Ventilation of the deep ocean constrained with tracer observations and implications for radiocarbon estimates of ideal mean age
Ocean ventilation is the process that transports water and climatically important trace gases such as carbon dioxide from the surface mixed layer into the ocean interior. Quantifying the dominant source regions and time scales remains a major challenge in oceanography. A mathematically rigorous appr...
Published in: | Earth and Planetary Science Letters |
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Language: | English |
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Online Access: | https://doi.org/10.1016/j.epsl.2012.01.038 https://ora.ox.ac.uk/objects/uuid:47ab5191-0837-434b-b273-b1f1382b4245 |
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ftuloxford:oai:ora.ox.ac.uk:uuid:47ab5191-0837-434b-b273-b1f1382b4245 2023-05-15T17:32:02+02:00 Ventilation of the deep ocean constrained with tracer observations and implications for radiocarbon estimates of ideal mean age Khatiwala, S Primeau, F Holzer, M 2016-07-28 https://doi.org/10.1016/j.epsl.2012.01.038 https://ora.ox.ac.uk/objects/uuid:47ab5191-0837-434b-b273-b1f1382b4245 eng eng doi:10.1016/j.epsl.2012.01.038 https://ora.ox.ac.uk/objects/uuid:47ab5191-0837-434b-b273-b1f1382b4245 https://doi.org/10.1016/j.epsl.2012.01.038 info:eu-repo/semantics/embargoedAccess Journal article 2016 ftuloxford https://doi.org/10.1016/j.epsl.2012.01.038 2022-06-28T20:11:17Z Ocean ventilation is the process that transports water and climatically important trace gases such as carbon dioxide from the surface mixed layer into the ocean interior. Quantifying the dominant source regions and time scales remains a major challenge in oceanography. A mathematically rigorous approach, that accounts for the multiplicity of transport pathways and transit times characteristic of an eddy-diffusive flow such as the ocean, is to quantify ventilation in terms of a probability distribution that partitions fluid parcels according to the time and location of their last surface contact. Here, we use globally gridded radiocarbon data in combination with other transient (CFCs) and hydrographic (temperature, salinity, phosphate, and oxygen) tracer data to estimate the joint distribution of age and surface origin of deep ocean waters. Our results show that ~. 40% and 26% of the global ocean was last in contact with the Southern Ocean and North Atlantic, respectively. Some 80% of the global deep ocean below 1500. m is ventilated from these high latitude regions. However, contrary to the classical description of the deep ocean as a roughly equal mixture of "northern" and "southern" source waters, we find a significantly higher contribution from the Southern Ocean relative to the North Atlantic. We estimate the mean transit time from the surface to the deep North Pacific at 1360±350. y, intermediate between two widely used radiocarbon-based estimates. To reconcile our estimate of the ideal mean age with ventilation age estimates based on radiocarbon, we apply the estimated distribution function to construct a 3-dimensional distribution of the water mass fraction-weighted surface "initial" radiocarbon concentration that can serve as an accurate reservoir age. Radiocarbon ages corrected for this initial reservoir age are found to be in good agreement (within 5%) with our ideal age estimate, demonstrating that it is essential to take into account the spatially variable surface radiocarbon field when computing ... Article in Journal/Newspaper North Atlantic Southern Ocean ORA - Oxford University Research Archive Pacific Southern Ocean Earth and Planetary Science Letters 325-326 116 125 |
institution |
Open Polar |
collection |
ORA - Oxford University Research Archive |
op_collection_id |
ftuloxford |
language |
English |
description |
Ocean ventilation is the process that transports water and climatically important trace gases such as carbon dioxide from the surface mixed layer into the ocean interior. Quantifying the dominant source regions and time scales remains a major challenge in oceanography. A mathematically rigorous approach, that accounts for the multiplicity of transport pathways and transit times characteristic of an eddy-diffusive flow such as the ocean, is to quantify ventilation in terms of a probability distribution that partitions fluid parcels according to the time and location of their last surface contact. Here, we use globally gridded radiocarbon data in combination with other transient (CFCs) and hydrographic (temperature, salinity, phosphate, and oxygen) tracer data to estimate the joint distribution of age and surface origin of deep ocean waters. Our results show that ~. 40% and 26% of the global ocean was last in contact with the Southern Ocean and North Atlantic, respectively. Some 80% of the global deep ocean below 1500. m is ventilated from these high latitude regions. However, contrary to the classical description of the deep ocean as a roughly equal mixture of "northern" and "southern" source waters, we find a significantly higher contribution from the Southern Ocean relative to the North Atlantic. We estimate the mean transit time from the surface to the deep North Pacific at 1360±350. y, intermediate between two widely used radiocarbon-based estimates. To reconcile our estimate of the ideal mean age with ventilation age estimates based on radiocarbon, we apply the estimated distribution function to construct a 3-dimensional distribution of the water mass fraction-weighted surface "initial" radiocarbon concentration that can serve as an accurate reservoir age. Radiocarbon ages corrected for this initial reservoir age are found to be in good agreement (within 5%) with our ideal age estimate, demonstrating that it is essential to take into account the spatially variable surface radiocarbon field when computing ... |
format |
Article in Journal/Newspaper |
author |
Khatiwala, S Primeau, F Holzer, M |
spellingShingle |
Khatiwala, S Primeau, F Holzer, M Ventilation of the deep ocean constrained with tracer observations and implications for radiocarbon estimates of ideal mean age |
author_facet |
Khatiwala, S Primeau, F Holzer, M |
author_sort |
Khatiwala, S |
title |
Ventilation of the deep ocean constrained with tracer observations and implications for radiocarbon estimates of ideal mean age |
title_short |
Ventilation of the deep ocean constrained with tracer observations and implications for radiocarbon estimates of ideal mean age |
title_full |
Ventilation of the deep ocean constrained with tracer observations and implications for radiocarbon estimates of ideal mean age |
title_fullStr |
Ventilation of the deep ocean constrained with tracer observations and implications for radiocarbon estimates of ideal mean age |
title_full_unstemmed |
Ventilation of the deep ocean constrained with tracer observations and implications for radiocarbon estimates of ideal mean age |
title_sort |
ventilation of the deep ocean constrained with tracer observations and implications for radiocarbon estimates of ideal mean age |
publishDate |
2016 |
url |
https://doi.org/10.1016/j.epsl.2012.01.038 https://ora.ox.ac.uk/objects/uuid:47ab5191-0837-434b-b273-b1f1382b4245 |
geographic |
Pacific Southern Ocean |
geographic_facet |
Pacific Southern Ocean |
genre |
North Atlantic Southern Ocean |
genre_facet |
North Atlantic Southern Ocean |
op_relation |
doi:10.1016/j.epsl.2012.01.038 https://ora.ox.ac.uk/objects/uuid:47ab5191-0837-434b-b273-b1f1382b4245 https://doi.org/10.1016/j.epsl.2012.01.038 |
op_rights |
info:eu-repo/semantics/embargoedAccess |
op_doi |
https://doi.org/10.1016/j.epsl.2012.01.038 |
container_title |
Earth and Planetary Science Letters |
container_volume |
325-326 |
container_start_page |
116 |
op_container_end_page |
125 |
_version_ |
1766129939022610432 |