Quantifying the surface physical controls on CO2 transfer during the Southern Ocean Gas Exchange Experiment

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The problem of quantifying the rate of gas flux across the air-water interface is one of the central questions of oceanography and is critical in the context of greenhouse gases and ocean-atmosphere budgets. The large uncertainty surrounding the flux of CO2 between the atmosphere and ocean prevent us from determining the partitioning of the sink of anthropogenic CO2 between the ocean and the terrestrial biosphere. This uncertainty also limits our ability to realistically model future atmospheric CO2 levels. The International SOLAS (Surface Ocean ? Lower Atmosphere Study) science plan and implementation strategy highlights the need for an improved understanding of gas exchange. As stated in the plan ?The objective of [SOLAS] focus 2 is to develop quantitative understanding of processes responsible for air-sea exchange of mass, momentum and energy to permit accurate calculation of regional and global gas and aerosol fluxes. This requires establishing the dependence of these interfacial transfer mechanisms on physical, biological and chemical factors within the atmospheric and oceanic boundary layers...? In this project, researchers at the University of Miami's Rosenstiel School for Marine and Atmospheric Science will make a unique set of measurements of sea-air CO2 exchange measurements in the Southern Ocean as part of the forthcoming ?Southern Ocean Gas Exchange? (SOGasEx) experiment. SOGasEx (also known as GasEx III) is designed to carry out these measurements, and to determine the factors controlling air-sea gas exchange at high winds. The Miami research team expect to enhance the primarily ship-based SOGasex measurements with their unique capabilities to make high resolution measurements of the air-sea interface from autonomous platforms. Specifically they will deploy a new Extreme Air-Sea Interaction (EASI) buoy to measure direct fluxes of CO2, aerosol, sensible and latent heat, and momentum, as well as basic meteorological and oceanic parameters (wind speed, stability, air temperature, humidity, SST, etc), as well as an Air-Sea Interaction Spar (ASIS) buoy to measure the controlling surface physical processes (surface waves including slopes, currents, upper ocean turbulence and mixing). Many of these measurements cannot be made from a ship in a high wave environment due to flow distortion, etc, -- hence the need for autonomous platforms. In addition, they will measure white cap coverage using a camera/video system mounted on the ship. With these measurements, we hope to advance our understanding of gas transfer process related specifically to high wind processes.In terms of broader impacts, this work relates to improvement of our ability to predict atmospheric CO2 levels and to assess how they might change climate under various scenarios. Climate change is emerging as one of the most challenging policy issues faced by governments. Our current lack of an adequate parameterization of air-sea gas transfer rates contributes directly to our inability to predict with certainty future concentrations of CO2 and other climate relevant compounds in the atmosphere. This study is expected to improve the accuracy of global ocean carbon dioxide flux estimates and increase our understanding of the causes of its variability. The proposed measurements employ state-of-the-art instrumentation, which will enhance the SOGasEx experiment. The opportunity to participate in this experiment, and access to the data for subsequent analysis will provide for a unique dataset with which to increase our understanding of the role of air-sea CO2 exchange in influencing climate.