The negative role of turbulence in estuarine mass transport
The negative role of turbulence in estuarine mass transport
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DOI：
10.1016/0272-7714(89)90085-1
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发表时间：
1989-04
影响因子：
2.8
通讯作者：
Richard A. Nunes Vaz;G. Lennon;Jayantha R. de Silva Samarasinghe
中科院分区：
文献类型：
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作者：
Richard A. Nunes Vaz;G. Lennon;Jayantha R. de Silva Samarasinghe
各种分层和混合影响之间的竞争决定了河口的分层特征。借用已成功应用于陆架海分层讨论的概念，导出了确定河口垂直结构有关势能的定量基础。该公式与Bowden（1981）的公式类似，提供了一种简单而全面的方法，将许多相关的分层和混合影响纳入给定问题中，并且还显示能够重新排列成类似于河口Richardson数的形式，该形式在河口分层的讨论中经常发现。在查阅文献的基础上，本文认为，在较宽、相对混合较好的河口，最大的纵向质量通量出现在分层最发达的时候，即水柱中的湍流动能最小的时候。湍流的调制，主要是在各种潮汐频率上，引起质量通量的脉冲，其中每个脉冲的贡献随着调制周期的增加而非线性地增加。在淡水期，可能会发生分层状态和相应质量输运的一些可能是重要的变化。然而，春季-小潮周期被认为对河口的分层、物质输送和长期物质平衡有更大的影响，最近的观测研究支持了这一观点。
It is competition between the various stratifying and mixing influences which determines the character of stratification in an estuary. Borrowing concepts which have been successfully applied to the discussion of stratification in shelf seas, a quantitative basis for determining the potential energy associated with vertical structure in estuaries is derived. The formulation, along similar lines to that of Bowden (1981), provides a simple but comprehensive method of incorporating many relevant stratifying and mixing influences in a given problem, and is also shown to be capable of rearrangement into forms akin to the estuarine Richardson number which is commonly found in discussions of estuarine statification.The paper argues, based on a survey of the literature, that in wide, relatively well-mixed estuaries, the greatest longitudinal mass flux occurs at times when stratification is most developed, that is, when the turbulent kinetic energy in the water column is at a minimum. Modulation of turbulence, principally at various tidal frequencies, causes a pulsing of the mass flux in which the contribution of each pulse increases non-linearly as the period of the modulation increases. Some, possibly significant, changes to the state of stratification and to the corresponding mass transport may occur in association with slack water periods. However, the spring-neap cycle is proposed to have a far greater influence on stratification, mass transport and the long-term mass balance in estuaries, and recent observational studies lend support to this position.