摘要：The flux of CO
2 between the atmosphere and the ocean is often estimated as the air–sea gas concentration difference multiplied by the gas transfer velocity (
K
660). The first order driver for
K
660 over the ocean is wind through its influence on near surface hydrodynamics. However, field observations have shown substantial variability in the wind speed dependencies of
K
660. In this study we measured
K
660 with the eddy covariance technique during a ~ 11,000 km long Southern Ocean transect. In parallel, we made a novel measurement of the gas transfer efficiency (GTE) based on partial equilibration of CO
2 using a Segmented Flow Coil Equilibrator system. GTE varied by 20% during the transect, was distinct in different water masses, and related to
K
660. At a moderate wind speed of 7 m s
−1,
K
660 associated with high GTE exceeded
K
660 with low GTE by 30% in the mean. The sensitivity of
K
660 towards GTE was stronger at lower wind speeds and weaker at higher wind speeds. Naturally-occurring organics in seawater, some of which are surface active, may be the cause of the variability in GTE and in
K
660. Neglecting these variations could result in biases in the computed air–sea CO
2 fluxes.
