Southern Ocean controls of the vertical marine δ13C gradient – a modelling study
δ 13 C, the standardised 13C/12C ratio expressed in per mille, is a widely used ocean tracer to study changes in ocean circulation, water mass ventilation, atmospheric pCO2, and the biological carbon pump on timescales ranging from decades to tens of millions of years. δ13C data derived from ocean s...
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Online Access: | https://hdl.handle.net/1956/20500 https://doi.org/10.5194/bg-15-7205-2018 |
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ftunivbergen:oai:bora.uib.no:1956/20500 2023-05-15T17:35:48+02:00 Southern Ocean controls of the vertical marine δ13C gradient – a modelling study Morée, Anne Schwinger, Jörg Heinze, Christoph 2019-01-28T08:16:25Z application/pdf https://hdl.handle.net/1956/20500 https://doi.org/10.5194/bg-15-7205-2018 eng eng Copernicus Publications https://www.biogeosciences.net/15/7205/2018/ Universitetet i Bergen: 229771 Universitetet i Bergen: ns2980k Uni Research: 239965 urn:issn:1726-4170 urn:issn:1726-4189 https://hdl.handle.net/1956/20500 https://doi.org/10.5194/bg-15-7205-2018 cristin:1638891 Attribution CC BY http://creativecommons.org/licenses/by/4.0 Copyright 2018 The Author(s) Biogeosciences Peer reviewed Journal article 2019 ftunivbergen https://doi.org/10.5194/bg-15-7205-2018 2023-03-14T17:44:29Z δ 13 C, the standardised 13C/12C ratio expressed in per mille, is a widely used ocean tracer to study changes in ocean circulation, water mass ventilation, atmospheric pCO2, and the biological carbon pump on timescales ranging from decades to tens of millions of years. δ13C data derived from ocean sediment core analysis provide information on δ 13 C of dissolved inorganic carbon and the vertical δ13C gradient (i.e. Dδ13C) in past oceans. In order to correctly interpret δ13C and Dδ13C variations, a good under standing is needed of the influence from ocean circulation, air–sea gas exchange and biological productivity on these variations. The Southern Ocean is a key region for these processes, and we show here that Dδ13C in all ocean basins is sensitive to changes in the biogeochemical state of the Southern Ocean. We conduct a set of idealised sensitivity experiments with the ocean biogeochemistry general circulation model HAMOCC2s to explore the effect of biogeochemical state changes of the Southern and Global Ocean on atmospheric δ13C, pCO2, and marine δ13C and Dδ13C. The experiments cover changes in air–sea gas exchange rates, particulate organic carbon sinking rates, sea ice cover, and nutrient uptake efficiency in an unchanged ocean circulation field. Our experiments show that global mean Dδ13C varies by up to about ±0.35 ‰ around the pre-industrial model reference (1.2 ‰) in response to biogeochemical change. The amplitude of this sensitivity can be larger at smaller scales, as seen from a maximum sensitivity of about −0.6 ‰ on ocean basin scale. The ocean’s oldest water (North Pacific) responds most to biological changes, the young deep water (North Atlantic) responds strongly to air–sea gas exchange changes, and the vertically well-mixed water (SO) has a low or even reversed Dδ13C sensitivity compared to the other basins. This local Dδ13C sensitivity depends on the local thermodynamic dis- equilibrium and the Dδ13C sensitivity to local POC export production changes. The direction of both glacial (intensi- ... Article in Journal/Newspaper North Atlantic Sea ice Southern Ocean University of Bergen: Bergen Open Research Archive (BORA-UiB) Pacific Southern Ocean Biogeosciences 15 23 7205 7223 |
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Open Polar |
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University of Bergen: Bergen Open Research Archive (BORA-UiB) |
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ftunivbergen |
language |
English |
description |
δ 13 C, the standardised 13C/12C ratio expressed in per mille, is a widely used ocean tracer to study changes in ocean circulation, water mass ventilation, atmospheric pCO2, and the biological carbon pump on timescales ranging from decades to tens of millions of years. δ13C data derived from ocean sediment core analysis provide information on δ 13 C of dissolved inorganic carbon and the vertical δ13C gradient (i.e. Dδ13C) in past oceans. In order to correctly interpret δ13C and Dδ13C variations, a good under standing is needed of the influence from ocean circulation, air–sea gas exchange and biological productivity on these variations. The Southern Ocean is a key region for these processes, and we show here that Dδ13C in all ocean basins is sensitive to changes in the biogeochemical state of the Southern Ocean. We conduct a set of idealised sensitivity experiments with the ocean biogeochemistry general circulation model HAMOCC2s to explore the effect of biogeochemical state changes of the Southern and Global Ocean on atmospheric δ13C, pCO2, and marine δ13C and Dδ13C. The experiments cover changes in air–sea gas exchange rates, particulate organic carbon sinking rates, sea ice cover, and nutrient uptake efficiency in an unchanged ocean circulation field. Our experiments show that global mean Dδ13C varies by up to about ±0.35 ‰ around the pre-industrial model reference (1.2 ‰) in response to biogeochemical change. The amplitude of this sensitivity can be larger at smaller scales, as seen from a maximum sensitivity of about −0.6 ‰ on ocean basin scale. The ocean’s oldest water (North Pacific) responds most to biological changes, the young deep water (North Atlantic) responds strongly to air–sea gas exchange changes, and the vertically well-mixed water (SO) has a low or even reversed Dδ13C sensitivity compared to the other basins. This local Dδ13C sensitivity depends on the local thermodynamic dis- equilibrium and the Dδ13C sensitivity to local POC export production changes. The direction of both glacial (intensi- ... |
format |
Article in Journal/Newspaper |
author |
Morée, Anne Schwinger, Jörg Heinze, Christoph |
spellingShingle |
Morée, Anne Schwinger, Jörg Heinze, Christoph Southern Ocean controls of the vertical marine δ13C gradient – a modelling study |
author_facet |
Morée, Anne Schwinger, Jörg Heinze, Christoph |
author_sort |
Morée, Anne |
title |
Southern Ocean controls of the vertical marine δ13C gradient – a modelling study |
title_short |
Southern Ocean controls of the vertical marine δ13C gradient – a modelling study |
title_full |
Southern Ocean controls of the vertical marine δ13C gradient – a modelling study |
title_fullStr |
Southern Ocean controls of the vertical marine δ13C gradient – a modelling study |
title_full_unstemmed |
Southern Ocean controls of the vertical marine δ13C gradient – a modelling study |
title_sort |
southern ocean controls of the vertical marine δ13c gradient – a modelling study |
publisher |
Copernicus Publications |
publishDate |
2019 |
url |
https://hdl.handle.net/1956/20500 https://doi.org/10.5194/bg-15-7205-2018 |
geographic |
Pacific Southern Ocean |
geographic_facet |
Pacific Southern Ocean |
genre |
North Atlantic Sea ice Southern Ocean |
genre_facet |
North Atlantic Sea ice Southern Ocean |
op_source |
Biogeosciences |
op_relation |
https://www.biogeosciences.net/15/7205/2018/ Universitetet i Bergen: 229771 Universitetet i Bergen: ns2980k Uni Research: 239965 urn:issn:1726-4170 urn:issn:1726-4189 https://hdl.handle.net/1956/20500 https://doi.org/10.5194/bg-15-7205-2018 cristin:1638891 |
op_rights |
Attribution CC BY http://creativecommons.org/licenses/by/4.0 Copyright 2018 The Author(s) |
op_doi |
https://doi.org/10.5194/bg-15-7205-2018 |
container_title |
Biogeosciences |
container_volume |
15 |
container_issue |
23 |
container_start_page |
7205 |
op_container_end_page |
7223 |
_version_ |
1766135066862288896 |