Three-dimensional model calculation of ocean uptake of bomb ¹⁴C and implications for the global budget of bomb ¹⁴C

Two recent papers have suggested that there is an apparent imbalance in the global bomb ¹⁴C budget. These results are based in part on calculations made using simple one-dimensional ocean models. We recalculate the ocean inventory of bomb ¹⁴C using a three-dimensional ocean general circulation model, and find a significantly smaller inventory after about 1980 than in previous one-dimensional model estimates. Our new estimate of the ocean inventory implies that the apparent imbalance in the global budget of bomb ¹⁴C is smaller than previously thought and is not significantly different from zero. In addition, we use our three-dimensional model to obtain whole ocean inventories of bomb ¹⁴C during the Geochemical Ocean Sections Study (GEOSECS) period; these inventories can be used as benchmarks in calibrating one-dimensional ocean models.