Wintertime fCO₂ variability in the Subpolar North Atlantic since 2004

Friederike Fröb (1, 2) , Are Olsen (1, 2) , Meike Becker (1, 2) , Léon Chafik (1, 2) , Truls Johannessen (2, 1) , Gilles Reverdin (3) , Abdirahman M. Omar (1)

1 BCCR - Bjerknes Centre for Climate Research
2 GFI / BiU - Geophysical Institute [Bergen]
3 PROTEO - Processus et interactions de fine échelle océanique

Winter data of surface ocean temperature (SST), salinity (SSS) and CO$_2$ fugacity (fCO$_2$) collected on the VOS M/V Nuka Arctica in the subpolar North Atlantic between 2004 and 2017 are used to establish trends, drivers, and interannual variability. Over the period, waters cooled and freshened, and the fCO$_2$ increased at a rate similar to the atmospheric CO$_2$ growth rate. When accounting for the freshening, the inferred increase in dissolved inorganic carbon (DIC) was found to be approximately twice that expected from atmospheric CO$_2$ alone. This is attributed to the cooling. In the Irminger Sea, fCO$_2$ exhibited additional interannual variations driven by atmospheric forcing through winter mixing. As winter fCO$_2$ in the region is close to the atmospheric, the subpolar North Atlantic has varied between being slightly supersaturated and slightly undersaturated over the investigated period.

Domaines: Géophysique [physics.geo-ph]; Planète et Univers [physics]

Friederike Fröb, Are Olsen, Meike Becker, Léon Chafik, Truls Johannessen, et al.. Wintertime fCO₂ variability in the Subpolar North Atlantic since 2004. Geophysical Research Letters, 2019, 46 (3), pp.1580-1590. ⟨10.1029/2018GL080554⟩. ⟨hal-02193209⟩