Internal Tides Drive Nutrient Fluxes Into the Deep Chlorophyll Maximum Over Mid-ocean Ridges
Diapycnal mixing of nutrients from the thermocline to the surface sunlit ocean is thought to be relatively weak in the world's subtropical gyres as energy inputs from winds are generally low. The interaction of internal tides with rough topography enhances diapycnal mixing, yet the role of tida...
Published in: | Global Biogeochemical Cycles |
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Format: | Article in Journal/Newspaper |
Language: | English |
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Amer Geophysical Union
2019
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Online Access: | https://archimer.ifremer.fr/doc/00763/87475/92972.pdf https://archimer.ifremer.fr/doc/00763/87475/92973.docx https://doi.org/10.1029/2019GB006214 https://archimer.ifremer.fr/doc/00763/87475/ |
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ftarchimer:oai:archimer.ifremer.fr:87475 2023-05-15T17:37:04+02:00 Internal Tides Drive Nutrient Fluxes Into the Deep Chlorophyll Maximum Over Mid-ocean Ridges Tuerena, Robyn E. Williams, Richard G. Mahaffey, Claire Vic, Clement Green, J. A. Mattias Naveira-garabato, Alberto Forryan, Alexander Sharples, Jonathan 2019-08 application/pdf https://archimer.ifremer.fr/doc/00763/87475/92972.pdf https://archimer.ifremer.fr/doc/00763/87475/92973.docx https://doi.org/10.1029/2019GB006214 https://archimer.ifremer.fr/doc/00763/87475/ eng eng Amer Geophysical Union https://archimer.ifremer.fr/doc/00763/87475/92972.pdf https://archimer.ifremer.fr/doc/00763/87475/92973.docx doi:10.1029/2019GB006214 https://archimer.ifremer.fr/doc/00763/87475/ info:eu-repo/semantics/openAccess restricted use Global Biogeochemical Cycles (0886-6236) (Amer Geophysical Union), 2019-08 , Vol. 33 , N. 8 , P. 995-1009 mixing nitrate tides nutrients Atlantic gyre text Publication info:eu-repo/semantics/article 2019 ftarchimer https://doi.org/10.1029/2019GB006214 2022-04-19T22:50:01Z Diapycnal mixing of nutrients from the thermocline to the surface sunlit ocean is thought to be relatively weak in the world's subtropical gyres as energy inputs from winds are generally low. The interaction of internal tides with rough topography enhances diapycnal mixing, yet the role of tidally induced diapycnal mixing in sustaining nutrient supply to the surface subtropical ocean remains relatively unexplored. During a field campaign in the North Atlantic subtropical gyre, we tested whether tidal interactions with topography enhance diapycnal nitrate fluxes in the upper ocean. We measured an order of magnitude increase in diapycnal nitrate fluxes to the deep chlorophyll maximum (DCM) over the Mid-Atlantic Ridge compared to the adjacent deep ocean. Internal tides drive this enhancement, with diapycnal nitrate supply to the DCM increasing by a factor of 8 between neap and spring tides. Using a global tidal dissipation database, we find that this spring-neap enhancement in diapycnal nitrate fluxes is widespread over ridges and seamounts. Mid-ocean ridges therefore play an important role in sustaining the nutrient supply to the DCM, and these findings may have important implications in a warming global ocean. Plain Language Summary The subtropical gyres cover an extensive area of the global ocean and account for similar to 30% of carbon export to the deep ocean. The pattern of the winds induces downwelling in these gyres and leads to surface waters being relatively nutrient impoverished. Biological production in the subtropical gyres is primarily limited by the availability of nitrate, which can be increased through mixing in the underlying thermocline. Internal tides can enhance mixing in the ocean interior close to steep sloping topography; deep in the ocean interior, this mixing is a key component of ocean physics. In our field study, we reveal the mixing extending up toward the surface and measured a tenfold increase in nitrate fluxes to phytoplankton in the surface ocean over the Mid-Atlantic Ridge compared to in the surface waters in the adjacent deeper ocean. Importantly, nitrate fluxes over the ridge varied fortnightly with an eightfold increase from neap to spring tides. These inferences of enhanced mixing and nutrient supply along ridges and seamounts are relevant for the rest of the global ocean given the ubiquitous nature of the tides. Article in Journal/Newspaper North Atlantic Archimer (Archive Institutionnelle de l'Ifremer - Institut français de recherche pour l'exploitation de la mer) Mid-Atlantic Ridge Global Biogeochemical Cycles 33 8 995 1009 |
institution |
Open Polar |
collection |
Archimer (Archive Institutionnelle de l'Ifremer - Institut français de recherche pour l'exploitation de la mer) |
op_collection_id |
ftarchimer |
language |
English |
topic |
mixing nitrate tides nutrients Atlantic gyre |
spellingShingle |
mixing nitrate tides nutrients Atlantic gyre Tuerena, Robyn E. Williams, Richard G. Mahaffey, Claire Vic, Clement Green, J. A. Mattias Naveira-garabato, Alberto Forryan, Alexander Sharples, Jonathan Internal Tides Drive Nutrient Fluxes Into the Deep Chlorophyll Maximum Over Mid-ocean Ridges |
topic_facet |
mixing nitrate tides nutrients Atlantic gyre |
description |
Diapycnal mixing of nutrients from the thermocline to the surface sunlit ocean is thought to be relatively weak in the world's subtropical gyres as energy inputs from winds are generally low. The interaction of internal tides with rough topography enhances diapycnal mixing, yet the role of tidally induced diapycnal mixing in sustaining nutrient supply to the surface subtropical ocean remains relatively unexplored. During a field campaign in the North Atlantic subtropical gyre, we tested whether tidal interactions with topography enhance diapycnal nitrate fluxes in the upper ocean. We measured an order of magnitude increase in diapycnal nitrate fluxes to the deep chlorophyll maximum (DCM) over the Mid-Atlantic Ridge compared to the adjacent deep ocean. Internal tides drive this enhancement, with diapycnal nitrate supply to the DCM increasing by a factor of 8 between neap and spring tides. Using a global tidal dissipation database, we find that this spring-neap enhancement in diapycnal nitrate fluxes is widespread over ridges and seamounts. Mid-ocean ridges therefore play an important role in sustaining the nutrient supply to the DCM, and these findings may have important implications in a warming global ocean. Plain Language Summary The subtropical gyres cover an extensive area of the global ocean and account for similar to 30% of carbon export to the deep ocean. The pattern of the winds induces downwelling in these gyres and leads to surface waters being relatively nutrient impoverished. Biological production in the subtropical gyres is primarily limited by the availability of nitrate, which can be increased through mixing in the underlying thermocline. Internal tides can enhance mixing in the ocean interior close to steep sloping topography; deep in the ocean interior, this mixing is a key component of ocean physics. In our field study, we reveal the mixing extending up toward the surface and measured a tenfold increase in nitrate fluxes to phytoplankton in the surface ocean over the Mid-Atlantic Ridge compared to in the surface waters in the adjacent deeper ocean. Importantly, nitrate fluxes over the ridge varied fortnightly with an eightfold increase from neap to spring tides. These inferences of enhanced mixing and nutrient supply along ridges and seamounts are relevant for the rest of the global ocean given the ubiquitous nature of the tides. |
format |
Article in Journal/Newspaper |
author |
Tuerena, Robyn E. Williams, Richard G. Mahaffey, Claire Vic, Clement Green, J. A. Mattias Naveira-garabato, Alberto Forryan, Alexander Sharples, Jonathan |
author_facet |
Tuerena, Robyn E. Williams, Richard G. Mahaffey, Claire Vic, Clement Green, J. A. Mattias Naveira-garabato, Alberto Forryan, Alexander Sharples, Jonathan |
author_sort |
Tuerena, Robyn E. |
title |
Internal Tides Drive Nutrient Fluxes Into the Deep Chlorophyll Maximum Over Mid-ocean Ridges |
title_short |
Internal Tides Drive Nutrient Fluxes Into the Deep Chlorophyll Maximum Over Mid-ocean Ridges |
title_full |
Internal Tides Drive Nutrient Fluxes Into the Deep Chlorophyll Maximum Over Mid-ocean Ridges |
title_fullStr |
Internal Tides Drive Nutrient Fluxes Into the Deep Chlorophyll Maximum Over Mid-ocean Ridges |
title_full_unstemmed |
Internal Tides Drive Nutrient Fluxes Into the Deep Chlorophyll Maximum Over Mid-ocean Ridges |
title_sort |
internal tides drive nutrient fluxes into the deep chlorophyll maximum over mid-ocean ridges |
publisher |
Amer Geophysical Union |
publishDate |
2019 |
url |
https://archimer.ifremer.fr/doc/00763/87475/92972.pdf https://archimer.ifremer.fr/doc/00763/87475/92973.docx https://doi.org/10.1029/2019GB006214 https://archimer.ifremer.fr/doc/00763/87475/ |
geographic |
Mid-Atlantic Ridge |
geographic_facet |
Mid-Atlantic Ridge |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
Global Biogeochemical Cycles (0886-6236) (Amer Geophysical Union), 2019-08 , Vol. 33 , N. 8 , P. 995-1009 |
op_relation |
https://archimer.ifremer.fr/doc/00763/87475/92972.pdf https://archimer.ifremer.fr/doc/00763/87475/92973.docx doi:10.1029/2019GB006214 https://archimer.ifremer.fr/doc/00763/87475/ |
op_rights |
info:eu-repo/semantics/openAccess restricted use |
op_doi |
https://doi.org/10.1029/2019GB006214 |
container_title |
Global Biogeochemical Cycles |
container_volume |
33 |
container_issue |
8 |
container_start_page |
995 |
op_container_end_page |
1009 |
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1766136790792536064 |