Natascha Kljun

In Arctic fjords and high‐latitude seas, strong surface cooling dominates during a large part of the year, generating water‐side convection (w* w) and enhanced turbulence in the water. These regions are key areas for the global carbon cycle; thus, a correct description of their air‐sea gas exchange is crucial. CO2 data were measured via the eddy covariance technique in marine Arctic conditions and reveal that water‐side convection has a major impact on the gas transfer velocity. This is observed even at wind speeds as high as 9 m s−1, where convective motions are generally thought to be suppressed by wind‐driven turbulence. The enhanced air‐sea transfer of CO2 caused by water‐side convection nearly doubled the CO2 uptake; after scaled to open‐sea conditions the contribution from w* w to the CO2 flux remained as high as 34%. This phenomenon is expected to be highly important for the total carbon uptake in marine Arctic areas.