Knap 9416565 Although the intensity of carbon dioxide exchange between the ocean and atomsphere may be more greater in biologically rich areas of the world ocean, the role of the less productive oligotrophic central ocean waters in the global carbon dioxide cycle must be taken into account because of their geographic vastness. As part of the U.S. Joint Geochemical Ocean Flux Study (U.S. JGOFS), this study at the Bermuda Atlantic Time-series Station (BATS) will endeavor to study sea-air carbon dynamics in the oligotrophic North Atlantic. Specially, high-precision continuos time-series measurements of water column CO2 fugacity (a measure of ideal partial pressure of carbon dioxide in seawater) will be added to the measurements already being made at BATS to overdetermine (i.e., provide a check of internal consistency) the components of the carbonate system equilibrium and permit accurate calculation of carbon dioxide fluxes (air to sea and vice cersa). In so doing, the investigators expect to more accurately estimate the sea-air flux of CO2 at the BATS site and to reduce uncertainties in the role of the North Atlantic as a sink for atmospheric carbon dioxide. Through comparison with other time-series data at BATS, the investigators expect to achieve a clearer understanding of the underlying biological and physical processes impacting the dynamics of inorganic carbon in the oligotrophic North Atlantic, and by extrapolation, in other central ocean gyres.