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

Abstract

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.