COsub2/sub-flux measurements above the Baltic Sea at two heights: flux gradients in the surface layer?

摘要

The estimation of CO₂ exchange between the ocean and the atmosphere is essential tounderstand the global carbon cycle. The eddy-covariance technique offers a very direct approach to observe thesefluxes. The turbulent CO₂ flux is measured, as well as the sensible and latent heat flux and themomentum flux, a few meters above the ocean in the atmosphere.Assuming a constant-flux layer in the near-surface part of the atmospheric boundary layer, this flux equalsthe exchange flux between ocean and atmosphere. The purpose of this paper is the comparison of long-termflux measurements at two different heights above the Baltic Sea to investigate this assumption. Theresults are based on a 1.5-year record of quality-controlled eddy-covariance measurements.Concerning the flux of momentum and of sensible and latent heat, the constant-flux layer theory canbe confirmed because flux differences between the two heights are insignificantly small more than 95 % of the time. In contrast, significant differences, which are larger than the measurementerror, occur in the CO₂ flux about 35 % of the time. Data used for this paper arepublished at href="http://doi.pangaea.de/10.1594/PANGAEA.808714" target="_blank">http://doi.pangaea.de/10.1594/PANGAEA.808714.