The distribution of bomb-produced tritium and radiocarbon at GEOSECS station 347 in the eastern North Pacific

Following Roether et al. 1] an upwelling model has been tested to explain the distribution of bomb-produced tritium at the GEOSECS I test station off Baja, California. We have extended their treatment to include the time histories for tritium and for bomb radiocarbon now available for this station. If the CO₂ gas exchange rate at this station is similar to the ocean average value of 20 moles/m² yr, then the upwelling rate must be quite small (<3 m/yr). However, a satisfactory match to the time histories of¹⁴C and of³H is achieved only if an upwelling rate of 40 m/yr is used. In this case, however, a CO₂ exchange rate of 70 moles/m² yr would be required to match the observed surface water¹⁴C/C ratios and a tritium input 4 times the expected value would be needed. The inconsistency in the bomb¹⁴C time history obtained using the accepted CO₂ exchange rate is likely the result of horizontal effects which void the validity of one dimensional modeling in this region of the ocean.