Particles in motion: How turbulence affects plankton sedimentation from an oceanic mixed layer

Ross, Oliver N.

doi:10.1029/2006gl026352

Cited by 30 publications

(49 citation statements)

References 24 publications

(37 reference statements)

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“…The suspension and drift of buoyant particles, such as oil spills and biological matters, within an oscillatory turbulent fluid are frequently observed phenomena in a number of geophysical and offshore engineering applications (Murray 1970;Fowler and Knauer 1986;Wilson 2000;Ross 2010;Drivdal et al 2014). While light particles, i.e., bubbles, exhibit strong tendency to trap in the high vorticity regions near the air-sea interface, heavy inertial particles (with diameter > 200 μm) sink to the deep ocean due to their tendency to accumulate in the regions of high strain rate and low vorticity.…”

Section: Introductionmentioning

confidence: 99%

Turbulence-particle interactions under surface gravity waves

Paskyabi

2016

Ocean Dynamics

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The dispersion and transport of single inertial particles through an oscillatory turbulent aquatic environment are examined numerically by a Lagrangian particle tracking model using a series of idealised test cases. The turbulent mixing is incorporated into the Lagrangian model by the means of a stochastic scheme in which the inhomogeneous turbulent quantities are governed by a onedimensional k-ε turbulence closure scheme. This vertical mixing model is further modified to include the effects of surface gravity waves including Coriolis-Stokes forcing, wave breaking, and Langmuir circulations. To simplify the complex interactions between the deterministic and the stochastic phases of flow, we assume a time-invariant turbulent flow field and exclude the hydrodynamic biases due to the effects of ambient mean current. The numerical results show that the inertial particles acquire perturbed oscillations traced out as time-varying sinking/rising orbits in the vicinity of the sea surface under linear and cnoidal waves and acquire a non-looping single arc superimposed with the high-frequency fluctuations beneath the nonlinear solitary waves. Furthermore, we briefly summarise some recipes through the course of this paper on the implementation of the stochastic particle tracking models to realistically describe the drift and suspension of inertial particles throughout the water column.

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Section: Introductionmentioning

confidence: 99%

Turbulence-particle interactions under surface gravity waves

Paskyabi

2016

Ocean Dynamics

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“…In previous studies, apparently conflicting conclusions were even presented by various authors (e.g. Lande and Wood, 1987;Maxey, 1987;Fung, 1993;Wang and Maxey, 1993;Ruiz, 1996;Franks, 2001;Deleersnijder et al, 2006a;Ross, 2006).…”

Section: Accepted M M a N U mentioning

confidence: 94%

“…Delhez et al, 2004;Ross, 2006;Delhez, 2006). This approach is not fully appropriate when the aim is to quantify the effect of diffusion on the survival of phytoplankton.…”

Section: Residence Time In the Euphotic Layermentioning

confidence: 99%

“…Lande and Wood, 1987;Ruiz, 1996;Franks, 2001;Deleersnijder et al, 2006a;Ross, 2006) the growth rate is not included in the equation (9). The light conditions encountered by the cells during their vertical movements and their influence on the growth rate are however considered in section 5.…”

Section: Residence Time In the Euphotic Layermentioning

confidence: 99%

“…Maxey, 1987;Wang and Maxey, 1993;Franks, 2001). Using a random walk model, Ross (2006) computed the residence time in the surface mixed layer of a 1D vertical model of the water column. His numerical results suggest that turbulence increases the residence time.…”

Section: Residence Time In the Euphotic Layermentioning

confidence: 99%

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Residence time and exposure time of sinking phytoplankton in the euphotic layer

Delhez

Deleersnijder

2010

Journal of Theoretical Biology

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The residence time of a sinking particle in the euphotic layer is usually defined as the time taken by this particle to reach for the first time the bottom of the euphotic layer. According to this definition, the concept of residence time does not take into account the fact that many cells leaving the euphotic layer at some time can re-enter the euphotic layer at a later time. Therefore, the exposure time in the surface layer, i.e. the total time spent by the particles in the euphotic layer irrespective of their possible excursions outside the surface layer, is a more relevant concept to diagnose the effect of diffusion on the survival of phytoplankton cells sinking through the water column.While increasing the diffusion coefficient can induce both a decrease or an increase of the residence time, the exposure time in the euphotic layer increases monotonically with the diffusion coefficient, at least when the settling velocity does not increase with depth. Turbulence is therefore shown to increase the total time spent by phytoplankton cells in the euphotic layer.The generalization of the concept of exposure time to take into account the variations of the light intensity with depth or the functional response of phytoplankton cells to irradiance leads to the definition of the concepts of light exposure and effective light exposure. The former provides a measure of the total light energy received by the cells during their cycling through the water column while the latter diagnose the potential growth rate.The exposure time, the light exposure and the effective light exposure can all be computed as the solution of a differential problem that generalizes the adjoint approach introduced by Delhez et al. (2004) for the residence time. A general analytical solution of the 1D steady-state version of this equation is derived from which the properties of the different diagnostic tools can be obtained.

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Particle distributions and dynamics in the euphotic zone of the North Pacific Subtropical Gyre

et al. 2015

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During the summer of 2012, we used laser diffractometry to investigate the temporal and vertical variability of the particle size spectrum (1.25–100 µm in equivalent diameter) in the euphotic zone of the North Pacific Subtropical Gyre. Particles measured with this optical method accounted for ∼40% of the particulate carbon stocks (<202 µm) in the upper euphotic zone (25–75 m), as estimated using an empirical formula to transform particle volume to carbon concentrations. Over the entire vertical layer considered (20–180 m), the largest contribution to particle volume corresponded to particles between 3 and 10 µm in diameter. Although the exponent of a power law parameterization suggested that larger particles had a lower relative abundance than in other regions of the global ocean, this parameter and hence conclusions about relative particle abundance are sensitive to the shape of the size distribution and to the curve fitting method. Results on the vertical distribution of particles indicate that different size fractions varied independently with depth. Particles between 1.25 and 2 µm reached maximal abundances coincident with the depth of the chlorophyll a maximum (averaging 121 ± 10 m), where eukaryotic phytoplankton abundances increased. In contrast, particles between 2 and 20 µm tended to accumulate just below the base of the mixed layer (41 ± 14 m). Variability in particle size tracked changes in the abundance of specific photoautotrophic organisms (measured with flow cytometry and pigment concentration), suggesting that phytoplankton population dynamics are an important control of the spatiotemporal variability in particle concentration in this ecosystem.

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Particles in motion: How turbulence affects plankton sedimentation from an oceanic mixed layer

Cited by 30 publications

References 24 publications

Turbulence-particle interactions under surface gravity waves

Turbulence-particle interactions under surface gravity waves

Residence time and exposure time of sinking phytoplankton in the euphotic layer

Particle distributions and dynamics in the euphotic zone of the North Pacific Subtropical Gyre

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