Counteracting contributions of the upper and lower meridional overturning limbs to the North Atlantic nutrient budgets: enhanced imbalance in 2010
Counteracting contributions of the upper and lower meridional overturning limbs to the North Atlantic nutrient budgets: enhanced imbalance in 2010
The North Atlantic Basin is a major sink for atmospheric carbon dioxide (CO
2) due in part to the extensive plankton blooms which form there supported by nutrients supplied by the three-dimensional ocean circulation. Hence, changes in ocean circulation and/or stratification may influence primary production and biological carbon export. In this study, we assess this possibility by evaluating inorganic nutrient budgets for 2004 and 2010 in the North Atlantic based on observations from the transatlantic A05-24.5°N and the Greenland-Portugal OVIDE hydrographic sections, to which we applied a box inverse model to solve the circulation and estimate the across-section nutrient transports. Full water column nutrient budgets were split into upper and lower meridional overturning circulation (MOC) limbs. According to our results, anomalous circulation in early 2010, linked to extreme negative NAO conditions, led to an enhanced northward advection of more nutrient-rich waters by the upper overturning limb, which resulted in a significant nitrate and phosphate convergence north of 24.5°N. Combined with heaving of the isopycnals, this anomalous circulation event in 2010 favored an enhancement of the nutrient consumption (5.7 ± 4.1 kmol-P s
−1) and associated biological CO
2 uptake (0.25 ± 0.18 Pg-C yr
−1, upper-bound estimate), which represents a 50% of the mean annual sea–air CO
2 flux in the region. Our results also suggest a transient state of deep silicate divergence in both years. Both results are indicative of a MOC-driven modulation of the biological carbon uptake (by the upper MOC limb) and nutrient inventories (by the lower MOC limb) in the North Atlantic.
Carbon cycle, North Atlantic, Nutrient and oxygen transports, Nutrient budgets, Nutrient cycles, Overturning circulation
Carracedo, L.I.
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Mercier, H.
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McDonagh, E.
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Rosón, G.
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Sanders, R.
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Moore, Christopher
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Torres‐Valdés, S.
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Brown, P.
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Lherminier, P.
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Pérez, F.F.
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June 2021
Carracedo, L.I.
bec89e77-2127-4792-982b-d5aaea471ccd
Mercier, H.
a41884c5-8915-45e1-b1d7-388248f69505
McDonagh, E.
d86c507f-6018-47da-882e-1192068709e0
Rosón, G.
1c377389-c80f-4b73-aa66-5f81d357abbc
Sanders, R.
a70fab9e-0090-499e-b33d-d0b2ecbef532
Moore, Christopher
7ec80b7b-bedc-4dd5-8924-0f5d01927b12
Torres‐Valdés, S.
61640a2f-880e-4da0-80ec-5a2b506f1703
Brown, P.
9c7bc04a-88f4-4561-88aa-aa2584e1958a
Lherminier, P.
8b12d5b7-94c7-494f-9b98-eeb34a03017e
Pérez, F.F.
c5a8495a-f3bb-4186-8d3e-cf4b12cd1d3a
Carracedo, L.I., Mercier, H., McDonagh, E., Rosón, G., Sanders, R., Moore, Christopher, Torres‐Valdés, S., Brown, P., Lherminier, P. and Pérez, F.F.
(2021)
Counteracting contributions of the upper and lower meridional overturning limbs to the North Atlantic nutrient budgets: enhanced imbalance in 2010.
Global Biogeochemical Cycles, 35 (6), [e2020GB006898].
(doi:10.1029/2020GB006898).
Abstract
The North Atlantic Basin is a major sink for atmospheric carbon dioxide (CO
2) due in part to the extensive plankton blooms which form there supported by nutrients supplied by the three-dimensional ocean circulation. Hence, changes in ocean circulation and/or stratification may influence primary production and biological carbon export. In this study, we assess this possibility by evaluating inorganic nutrient budgets for 2004 and 2010 in the North Atlantic based on observations from the transatlantic A05-24.5°N and the Greenland-Portugal OVIDE hydrographic sections, to which we applied a box inverse model to solve the circulation and estimate the across-section nutrient transports. Full water column nutrient budgets were split into upper and lower meridional overturning circulation (MOC) limbs. According to our results, anomalous circulation in early 2010, linked to extreme negative NAO conditions, led to an enhanced northward advection of more nutrient-rich waters by the upper overturning limb, which resulted in a significant nitrate and phosphate convergence north of 24.5°N. Combined with heaving of the isopycnals, this anomalous circulation event in 2010 favored an enhancement of the nutrient consumption (5.7 ± 4.1 kmol-P s
−1) and associated biological CO
2 uptake (0.25 ± 0.18 Pg-C yr
−1, upper-bound estimate), which represents a 50% of the mean annual sea–air CO
2 flux in the region. Our results also suggest a transient state of deep silicate divergence in both years. Both results are indicative of a MOC-driven modulation of the biological carbon uptake (by the upper MOC limb) and nutrient inventories (by the lower MOC limb) in the North Atlantic.
Text
Carracedo_etal_GBC
- Accepted Manuscript
More information
e-pub ahead of print date: 14 April 2021
Published date: June 2021
Additional Information:
Funding Information:
This study is a contribution to OVIDE (co-funded by the IFREMER, CNRS/INSU/LEFE), Blue-Action (EU Horizon 2020 grant agreement No 727852), ABC-Fluxes (NERC-funded grant No NE/M005046/1) projects, and CLASS (NERC National Capability Science Single Centre awards) programme. This study was supported by the TRIATLAS project (EU Horizon 2020 grant agreement No 817578). L. I. Carracedo supported by the University of Vigo through the Galician I2C Plan for postdoctoral research, NERC within the framework of the ABC-Fluxes Project, and IFREMER. H. Mercier was financed by CNRS; E. McDonagh and R. Sanders by NERC and NORCE; G. Ros?n by the University of Vigo; C. M. Moore and P. Brown by NERC; S.Torres-Vald?s by AWI; P. Lherminier by IFREMER; and F. F. P?rez by the BOCATS2 project (PID2019-104279GB-C21) co-funded by the Spanish Government and the FEDER, and by the COMFORT project (EU Horizon 2020 grant agreement No 820989). The authors are grateful to the captains, crew, technicians, and scientists who contributed to the acquisition, processing, and quality control of the hydrographic data used in this study. The authors particularly thank P. Zunino for her valuable contribution to the OVIDE data interpolation.
Funding Information:
This study is a contribution to OVIDE (co‐funded by the IFREMER, CNRS/INSU/LEFE), Blue‐Action (EU Horizon 2020 grant agreement No 727852), ABC‐Fluxes (NERC‐funded grant No NE/M005046/1) projects, and CLASS (NERC National Capability Science Single Centre awards) programme. This study was supported by the TRIATLAS project (EU Horizon 2020 grant agreement No 817578). L. I. Carracedo supported by the University of Vigo through the Galician I2C Plan for postdoctoral research, NERC within the framework of the ABC‐Fluxes Project, and IFREMER. H. Mercier was financed by CNRS; E. McDonagh and R. Sanders by NERC and NORCE; G. Rosón by the University of Vigo; C. M. Moore and P. Brown by NERC; S.Torres‐Valdés by AWI; P. Lherminier by IFREMER; and F. F. Pérez by the BOCATS2 project (PID2019‐104279GB‐C21) co‐funded by the Spanish Government and the FEDER, and by the COMFORT project (EU Horizon 2020 grant agreement No 820989). The authors are grateful to the captains, crew, technicians, and scientists who contributed to the acquisition, processing, and quality control of the hydrographic data used in this study. The authors particularly thank P. Zunino for her valuable contribution to the OVIDE data interpolation.
Publisher Copyright:
© 2021. The Authors.
Keywords:
Carbon cycle, North Atlantic, Nutrient and oxygen transports, Nutrient budgets, Nutrient cycles, Overturning circulation
Identifiers
Local EPrints ID: 449171
URI: http://eprints.soton.ac.uk/id/eprint/449171
ISSN: 0886-6236
PURE UUID: 8a4a6882-3adf-4254-95a4-8d1b677f6421
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Date deposited: 18 May 2021 16:33
Last modified: 17 Mar 2024 02:49
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Contributors
Author:
L.I. Carracedo
Author:
H. Mercier
Author:
E. McDonagh
Author:
G. Rosón
Author:
R. Sanders
Author:
S. Torres‐Valdés
Author:
P. Brown
Author:
P. Lherminier
Author:
F.F. Pérez
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