The sea surface CO₂ fugacity and its relationship with environmental parameters in the subpolar North Atlantic 2005

A. Olsen (1, 2, 3) , K. R. Brown (1) , M. Chierici (3) , T. Johannessen (1, 2) , C. Neill (1)

1 BCCR - Bjerknes Centre for Climate Research
2 GFI / BiU - Geophysical Institute [Bergen]
3 Marine Chemistry

We present the first year-long subpolar transatlantic set of surface seawater CO₂ fugacity (fCO₂^sw) data. The data were obtained aboard the MV Nuka Arctica in 2005 and provide a quasi-continuous picture of the fCO₂^sw variability between Denmark and Greenland. Complementary real-time high resolution data of surface chlorophyll a (chl a) concentrations and mixed layer depth (MLD) estimates have been collocated with the fCO₂^sw data. Off the shelves the fCO₂^sw goes through a pronounced seasonal cycle. Surface waters are saturated to slightly supersaturated over a wide range of temperatures in winter. Through spring and summer fCO₂^sw decreases by approximately 60 ?atm due to biological carbon consumption which is not fully counteracted by the fCO₂^sw increase due to summer warming. The changes are synchronous with changes in chl a concentrations and MLD, and fCO₂^sw is correlated to both of these through exponential decay and growth curves, respectively. In particular, MLD appears to be able to predict open ocean subpolar fCO₂^sw to within 12 ?atm using a single equation for the whole year. The predictive capability of chl a is around 20% less, with root mean square values of 14.5 ?atm. As fCO₂^sw extrapolation parameters, both MLD and chl a outperform sea surface temperatures in the open subpolar North Atlantic. However, the situation on the shelves is much more heterogeneous and the fCO₂^sw?parameter relationships are not as strong as they are off the shelves.

Domaines: Cosmologie et astrophysique extra-galactique [astro-ph.CO]; Astrophysique [astro-ph]; Interfaces continentales, environnement; Océan, Atmosphère; Sciences de la Terre

A. Olsen, K. R. Brown, M. Chierici, T. Johannessen, C. Neill. The sea surface CO₂ fugacity and its relationship with environmental parameters in the subpolar North Atlantic 2005. Biogeosciences Discussions, 2007, 4 (3), pp.1737-1777. ⟨hal-00297897⟩