GASEX 98

        Carbon dioxide exchange between the ocean and the air is an important component of climate dynamics, affecting such processes as photosynthesis and the absorption of anthropogenically-produced carbon dioxide. Despite these global implications, the actual kinetics of the transfer of carbon dioxide between the ocean and air remain elusive.

        Diverse mechanisms and properties control carbon dioxide flux, including temperature, wind speed, salinity, bubble entrainment and bioproductivity. Gas transfer rates also vary with sea state and surface chemical enhancement. These uncertainties and variances prevent mankind from fully understanding basic biological processes occurring at the surface of the ocean. This also limits our ability to realistically model future atmospheric carbon dioxide levels.



         To overcome such obstacles, the Air-Sea Interaction Group at the Woods Hole Oceanographic Institution recently developed and implemented new techniques to improve estimates of air-sea gas exchange. Designed with funding from the National Science Foundation, the new system directly measures the flux of carbon dioxide in the atmospheric boundary layer using the eddy correlation or direct covariance method.
        The new system was refined and successfully deployed during GasEx 98, a large-scale, multi-agency air-sea gas exchange experiment conducted in the North Atlantic sink region from May through June of 1998. At approximately 46°N latitude, 21°W longitude, atmospheric flux and air-sea gas concentration measurements were performed for more than 500 hours. Regions are called sinks when the absorption of carbon dioxide and other gases is found to be on a greater scale than in areas where gases are emitted.


        The GasEx 98 experiment included investigators from the National Oceanic and Atmospheric Administration (NOAA), the Woods Hole Oceanographic Institution (WHOI), and other agencies. Initial results show that flux estimates from the experiment compare well with previous estimates of the gas transfer velocity for winds below seven meters per second. However, the experiment also found that transfer velocities can be approximately 20 to 50 percent larger at higher wind speeds than previously thought.
        These preliminary investigations indicate that GasEx 98 was a successful cruise yielding several important breakthroughs in our understanding of air-sea carbon dioxide fluxes and biogeochemical cycles.
Data will be compared with measurements taken during the January - March GasEx 2001 cruise.
 
GasEx 98 Publications

Click here to learn more about GasEx 98

 

Woods Hole Oceanographic Institution
Please contact us with any questions or comments.

Return to Air-Sea Home Page