Summertime atmospheric boundary layer gradients of O2 and CO2 over the Southern Ocean

Gradients were predominately anticorrelated, with excesses of delta(O-2/N-2) and depletions of CO2 found within the boundary layer, relative to a mean reference height of 1.7 km.

Through analysis of the molar ratio of the gradients (GR), the behavior of other trace gases measured in situ, and modeling experiments with the Community Earth System Model, we found that the main driver of gradients was air-sea exchange of O-2 and CO2 driven by biological processes, more so than solubility effects. An exception to this was in the eastern Drake Passage, where positive GRs were occasionally observed, likely due to the dominance of thermal forcing on the air-sea flux of both species.