Mixing of the Connecticut River Plume During Ambient Flood Tides: Spatial Heterogeneity and Contributions of Bottom‐Generated and Interfacial Mixing
Mixing of the Connecticut River Plume During Ambient Flood Tides: Spatial Heterogeneity and Contributions of Bottom‐Generated and Interfacial Mixing
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DOI：
10.1029/2023jc020423
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发表时间：
2024-03
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影响因子：
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通讯作者：
M. Whitney;P. Spicer;D. MacDonald;Kimberly D. Huguenard;K. Cole;Yan Jia;Nikiforos Delatolas
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文献类型：
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作者：
M. Whitney;P. Spicer;D. MacDonald;Kimberly D. Huguenard;K. Cole;Yan Jia;Nikiforos Delatolas
康涅狄格河羽流受到长岛海峡接收沃茨中充满活力的环境潮汐的影响。本模拟研究的目标是（a）表征湍流浮力通量的空间异质性，（B）将湍流浮力通量划分为底部生成和界面剪切贡献，以及（c）量化对潮汐羽流内羽流综合混合的贡献。本文分析了在低流量、大潮和无风条件下，环境涨潮时形成的羽流。湍流浮力通量（B）和通过羽流的深度积分B（Bd）具有明显的空间异质性。强烈的混合（Bd = 10−5 − 10−4 m3/s3）发生在河口附近、近场烟流转向区、浅滩和近岸浅水区。低到中等混合（Bd = 10−8 − 10−6 m3/s3）占据了羽流的一半。浮力通量首先根据羽流产生的和底部产生的剪切最大值之间的剪切应力最小值的深度进行划分。其他四个测试分区方法是基于明渠流和分层剪切流参数化。界面和底部产生的剪切力有助于不同区域的强烈和适度混合。所有方法都表明，对于底部生成的混合，羽流混合起着重要作用，但界面混合的贡献更大。在最大环境洪水时，羽流综合总混合和界面混合达到峰值，底部产生混合的峰值时间因分区方法而异。三分之二的混合发生在集中的强烈混合区域。以环境潮汐弗劳德数和羽流厚度与深度之比为轴的参数空间表明，许多潮汐调制羽流受到底部产生的潮汐混合的中度至主要影响。
The Connecticut River plume is influenced by energetic ambient tides in the Long Island Sound receiving waters. The objectives of this modeling study are (a) characterizing the spatial heterogeneity of turbulent buoyancy fluxes, (b) partitioning turbulent buoyancy fluxes into bottom‐generated and interfacial shear contributions, and (c) quantifying contributions to plume‐integrated mixing within the tidal plume. The plume formed during ambient flood tides under low river discharge, spring tides, and no winds is analyzed. Turbulent buoyancy fluxes (B) and depth‐integrated B through the plume (Bd) are characterized by pronounced spatial heterogeneity. Strong mixing (Bd ∼ 10−5‐10−4 m3/s3) occurs near the mouth, in the nearfield plume turning region, over shoals, and nearshore shallow areas. Low to moderate mixing (Bd ∼ 10−8‐10−6 m3/s3) occupies half the plume. Buoyancy fluxes are first partitioned based on the depth of the shear stress minimum between plume‐generated and bottom‐generated shear maxima. Four other tested partitioning methods are based on open channel flow and stratified shear flow parameterizations. Interfacial and bottom‐generated shear contribute to different areas of intense and moderate mixing. All methods indicate a significant plume mixing role for bottom‐generated mixing, but interfacial mixing is a bigger contributor. Plume‐integrated total and interfacial mixing peak at max ambient flood and the timing of peak bottom‐generated mixing varies among partitioning methods. Two‐thirds of the mixing occurs in concentrated intense mixing areas. A parameter space with the ambient tidal Froude number and plume thickness to depth ratio as axes indicates many tidally modulated plumes are moderately to dominantly influenced by bottom‐generated tidal mixing.