Role of wind stress and heat fluxes in interannual-to-decadal variability of air-sea CO₂ and O₂ fluxes in the North Atlantic

A coupled ecosystem-circulation model of the North Atlantic is used to examine the individual contributions by wind stress and surface heat fluxes to naturally driven interannual-to-decadal variability of air-sea fluxes of CO2 and O2 during 1948–2002. The model results indicate that variations in O2 fluxes are mainly driven by variations in surface heat fluxes in the extratropics (15°N to 70°N), and by wind stress in the tropics (10°S to 15°N). Conversely, variations in simulated CO2 fluxes are predominantly wind-stress driven over the entire model domain (18°S to 70°N); while variability in piston velocity and surface heat fluxes is less important. The simulated uptake of O2 by the North Atlantic amounts to 70 ± 11 Tmol yr-1 to which the subpolar region (45°N to 70°N) contributes by 62 ± 10 Tmol yr-1. Whereas the subpolar North Atlantic takes up more than 2/3 of the total carbon absorbed by the North Atlantic in our model (about 0.3 Pg C yr-1), interannual variability of air-sea CO2 fluxes reaches similar values (about 0.01 Pg C yr-1 each) in the subpolar (45°N to 70°N), the subtropical (15°N to 45°N) and the equatorial (10°S to 15°N) Atlantic.