This physical-biological modeling study of the interactions that control the exchange of carbon dioxide between the ocean and the atmosphere in the Southern Ocean is a joint effort between Columbia University and the University of Southern California. This component of the project concerns the physical and chemical processes in the ocean that determine the fluxes of carbon dioxide. The Southern Ocean is of particular importance in this context because it represents one of the two global regions where deep convection allows the ventilation of upwelling water masses, and where the sinking of surface waters removes unutilized nutrients from the euphotic zone. This area has a large range of physical, chemical, and biological processes, so that the seasonal amplitude of the carbon dioxide flux is also large, and makes individual observations poor estimators of the annual mean value. In fact it is currently not clear whether this region is one of net uptake or release of carbon dioxide to the atmosphere. An existing one-dimensional model which describes the vertical air/sea/ice interactions and energy fluxes will be modified to include the effects of air-sea gas exchange and the relevant chemistry and carbon flow within the planktonic communities of the upper ocean. A series of experiments will be performed to determine the sensitivity of the model to parameterization schemes, initial conditions, and boundary conditions. Ultimately the model will be coupled to a global circulation model developed by the Goddard Institute of Space Studies in order to answer such specific questions as what are the factors that determine the general patterns of horizontal phytoplankton distribution as observed by satellite-based color scanners; what is the relationship between pigment distributions and rates of primary productivity; what fraction is new production exportable to the deep ocean, and what is the magnitude of the biogenic flux of carbon dioxide in the deep Southern Ocean.
