Non-breaking Wave Effects on Buoyant Particle Distributions
Non-breaking Wave Effects on Buoyant Particle Distributions
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DOI：
10.3389/fmars.2020.00148
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发表时间：
2020-03-19
影响因子：
3.7
通讯作者：
DiBenedetto, Michelle H.
中科院分区：
文献类型：
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作者：
DiBenedetto, Michelle H.
海洋混合层中漂浮颗粒的扩散受到多种物理因素的影响，包括风、浪和湍流。微塑料观测通常在自由表面进行，而自由表面受到表面重力波的强烈作用。许多研究利用数值模拟来研究湍流和波浪效应（例如破碎波、朗缪尔环流）如何控制海洋表面漂浮颗粒的扩散。然而，这些模拟并不能解析波浪的相位。因此，在这种情况下，由于表面重力波导致的不稳定自由表面的影响仍然未知。为了解决这个问题，我们针对深水中风浪条件下漂浮颗粒随波相的分布建立了一个解析模型。利用这个解析模型以及互补的数值模拟，我们量化了非破碎、单色、前进波列对漂浮颗粒平衡垂直分布和水平分布的影响。我们发现，波浪导致颗粒的水平分布不均匀，波峰下的颗粒比波谷下的多。我们还发现，波浪能够拉伸或压缩平衡垂直分布。最后，我们考虑了波浪对用拖网采集微塑料的影响，并且我们表明，相对于不受波浪影响的拖网采样，波浪能够降低所测量到的浓度。
The dispersal of buoyant particles in the ocean mixed layer is influenced by a variety of physical factors including wind, waves, and turbulence. Microplastics observations are often made at the free surface, which is strongly forced by surface gravity waves. Many studies have used numerical simulations to examine how turbulence and wave effects (e.g., breaking waves, Langmuir circulation) control buoyant particle dispersal at the ocean surface. However these simulations are not wave phase-resolving. Therefore, the effects of an unsteady free surface due to surface gravity waves remain unknown in this context. To address this, we develop an analytical model for the distribution of buoyant particles as a function of wave-phase under wind-wave conditions in deep-water. Using this analytical model and complementary numerical simulations, we quantify the effects of a nonbreaking, monochromatic, progressive wave train on the equilibrium vertical and horizontal distributions of buoyant particles. We find that waves result in non-uniform horizontal distributions of particles with more particles under the wave crests than the troughs. We also find that the waves can stretch or compress the equilibrium vertical distribution. Finally, we consider the effects of waves on the sampling of microplastics with a towed net, and we show that waves have the ability to lower the measured concentrations relative to nets sampling without the influence of waves.