FN Archimer Export Format
PT J
TI Ocean carbonate system variability in the North Atlantic Subpolar surface water (1993–2017)
BT 
AF Leseurre, Coraline
   Lo Monaco, Claire
   Reverdin, Gilles
   Metzl, Nicolas
   Fin, Jonathan
   Olafsdottir, Solveig
   Racapé, Virginie
AS 1:1;2:1;3:1;4:1;5:1;6:2;7:3;
FF 1:;2:;3:;4:;5:;6:;7:PDG-ODE-LOPS;
C1 Laboratoire d'Océanographie et du Climat: Expérimentation et Approches Numériques (LOCEAN-IPSL), Sorbonne Université-CNRS-IRD-MNHN, Paris, 75005, France
   Marine and Freshwater Research Institute (MFRI), Reykjavík, Iceland
   Laboratoire d'Océanographie Physique et Spatiale (LOPS), CNRS-IFREMER-IRD-UBO, Plouzané, 29280, France
C2 CNRS, FRANCE
   MFRI, ICELAND
   IFREMER, FRANCE
SI BREST
SE PDG-ODE-LOPS
UM LOPS
IN WOS Ifremer UMR
   DOAJ
   copubli-france
   copubli-europe
IF 4.295
TC 11
UR https://archimer.ifremer.fr/doc/00631/74356/74023.pdf
   https://archimer.ifremer.fr/doc/00631/74356/74024.pdf
   https://archimer.ifremer.fr/doc/00631/74356/74025.pdf
LA English
DT Article
CR OVIDE
   SURATLANT
AB The North Atlantic is one of the major ocean sinks for natural and anthropogenic atmospheric CO2. Given the variability of the circulation, convective processes or warming–cooling recognized in the high latitudes in this region, a better understanding of the CO2 sink temporal variability and associated acidification needs a close inspection of seasonal, interannual to multidecadal observations. In this study, we investigate the evolution of CO2 uptake and ocean acidification in the North Atlantic Subpolar Gyre (50–64∘ N) using repeated observations collected over the last 3 decades in the framework of the long-term monitoring program SURATLANT (SURveillance de l'ATLANTique). Over the full period (1993–2017) pH decreases (−0.0017 yr−1) and fugacity of CO2 (fCO2) increases (+1.70 µatm yr−1). The trend of fCO2 in surface water is slightly less than the atmospheric rate (+1.96 µatm yr−1). This is mainly due to dissolved inorganic carbon (DIC) increase associated with the anthropogenic signal. However, over shorter periods (4–10 years) and depending on the season, we detect significant variability investigated in more detail in this study. Data obtained between 1993 and 1997 suggest a rapid increase in fCO2 in summer (up to +14 µatm yr−1) that was driven by a significant warming and an increase in DIC for a short period. Similar fCO2 trends are observed between 2001 and 2007 during both summer and winter, but, without significant warming detected, these trends are mainly explained by an increase in DIC and a decrease in alkalinity. This also leads to a pH decrease but with contrasting trends depending on the region and season (between −0.006 and −0.013 yr−1). Conversely, data obtained during the last decade (2008–2017) in summer show a cooling of surface waters and an increase in alkalinity, leading to a strong decrease in surface fCO2 (between −4.4 and −2.3 µatm yr−1; i.e., the ocean CO2 sink increases). Surprisingly, during summer, pH increases up to +0.0052 yr−1 in the southern subpolar gyre. Overall, our results show that, in addition to the accumulation of anthropogenic CO2, the temporal changes in the uptake of CO2 and ocean acidification in the North Atlantic Subpolar Gyre present significant multiannual variability, not clearly directly associated with the North Atlantic Oscillation (NAO). With such variability it is uncertain to predict the near-future evolution of air–sea CO2 fluxes and pH in this region. Thus, it is highly recommended to maintain long-term observations to monitor these properties in the next decade. 
PY 2020
PD MAY
SO Biogeosciences
SN 1726-4170
PU Copernicus GmbH
VL 17
IS 9
UT 000535232300001
BP 2553
EP 2577
DI 10.5194/bg-17-2553-2020
ID 74356
ER

EF