Interpreting Fixed-Location Observations of Turbulence Advected by Waves: Insights from Spectral Models
Interpreting Fixed-Location Observations of Turbulence Advected by Waves: Insights from Spectral Models
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DOI：
10.1175/jpo-d-15-0249.1
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发表时间：
2017-04
影响因子：
3.5
通讯作者：
Johanna H. Rosman;G. Gerbi
中科院分区：
文献类型：
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作者：
Johanna H. Rosman;G. Gerbi
摘要由于非定常波轨道运动对涡旋的平流作用，对波下的湍流波动进行物理解释是很复杂的。本文利用模型湍流空间谱(κ谱)和冻结湍流近似的一般形式，研究了波浪轨道运动对固定位置湍流涨落的运动学效应。模式自谱和共谱包括一个惯性子范围、一个含能尺度(L=2π/κ0)的滚降和一个耗散范围。湍流是由平行于电流UC传播的波(均方根轨道速度σw、峰值频率ωw和谱宽度Δωw)组成的背景流平流。推导了湍流频谱(ω谱)的表达式，参数在沿海海洋的典型范围内是不同的。除接近频段外，ω谱形状随速度比σw/uc和时间尺度比ucκ0/ωw这两个无量纲参数而崩塌，这两个参数可用来诊断地震波。
AbstractAssigning a physical interpretation to turbulent fluctuations beneath waves is complex because eddies are advected by unsteady wave orbital motion. Here, the kinematic effects of wave orbital motion on turbulent fluctuations at a fixed location were investigated using model turbulence spatial spectra (κ spectra) together with a general form of the frozen turbulence approximation. Model autospectra and cospectra included an inertial subrange, a rolloff at energy-containing scales (L = 2π/κ0), and a dissipation range. Turbulence was advected by a background flow composed of waves (rms orbital velocity σw, peak frequency ωw, and spectral width Δωw) propagating parallel to a current uc. Expressions were derived for turbulence frequency spectra (ω spectra), and parameters were varied across ranges typical in the coastal ocean. Except close to the wave band, the ω-spectrum shape collapses with two dimensionless parameters, a velocity ratio σw/uc, and a time-scale ratio ucκ0/ωw, which can be used to diag...