core of maximum velocity at mid-depth. Volume transport was 22,000 m3/s. Topographic effects force most of the seaward compensating flow through an adjacent channel, creating a clockwise circulation around an intervening island. Empirical orthogonal function analysis was used to describe the spatial structure of current fluctuations. At subtidal time scales, three circulation modes are evident: (1) a near-surface (upper 20 m), wind-driven shear; (2) a near-bottom layer (150–200 m) dominated by density currents that propagate up estuary after generation during neap tidal mixing at the entrance sill to Puget Sound; and (3) an intermediate layer (25–75 m) influenced by partial refluxing of Colvos Passage water and modulated at fortnightly periods by nonlinear mixed tides. These current observations are the first to show recirculation of seaward flowing water from Colvos Passage to landward flow in East Passage.