Subproject 4.3: Determination of the transfer velocity by a combined CO2/O2 surface water budget

 

Bernd Schneider, Robert Schmidt

Continuous measurements of the partial pressure of CO₂ and O₂ are used to calculate temporal changes of the total CO₂ (C_T) and of the O₂ concentrations in the surface water. A budget for both CO₂ and O₂ will be established for time intervals of days to weeks resulting in two independent mass balance equations. These allow the determination of the mean transfer velocity, since at stable surface water stratification the major sink/source terms for CO₂ and O₂ are the air-sea flux and the biological production. These measurements are performed on the cargo ship FINNMAID and on the research platform FINO2. The mean transfer velocities will be used to validate parameterizations evolving from the high resolution flux determinations by eddy covariance and by thermography.
Furthermore, measurements of the surface tension (σ) will be used to characterize the surface film coverage at different seasons corresponding to the state of biological production. The data will be related to both the eddy covariance and the budget derived flux data in order to estimate a “film factor” that may be included in any parameterization of the transfer velocity.