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Postdoctoral Research Position
in Physical Oceanography at LOPS – Ifremer

'Physical mechanisms involved in deep CO₂ storage variability in the North-Atlantic'

We seek a physical oceanographer to join the Laboratoire d’Océanographie Physique et Spatiale, Ifremer in Brest (France) to investigate the key physical drivers of carbon uptake and storage in the subpolar gyre of the North Atlantic and to provide climate indicators on the capacity of the subpolar gyre at storing carbon. The research will be mainly based on the analysis of in situ data from the Argo program (standard, deep and BGC), complemented by other in situ observations like the OVIDE dataset.

The work will be carried out as part of EUROSEA (European Contribution to the Future of the Seas and Oceans Flagship Initiative) Project - WP7 Climate Demonstration, Task 7.1: Carbon and heat uptake in the Subpolar NW Atlantic.

Location: Laboratoire d’Océanographie Physique et Spatiale, Ifremer (Brest, France)
Contract: 18 months 

Deadline for application: September 1st, 2021

How to apply: Please send your detailed CV including a list of publications, cover letter, and name/email of at least 2 references to V. Thierry ( and L. Carracedo (



Counteracting Contributions of the Upper and Lower Meridional Overturning Limbs to the North Atlantic Nutrient Budgets: Enhanced Imbalance in 2010

Published in Global Biogeochemical Cycles

April 2021

The North Atlantic Basin is a major sink for atmospheric  carbon dioxide (CO₂) 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 assessed 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.

Key Points:
• The overturning circulation lower limb drives a net southward transport of oxygen and nutrients from the North to the South Atlantic
• Anomalous circulation in 2010 enhanced nutrient convergence by the overturning upper limb, boosting North Atlantic biological CO₂ uptake
• We observed a deep silicate divergence in the North Atlantic in 2004 and 2010 compatible with a transient response to reduced overturning

Citation: Carracedo, L. I., Mercier, H., McDonagh, E., Rosón, G., Sanders, R., Moore, C. M., et al. (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, e2020GB006898. https://doi. org/10.1029/2020GB006898



The BOCATS2 2021 cruise took place in
May-Jun 2021 along the Portugal to
Greendland OVIDE section. BOCATS2
2021 and 2023 cruises continue the occupation
of the A25-OVIDE biennial section, part of the
international GO-SHIP programme.


The accumulation of anthropogenic carbon (Cant) in the North Atlantic is strongly linked to the Meridional Overturning Circulation (MOC) (ref. 1), which is highly variable and predicted to decline during the 21st century as the Earth warms (ref. 2). At 26°N, the upstream extension of the Gulf Stream, namely the Florida Current (FC), is confined to a very narrow passage of about 90 km and 800 m depth off the east coast of Florida (Florida Straits). This very intense current (~32 Sv, ref. 3) comprises the bulk of the Cant-loaded upper northward limb of MOC (refs. 1, 4). Hence, gaining a better understanding of the magnitude, variability, and likely future trends in North Atlantic carbon accumulation in response to changing upper MOC, that is, changes in volume, heat, carbon and nutrient transports as observed across the Florida Straits, is crucial for determining the fate of global carbon stocks and the impacts on North Atlantic ecosystems.

Within this context, the CANAIMOC Workshop* aimed to favour discussion and exchange of ideas on the study of the role of the Gulf Stream on the carbon cycle in the North Atlantic.

The CANAIMOC Workshop (February 2021) consisted of three separate events:

# 1-day Educational Seminar Session (with students), 17 Feb

# 2-day Science Seminar Session (open to scientific community), 23-24 Feb

# 1-day Project Discussion Session (with collaborators): 25 Feb

(*) This workshop was supported by LOPS (Laboratory for Ocean Physics and Satellite remote sensing) and ISblue project, Interdisciplinary graduate school for the blue planet (ANR-17-EURE-0015) and co-funded by a grant from the French government under the program "Investissements d'Avenir".

1 Pérez, F. F. et al. Atlantic Ocean CO₂ uptake reduced by weakening of the meridional overturning circulation. Nature  Geoscience 6, 146–152 (2013);
2 IPCC, 2019: IPCC Special Report on the Ocean and Cryosphere in a Changing Climate [H.-O. Pörtner, D.C. Roberts, V. Masson-Delmotte, P. Zhai, M. Tignor, E. Poloczanska, K. Mintenbeck, A. Alegría, M. Nicolai, A. Okem, J. Petzold, B. Rama, N.M. Weyer (eds.)]. In press;
3 Baringer, M. O. & Larsen, J. C. Sixteen years of Florida Current Transport at 27° N. Geophys. Res. Lett. 28, 3179–3182 (2001);
4 Meinen, C. S., Baringer, M. O. & Garcia, R. F.Florida Current transport variability: An analysis of annual and longer-period signals. Deep Sea Research Part I: Oceanographic Research Papers 57, 835–846 (2010). 

                    CANAIMOC Virtual Workshop - Science Seminar Session Program


Session 1: AMOC variability

Tue 23th Feb, 1500-1640 (CET)

Chair: L. Carracedo (LOPS, Ifremer, France) 

15:00 – 15.10     Welcome and overview Seminar Session 1.
15.10 – 15:25     AMOC across the OVIDE section. H. Mercier (LOPS, CNRS, France)
15:25 – 15:40    AMOC across RAPID section. E. Frajka-Williams (NOC, UK)
15:40 – 15:55    AMOC mechanisms. S. Lozier (Georgia Tech, Earth and Atmospheric Sciences, USA)
15:55 – 16:10     Latitudinal shift of the AMOC source regions. C. Lique (LOPS, Ifremer, France)
16:10 – 16:25     Mechanisms of ocean heat content variability. D. Desbruyères (LOPS, Ifremer, France)
16:25 – 16:40    Q&A.  Closing up Science Seminar Session 1.


Session 2: Feedbacks between the AMOC and ocean carbon cycle

Tue 23th Feb, 1640-1800 (CET)

Chair: M. Garcia-Ibáñez (UEA, UK) 

16:40 – 16:45    Overview Seminar Session 2.
16:45 – 17:00    Cant and excess ocean heat content in the Subtropical NA Ocean. M.J. Messias (Uni of Exeter, UK)
17:00 – 17:15     Cant in the subpolar gyre. F. F. Pérez (IIM-CSIC, Spain)
17:15 – 17:30     Cant transport across RAPID. P. Brown (NOC, UK)
17:30 – 17:45     MOC regulation of nutrient inventories in the North Atlantic. L. Carracedo (LOPS, Ifremer, France)
17:45 – 18:00    Q&A. Closing up Science Seminar Session 2. 


Session 3: The Florida Current/Gulf Stream as an anthropogenic carbon and nutrient stream 

Wed 24th Feb 2021, 1430-1800 (CET)

Chair: P. Lherminier (LOPS, Ifremer, France) 

14:30 – 14:40    Welcome and overview Seminar Session 3.
14:40 – 14:55    Florida Current variability. D. Volkov (AOML, NOAA, USA)
14:55 – 15:10    Likely weakening of the Florida Current during the past century. C. Piecuch (WHOI, USA)
15:10 – 15:25    Freshwater/heat transport across the Florida Strait. E. McDonagh (NORCE, Norway)
15:30 – 15:45    DIC transport across the Florida Strait. N. Bates (BIOS, Bermuda)
15:45 – 16:00    DIC transport and coastal acidification off the east coast of Florida. Y. Xu (AOML, NOAA, USA)
16:00 – 16:15    Surface OA in the Northern Caribbean Sea, including the FC. R. Wanninkhof (AOML, NOAA, USA)
16:15 – 16:30    Ocean carbon uptake in the Gulf Stream and STMW region. J. Palter (Uni of Rhode Island, USA)

16:35 – 16:50    The North Atlantic nutrient stream. R. Williams (Uni of Liverpool, UK)
16:50 – 17:05    N₂ fixation in the Gulf Stream. M. Benavides (MIO, France)
17:05 – 17:20    Diapycnal nutrient fluxes to the euphotic zone in the Florida Straits. J.Z. Zhang (AOML, NOAA, USA)
17:20 – 17:35    Nutrient variability across Florida Straits. L. Carracedo (LOPS, Ifremer, France)
17:35 – 17:50    Pursuing new measures of change in the Florida Straits, L. Beal & H. Close (RSMAS, Uni of Miami, USA)
17:50 – 18:00   Q&A. Closing up Science Seminar Session.