Community Research and Development Information Service - CORDIS


PASSME Report Summary

Project ID: 336408
Funded under: FP7-IDEAS-ERC
Country: Germany

Mid-Term Report Summary - PASSME (Air-sea gas exchange - PArameterization of the Sea-Surface Microlayer Effect)

Our project aims a better understanding of the exchange of carbon dioxide (CO2) between the ocean and atmosphere with a special focus on interfacial processes at the sea surface. A better understanding in the oceanic uptake of atmospheric CO2 is critical in predicting climate trends and establishing policies.
First, our work focused on the development of new technologies to measure the exchange of CO2 across the sea surface and mapping the sea surface on biochemical parameters. We designed an autonomous buoy to monitor CO2 air-sea fluxes with high temporal resolution to advance our understanding how fast-changing meteorological conditions influence gas exchange. To monitor biological and chemical properties of the sea surface, as well meteorological forcing, we developed a remote controlled catamaran skimming thin layers from the sea surface for in situ measurements. Through the technological developments, the group can apply the novel approach to investigate the effect of the sea surface on air-sea gas exchange. Secondly, with the completion of three expeditions we have created a database currently containing 200 air-sea CO2 fluxes and half a million data points to assess properties of the sea surface. We have been able to confirm the hypothesis that the accumulation of natural surfactants at the sea surface cannot be neglected in the assessment of gas exchange processes. Our database will also allow us to refine equations for the assessment of gas transfer solely based on the wind speed. The equations are poorly characterized, especially in the lower range of wind speeds. For this purpose, we assessed air-sea gas exchange under controlled wind speeds in a large annular wind-wave tunnel. Thirdly, our microbiological studies revealed that the sea surface holds also a distinct microbial community forming under certain conditions biofilm-like habitats influencing the exchange of CO2 between the ocean and atmosphere.
Overall, our new approach studying air-sea gas exchange allows us to create a valuable database to refine equations to assess air-sea exchange of climate-relevant gases on a global scale.

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