A mechanism for the increased wave-induced drift of floating marine litter
Periodic water waves generate Stokes drift as manifest from the orbits of Lagrangian particles not fully closing. Stokes drift can contribute to the transport of floating marine litter, including plastic. Previously, marine litter objects have been considered to be perfect Lagrangian tracers, travel...
| Main Authors: | , , , , , |
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| Format: | Journal article |
| Sprog: | English |
| Udgivet: |
Cambridge University Press
2021
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| _version_ | 1826266445277822976 |
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| author | Calvert, R McAllister, M Whittaker, C Raby, A Borthwick, A Van Den Bremer, TS |
| author_facet | Calvert, R McAllister, M Whittaker, C Raby, A Borthwick, A Van Den Bremer, TS |
| author_sort | Calvert, R |
| collection | OXFORD |
| description | Periodic water waves generate Stokes drift as manifest from the orbits of Lagrangian particles not fully closing. Stokes drift can contribute to the transport of floating marine litter, including plastic. Previously, marine litter objects have been considered to be perfect Lagrangian tracers, travelling with the Stokes drift of the waves. However, floating marine litter objects have large ranges of sizes and densities, which potentially result in different rates of transport by waves due to the non-Lagrangian behaviour of the objects. Through a combination of theory and experiments for idealised spherical objects in deep-water waves, we show that different objects are transported at different rates depending on their size and density, and that larger buoyant objects can have increased drift compared with Lagrangian tracers. We show that the mechanism for the increased drift observed in our experiments comprises the variable submergence and the corresponding dynamic buoyancy force components in a direction perpendicular to the local water surface. This leads to an amplification of the drift of these objects compared to the Stokes drift when averaged over the wave cycle. Using an expansion in wave steepness, we derive a closed-form approximation for this increased drift, which can be included in ocean-scale models of marine litter transport. |
| first_indexed | 2024-03-06T20:39:04Z |
| format | Journal article |
| id | oxford-uuid:33a72c1c-6f52-49ef-8b3d-f9c3d62f8bbb |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-06T20:39:04Z |
| publishDate | 2021 |
| publisher | Cambridge University Press |
| record_format | dspace |
| spelling | oxford-uuid:33a72c1c-6f52-49ef-8b3d-f9c3d62f8bbb2022-03-26T13:21:23ZA mechanism for the increased wave-induced drift of floating marine litterJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:33a72c1c-6f52-49ef-8b3d-f9c3d62f8bbbEnglishSymplectic ElementsCambridge University Press2021Calvert, RMcAllister, MWhittaker, CRaby, ABorthwick, AVan Den Bremer, TSPeriodic water waves generate Stokes drift as manifest from the orbits of Lagrangian particles not fully closing. Stokes drift can contribute to the transport of floating marine litter, including plastic. Previously, marine litter objects have been considered to be perfect Lagrangian tracers, travelling with the Stokes drift of the waves. However, floating marine litter objects have large ranges of sizes and densities, which potentially result in different rates of transport by waves due to the non-Lagrangian behaviour of the objects. Through a combination of theory and experiments for idealised spherical objects in deep-water waves, we show that different objects are transported at different rates depending on their size and density, and that larger buoyant objects can have increased drift compared with Lagrangian tracers. We show that the mechanism for the increased drift observed in our experiments comprises the variable submergence and the corresponding dynamic buoyancy force components in a direction perpendicular to the local water surface. This leads to an amplification of the drift of these objects compared to the Stokes drift when averaged over the wave cycle. Using an expansion in wave steepness, we derive a closed-form approximation for this increased drift, which can be included in ocean-scale models of marine litter transport. |
| spellingShingle | Calvert, R McAllister, M Whittaker, C Raby, A Borthwick, A Van Den Bremer, TS A mechanism for the increased wave-induced drift of floating marine litter |
| title | A mechanism for the increased wave-induced drift of floating marine litter |
| title_full | A mechanism for the increased wave-induced drift of floating marine litter |
| title_fullStr | A mechanism for the increased wave-induced drift of floating marine litter |
| title_full_unstemmed | A mechanism for the increased wave-induced drift of floating marine litter |
| title_short | A mechanism for the increased wave-induced drift of floating marine litter |
| title_sort | mechanism for the increased wave induced drift of floating marine litter |
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