A mechanism for the increased wave-induced drift of floating marine litter

Calvert, Ross; McAllister, Mark L.; Whittaker, Colin; Raby, Alison; Borthwick, A. G. L.; Bremer, Ton S. van den

doi:10.1017/jfm.2021.72

Cited by 17 publications

(56 citation statements)

References 41 publications

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“…Second, it is well known from observations and LES models that in well-developed Langmuir turbulence the horizontal drift velocity is largest within the surface convergence zones (windrows), where it might reach 150% of the average 37 -and the type of material considered here very likely tends to accumulate in those zones. And finally, yet another mechanism has been described recently 38 , leading to enhanced drift speeds of buoyant objects of large sizes.…”

Section: Discussionmentioning

confidence: 95%

Typical and anomalous pathways of surface-floating material in the northern North Atlantic and Arctic Ocean

Herman

Węsławski

2022

Preprint

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Surface waters of the oceans carry large amounts of material, including sediment grains, plankton organisms, ice crystals, as well as pollutants, e.g., oil and plastic. Transport and spatio-temporal distribution of that material depend on its properties and on the dynamical processes in the ocean mixed layer – currents, waves, turbulence, and convective mixing – acting at a wide range of scales. Due to its importance for marine physics, biogeochemistry and ecology, substantial research effort has been put in recent years into observations and modelling of ocean material transport, especially in the context of marine plastic pollution. Nevertheless, many important questions remain unanswered. In this work, numerically simulated trajectories of surface-floating particles in the period 1993–2020 are used to analyze usual and anomalous transport pathways in the northern North Atlantic and the Arctic Ocean. Lagrangian trajectories are computed based on surface currents from a hydrodynamic model and Stokes drift from a spectral wave model. It is shown that due to high amplitudes of Stokes drift (comparable with wind-induced currents in ice-free parts of the domain of study), combined with its high directional variability, it substantially modifies the drifting paths, underlying the important role of wave-induced currents in surface material transport. A statistical analysis of ∼1.6·108 trajectories reveals patterns of connections between nearshore locations in the domain of study, the associated drift times and path sinuosity. Seasonal variability of transport, different in the Arctic Ocean and the North Atlantic, is found for typical transport routes following the larger-scale circulation patterns. Crucially, in both sub-domains episodic, but very strong transport events between otherwise isolated locations occur, associated with anomalous atmospheric circulation and, arguably, providing ‘windows of opportunity’ for dispersal of various organisms to new locations. It is shown for two examples in the North Atlantic region that an unusual combination of atmospheric circulation indices explains the anomalous transport, thus providing a predictive tool for future events. In the Arctic, analogous phenomena are modified by the state of the sea ice cover.

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Section: Discussionmentioning

confidence: 95%

Typical and anomalous pathways of surface-floating material in the northern North Atlantic and Arctic Ocean

Herman

Węsławski

2022

Preprint

View full text Add to dashboard Cite

show abstract

“…Second, it is well known from observations and LES models that in well-developed Langmuir turbulence, the horizontal drift velocity is largest within the surface convergence zones (windrows), where it might reach 150% of the average 37 —and the type of material considered here very likely tends to accumulate in those zones. And finally, yet another mechanism has been described recently 38 , leading to enhanced drift speeds of buoyant objects of large sizes.…”

Section: Discussionmentioning

confidence: 95%

Typical and anomalous pathways of surface-floating material in the Northern North Atlantic and Arctic Ocean

Herman

Węsławski

2022

Sci Rep

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Surface waters of the oceans carry large amounts of material, including sediment grains, plankton organisms, and ice crystals, as well as pollutants, e.g., oil and plastic. Transport and spatio-temporal distribution of this material depend on its properties and on the dynamical processes in the ocean mixed layer—currents, waves, turbulence, and convective mixing—acting at a wide range of scales. Due to its importance for marine physics, biogeochemistry and ecology, substantial research efforts have been invested in recent years in observations and modelling of ocean material transport, especially in the context of marine plastic pollution. Nevertheless, many important questions remain unanswered. In this work, numerically simulated trajectories of surface-floating particles in the period 1993–2020 are used to analyse typical and anomalous transport pathways in the northern North Atlantic and the Arctic Ocean. Model validation is performed based on additional simulations of 387 buoy tracks from the International Arctic Buoy Programme in the years 2014–2020. The trajectories are computed based on surface currents from a hydrodynamic model and Stokes drift from a spectral wave model. It is shown that due to high amplitudes of Stokes drift (comparable with wind-induced currents in ice-free parts of the domain of study), combined with high directional variability, the drifting paths are substantially modified in ice-free regions, underlying the important role of wave-induced currents in surface material transport. A statistical analysis of $$\sim 1.6\, 10^8$$ ∼ 1.6 10 8 trajectories reveals patterns of connections between nearshore locations in the domain of study, the associated drift times and path sinuosity. Seasonal variability of transport, which differs between the Arctic Ocean and the North Atlantic, is found for typical transport routes following the larger-scale circulation patterns. Crucially, in both sub-domains episodic, but very strong transport events between otherwise isolated locations occur, associated with anomalous atmospheric circulation and, arguably, providing ‘windows of opportunity’ for dispersal of various organisms to new locations. It is shown for two examples in the North Atlantic region that an unusual combination of atmospheric circulation indices explains the anomalous transport, thus providing a predictive tool for future events. In the Arctic, analogous phenomena are modified by the state of the sea ice cover.

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“…Prior to breaking, the particles can be expected to move with a velocity near the waveinduced Lagrangian fluid particle velocity (see e.g. Alsina et al, 2020;Calvert et al, 2021), here approximated as Eq. ( 7).…”

Section: Beaching Times and Lagrangian Transport Velocitiesmentioning

confidence: 99%

“…Pizzo (2017) utilized the same model as Deike et al (2017) and derived a criterion for when particles "surf" on the breaking wave, making them travel approximately at the wave celerity. Recently, Calvert et al (2021) described analytically how relatively large particles can be expected to travel at velocities above those predicted by the Stokes drift in non-breaking deep-water waves.…”

Section: Introductionmentioning

confidence: 99%

“…In the above studies the particles were either considered as passive tracers (Deike et al, 2017;Pizzo, 2017) or were larger than the microplastic regime (Lenain et al, 2019;Calvert et al, 2021). Furthermore, the studies focused on deep-water waves, whereas there have been relatively few studies focusing on the transport mechanisms of buoyant microplastic particles in nearshore coastal regions (van Sebille et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Experimental investigation on the nearshore transport of buoyant microplastic particles

Larsen

Al-Obaidi

Güler

et al. 2023

Marine Pollution Bulletin

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A mechanism for the increased wave-induced drift of floating marine litter

Abstract: Abstract

Cited by 17 publications

References 41 publications

Typical and anomalous pathways of surface-floating material in the northern North Atlantic and Arctic Ocean

Typical and anomalous pathways of surface-floating material in the northern North Atlantic and Arctic Ocean

Typical and anomalous pathways of surface-floating material in the Northern North Atlantic and Arctic Ocean

Experimental investigation on the nearshore transport of buoyant microplastic particles

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