Research and Development Center for Global Change, Japan Agency for Marine-Earth Science and Technology, Yokosuka, Japan.
Atmosphere and Ocean Research Institute, University of Tokyo, Chiba, Japan.
Sci Rep. 2020 Nov 23;10(1):20414. doi: 10.1038/s41598-020-77414-2.
Energy dissipation rates are an important characteristic of turbulence; however, their magnitude in observational profiles can be incorrectly determined owing to their irregular appearance during vertical evolution. By analysing the data obtained from oceanic turbulence measurements, we demonstrate that the vertical sequences of energy dissipation rates exhibit a scaling property. Utilising this property, we propose a method to estimate the population mean for a profile. For scaling in the observed profiles, we demonstrate that our data exhibit a statistical property consistent with that exhibited by the universal multifractal model. Meanwhile, the population mean and its uncertainty can be estimated by inverting the probability distribution obtained by Monte Carlo simulations of a cascade model; to this end, observational constraints from several moments are imposed over each vertical sequence. This approach enables us to determine, to some extent, whether a profile shows an occasionally large mean or whether the population mean itself is large. Thus, it will contribute to the refinement of the regional estimation of the ocean energy budget, where only a small amount of turbulence observation data is available.
能量耗散率是湍流的一个重要特征；然而，由于其在垂直演化过程中不规则的出现，观测剖面中的能量耗散率的大小可能会被错误地确定。通过分析从海洋湍流测量中获得的数据，我们证明能量耗散率的垂直序列具有标度性质。利用这一性质，我们提出了一种估计剖面总体均值的方法。对于观察到的剖面中的标度，我们证明我们的数据表现出与普遍多重分形模型一致的统计性质。同时，通过对级联模型的蒙特卡罗模拟得到的概率分布进行反演，可以估计总体均值及其不确定性；为此，对每个垂直序列施加了几个矩的观测约束。这种方法可以在一定程度上确定一个剖面是否偶尔出现较大的均值，或者总体均值本身是否较大。因此，它将有助于完善区域海洋能量预算的估计，而区域海洋能量预算的估计仅可利用少量的湍流观测数据。
