High frequency variability of particle size distribution and its dependency on turbulence over the sea bottom during re-suspension processes

Renosh, Pannimpullath Remanan; Schmitt, François G; Loisel, Hubert; Sentchev, Alexei; Mériaux, Xavier

doi:10.1016/j.csr.2014.01.024

Cited by 21 publications

(24 citation statements)

References 49 publications

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“…In this study, we investigated the PSD spatial distribution of the study area based on in situ laser diffraction measurements during November 2013. Note that the observation stations were actually investigated on different dates and time during a month, and so some factors such as tidal current, waves and turbulence [25][26][27][28], might show a certain impact on temporal variability of PSD. However, it is very difficult to do synchronous observation on all these stations in the investigated water areas, which limits the plot of spatial distribution in a rigorously simultaneous manner.…”

Section: Discussionmentioning

confidence: 99%

Variability of Particle Size Distributions in the Bohai Sea and the Yellow Sea

Qiu

Sun

et al. 2016

Remote Sensing

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Particle size distribution (PSD) is an important parameter that is relevant to many aspects of marine ecosystems, such as phytoplankton functional types, optical absorption and scattering from particulates, sediment fluxes, and carbon export. However, only a handful of studies have documented the PSD variability in different regions. Here, we investigate the PSD properties and variability in two shallow and semi-enclosed seas (the Bohai Sea (BS) and Yellow Sea (YS)), using in situ laser diffraction measurements (LISST-100X Type C) and other measurements at 79 stations in November 2013. The results show large variability in particle concentrations (in both volume and number concentrations), with volume concentrations varying by 57-fold. The median particle diameter (D v 50 ) from each of the water samples also covers a large range (22.4-307.0 µm) and has an irregular statistical distribution, indicating complexity in the PSD. The PSD slopes (2.7-4.5), estimated from a power-law model, cover nearly the entire range reported previously for natural waters. Small mineral particles (with large PSD slopes) are characteristic of near-shore waters prone to sediment resuspension by winds and tides, while large biological particles (with small PSD slopes) dominate the total suspended particulates for waters away from the coast. For the BS and YS, this study provides the first report on the properties and spatial variability of the PSD, which may influence the optical properties of the ocean surface and remote sensing algorithms that are based on estimations of particle concentrations and sizes.

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Section: Discussionmentioning

confidence: 99%

Variability of Particle Size Distributions in the Bohai Sea and the Yellow Sea

Qiu

Sun

et al. 2016

Remote Sensing

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“…For the present study we consider four different size classes, using the following classification: silt/clay (σ < 30 µm), fine (30 < σ < 105 µm), coarse/micro (105 < σ < 300 µm) and macro flocs/particles (σ > 300 µm) (Lefebvre et al, 2012;Renosh et al, 2014). Figure 2 shows the time series of normalised volume concentrations (VC) of different size classes of PSD.…”

Section: Separation Into Size Classesmentioning

confidence: 99%

“…The shape of the PSD is also used in computing the sinking rate of the sediment fluxes. The study carried out by Renosh et al (2014) using the same in situ data set as the present study showed that the dynamics of the PSD is controlled by many oceanographic parameters like tidal currents, waves, and turbulence. The present study is a continuation of this work.…”

Section: Introductionmentioning

confidence: 99%

“…3b with a slope value of ξ = 2.9 ± 0.16. The study carried out by Renosh et al (2014) considered the dynamics of the ξ(t) in relation to different hydrodynamic quantities like waves, tidal currents and turbulence. It showed that turbulence has a major role in the re-suspension of the particles in the aquatic environment.…”

Section: Psd Slope (ξ )mentioning

confidence: 99%

“…The PSD of this density number classically follows a powerlaw distribution for aquatic particles in suspension (Sheldon et al, 1972;Kitchen et al, 1982;Jonaszz, 1983;Boss et al, 2001;Loisel et al, 2006;Reynolds et al, 2010;Renosh et al, 2014):…”

Section: Psd Slope (ξ )mentioning

confidence: 99%

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Intermittent particle dynamics in marine coastal waters

Renosh

Schmitt

Loisel

2015

Nonlin. Processes Geophys.

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Abstract. 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 C vol-total and the particulate beam attenuation coefficient c p (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.

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Vertical convergence of resuspended sediment and subducted phytoplankton to a persistent detached layer over the southern shelf of Monterey Bay, California

et al. 2015

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Work done by the present authors and collaborators in the first year of a 2‐year field study established the frequent presence of layers of suspended particulate matter detached from the seafloor over the southern shelf of Monterey Bay, California. In this contribution, we document similar findings over a 1‐month period in Fall 2012 and investigate physical processes leading to vertical convergence of particles to the observed layers, both from resuspended sediment originating below the layer depth and from phytoplankton originating above the layer depth. Physical and optical vertical structure was measured by an autonomous vertical profiler, thermistor chain, and acoustic Doppler current profiler, and optical sensors fixed to a bottom‐mounted frame measured beam attenuation and particle size distribution within the benthic boundary layer (BBL). These data support a conceptual model for layer formation in which (1) bottom material was mobilized into the BBL by semidiurnal internal tidal currents; (2) brief “updraft” events regularly injected particles into the interior water column during the downslope phase of the semidiurnal internal tide; and (3) particles converged at the detached layer due to a measured, but previously unreported, long time scale mean vertical convergence in flow. Subduction and vertical mixing of phytoplankton to the subeuphotic layer were also observed and are presented in two case studies in connection with horizontal convergences of surface water masses.

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High frequency variability of particle size distribution and its dependency on turbulence over the sea bottom during re-suspension processes

Cited by 21 publications

References 49 publications

Variability of Particle Size Distributions in the Bohai Sea and the Yellow Sea

Variability of Particle Size Distributions in the Bohai Sea and the Yellow Sea

Intermittent particle dynamics in marine coastal waters

Vertical convergence of resuspended sediment and subducted phytoplankton to a persistent detached layer over the southern shelf of Monterey Bay, California

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