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Intermittent particle dynamics in marine coastal waters

机译：海洋沿海水域中的间歇性粒子动力学

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Marine coastal processes are highly variable over different space scales and timescales. In this paper we analyse the intermittency properties of particle size distribution (PSD) recorded every second using a LISST instrument (Laser In-Situ Scattering and Transmissometry). The particle concentrations have been recorded over 32 size classes from 2.5 to 500 μm, at 1 Hz resolution. Such information is used to estimate at each time step the hyperbolic slope of the particle size distribution, and to consider its dynamics. Shannon entropy, as an indicator of the randomness, is estimated at each time step and its dynamics is analysed. Furthermore, particles are separated into four classes according to their size, and the intermittent properties of these classes are considered. The empirical mode decomposition (EMD) is used, associated with arbitrary-order Hilbert spectral analysis (AHSA), in order to retrieve scaling multifractal moment functions, for scales from 10 s to 8 min. The intermittent properties of two other indicators of particle concentration are also considered in the same range of scales: the total volume concentration iC/isubvol-total/sub and the particulate beam attenuation coefficient ic/isubp/sub(670). Both show quite similar intermittent dynamics and are characterised by the same exponents. Globally we find here negative Hurst exponents (meaning the small scales show larger fluctuation than large scales) for each time series considered, and nonlinear moment functions.
机译：海洋沿海过程在不同的空间尺度和时间尺度上变化很大。在本文中，我们分析了使用LISST仪器（激光原位散射和透射法）每秒记录的粒度分布（PSD）的间歇性。在1 Hz分辨率下，已经记录了2.5至500μm的32种尺寸级别的颗粒浓度。此类信息用于估计每个时间步长的粒度分布的双曲线斜率，并考虑其动力学。在每个时间步长估计香农熵作为随机性的指标，并分析其动力学。此外，根据粒子的大小将其分为四个类别，并考虑这些类别的间歇性。使用经验模式分解（EMD），并与任意阶数的希尔伯特频谱分析（AHSA）关联，以获取标度多重分形矩函数，标度为10 s至8 min。在相同的尺度范围内，还考虑了其​​他两个粒子浓度指标的间歇特性：总体积浓度 C vol-total 和粒子束衰减系数 c p （670）。两者都显示出非常相似的间歇动力学，并且具有相同的指数特征。在全球范围内，对于每个考虑的时间序列，我们都在这里发现负的赫斯特指数（意味着小尺度的波动大于大尺度的波动）以及非线性矩函数。

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