EXPLORING CONTROLS ON THE MARINE BARIUM CYCLE USING A SPATIALLY RESOLVED OCEAN BIOGEOCHEMICAL MODEL

The marine barium (Ba) cycle has been linked to the carbon cycle, and thus Ba-based proxies have been used in many paleoceanographic studies to investigate carbon cycle dynamics. Interpretations of Ba proxies are complicated due to our limited knowledge of the processes that control marine Ba distribution. Thus far, the marine Ba cycle has been modeled only as a system of two well-mixed reservoirs representing the shallow and deep oceans. While box model approaches have provided valuable insight into some of the large-scale controls on the Ba cycle, they are not able to capture the spatial variability that is observed in the ocean Ba distribution. Thus, we add a marine Ba cycle to a three-dimensional ocean general circulation model, the Hamburg Oceanic Carbon Cycle Model Version 2.0 (HAMOCC 2.0). The simulated Ba distribution with HAMOCC is in general agreement with observed Ba concentrations. However, there are distinct differences in average Ba concentrations as well as distributions along equatorial belts and in the Arctic Ocean. Comparisons between data-inferred global Ba penetration flux estimates and model results also show distinct differences which may be related to Ba-flux parametrization. The model uses an exponential parameterization of the Ba penetration flux from the base of the euphotic zone into the deep ocean, which fits the observations better than a linear penetration flux.