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首页> 外文期刊>Journal of Physical Oceanography >The Scaling and Structure of the Estuarine Bottom Boundary Layer
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The Scaling and Structure of the Estuarine Bottom Boundary Layer

机译：河口底部边界层的尺度和结构

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A two-week dataset from a partially and periodically stratified estuary quantifies variability in the turbulence across the tidal and spring-neap time scales. These observations have been fit with a two-parameter model of the Reynolds stress profile, which produces estimates of the time variation of the bottom boundary layer height and the friction velocity. Conditions at the top of the bottom boundary layer indicate that the dynamics governing the development of the estuarine bottom boundary layer are different on ebb tides than on flood tides. The asymmetry in the flow is explained by consideration of the strain-induced buoyancy flux, which is stabilizing on ebb tides and destabilizing on flood tides. Based on these observations, a scaling approach to estimating estuarine bottom boundary layer parameters (height and friction velocity) is presented, which includes a modified Monin-Obukhov length scale to account for the horizontal buoyancy flux created by the sheared advection. Comparison with the observations of boundary layer height and friction velocity suggests that this approach may be successful in predicting bottom boundary layer parameters in estuaries and coastal regions with significant horizontal buoyancy fluxes. Comparison between the strain-induced buoyancy flux and shear production indicates that the straining of the density field is an important contributor to the turbulent kinetic energy budget and creates an asymmetry in turbulent energy between ebb and flood tides. It appears that the structure of the turbulence, specifically the ratio of the Reynolds stress to the turbulent energy, is also modified by tidal straining, further accentuating the ebb-flood asymmetries.
机译：来自部分且定期分层的河口的为期两周的数据集量化了潮汐和春季需求时间尺度上的湍流变化。这些观察结果与雷诺应力分布的两参数模型相吻合，该模型可以估算出底部边界层高度和摩擦速度随时间的变化。底部边界层顶部的条件表明，控制河口底部边界层发展的动力学在退潮时与洪水潮时不同。通过考虑由应变引起的浮力通量来解释流动中的不对称性，该通量在潮汐时稳定，而在潮汐时不稳定。基于这些观察，提出了一种估算河口底部边界层参数（高度和摩擦速度）的缩放方法，其中包括修改后的Monin-Obukhov长度比例尺，以说明剪切对流产生的水平浮力。与边界层高度和摩擦速度观测值的比较表明，这种方法可能成功地预测了具有明显水平浮力通量的河口和沿海地区的底部边界层参数。应变引起的浮力通量和剪切产生之间的比较表明，密度场的应变是湍动能预算的重要贡献，并且在潮汐和潮汐之间产生了不对称的湍流能。看来湍流的结构，特别是雷诺应力与湍流能量之比，也被潮汐应变所改变，进一步加剧了潮汐不对称性。

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