The Multi-Scale Layering-Structure of Thermal Microscale Profiles
The Multi-Scale Layering-Structure of Thermal Microscale Profiles
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DOI：
10.3390/w13213042
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发表时间：
2021-11
期刊：
影响因子：
3.4
通讯作者：
A. Folkard
中科院分区：
文献类型：
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作者：
A. Folkard
热微结构剖面分析是一种用于研究湖泊和海洋中湍流混合和分层的成熟技术。然而，它只提供准瞬时的1-D快照。存在其他衡量这些现象的方法，但每种方法都有逻辑和/或质量方面的弱点。因此，湍流混合和分层过程仍然大大采样不足。本文有助于解决这个问题，提出了一种新的分析热微观结构的配置文件，专注于他们的多尺度分层结构。在两个小湖使用自包含的自动化微剖面仪（SCAMP）的配置文件进行了分析。对于每个配置文件，浮力频率（N），索普尺度（LT），和垂直湍流扩散系数（KZ）进行了测定。为了表征多尺度分层，计算了一系列尺度下的d2 T/dz 2曲线，并计算了其中的转折点数量。将这些计数与标度作图得到伪谱，其特征在于其幂律回归线的指数D。尺度相关的D与N，LT和KZ被发现，并建议这种方法可能是有用的，提供替代估计的湍流混合的效率和措施的长期平均KZ比目前的方法提供。测试这些潜在的用途将需要比较D的现场测量值与时间积分KZ值和数值模拟。
Thermal microstructure profiling is an established technique for investigating turbulent mixing and stratification in lakes and oceans. However, it provides only quasi-instantaneous, 1-D snapshots. Other approaches to measuring these phenomena exist, but each has logistic and/or quality weaknesses. Hence, turbulent mixing and stratification processes remain greatly under-sampled. This paper contributes to addressing this problem by presenting a novel analysis of thermal microstructure profiles, focusing on their multi-scale stratification structure. Profiles taken in two small lakes using a Self-Contained Automated Micro-Profiler (SCAMP) were analysed. For each profile, buoyancy frequency (N), Thorpe scales (LT), and the coefficient of vertical turbulent diffusivity (KZ) were determined. To characterize the multi-scale stratification, profiles of d2T/dz2 at a spectrum of scales were calculated and the number of turning points in them counted. Plotting these counts against the scale gave pseudo-spectra, which were characterized by the index D of their power law regression lines. Scale-dependent correlations of D with N, LT and KZ were found, and suggest that this approach may be useful for providing alternative estimates of the efficiency of turbulent mixing and measures of longer-term averages of KZ than current methods provide. Testing these potential uses will require comparison of field measurements of D with time-integrated KZ values and numerical simulations.