Linkage between lateral circulation and near-surface vertical mixing in a coastal plain estuary
Linkage between lateral circulation and near-surface vertical mixing in a coastal plain estuary
复制标题
沿海平原河口侧向环流与近地表垂直混合之间的联系
DOI：
10.1002/2014jc010679
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发表时间：
2015
影响因子：
--
通讯作者：
A. Souza
中科院分区：
文献类型：
--
作者：
Kimberly D. Huguenard;A. Valle‐Levinson;Ming Li;R. Chant;A. Souza
为了研究跨河口垂直混合的变化，于2010年5月在大潮和小潮条件下采集了詹姆斯河跨海峡断面的微结构和流速测量数据。结果表明，在潮汐周期的落潮阶段，近地表混合与侧向环流有关，从小潮到大潮的联系有些相似。在小潮期间，由于断面右侧(朝海)的淡水平流影响横向密度梯度的应变，产生了近地表混合。大潮结果在横截面的右侧也有类似的发现。然而，在左侧，速度剪切的应变与密度应变是一致的。左浅滩上沿河口的微弱流速通过顺时针方向的横向环流(面向大海)与航道中较快的流速联系在一起。这些结果提供了证据，证明在没有直接风强迫的情况下，近地表垂直混合可以通过与底部摩擦不耦合的机制发生。
Microstructure and current velocity measurements were collected at a cross-channel transect in the James River under spring and neap tidal conditions in May 2010 to study cross-estuary variations in vertical mixing. Results showed that near-surface mixing was related to lateral circulation during the ebb phase of a tidal cycle, and that the linkage was somewhat similar from neap to spring tides. During neap tides, near-surface mixing was generated by the straining of lateral density gradients influenced by the advection of fresh, riverine water on the right side (looking seaward) of the transect. Spring tide results revealed similar findings on the right side of the cross section. However, on the left side, the straining by velocity shears acted in concert with density straining. Weak along-estuary velocities over the left shoal were connected to faster velocities in the channel via a clockwise lateral circulation (looking seaward). These results provided evidence that in the absence of direct wind forcing, near-surface vertical mixing can occur from mechanisms uncoupled from bottom friction.