Regional Pattern of the Ocean's Biological Pump Based on Geochemical Observations

Despite the impact of the ocean's biological pump on future atmospheric CO(2)and deep ocean O(2)concentrations, organic matter export rates are poorly known because observations are scarce and mostly short term. Thus, we rely on satellite data and models to yield export rates, yet neither approach is sufficiently validated. We present multiyear export estimates based mainly on observed O(2)and CO(2)surface layer budgets across the Pacific and North Atlantic Oceans and compare to satellite- and model-based estimates. We find that regional variability in observed export is modest (threefold) and lower than model- and satellite-based estimates (threefold to sevenfold). Neither model- nor satellite-based export reproduces the regional export trends in the Pacific. We find that winter mixed layer depth is critical in determining annual export rates in the subpolar N. Atlantic.