Southwest subtropical pacific surface water radiocarbon in a high-resolution coral record

We have generated a high-resolution coral Delta C-14 record from the southwest subtropical Pacific spanning the last 50 yr. Prebomb (1950-1956) Delta C-14 values average -52 parts per thousand. Values begin to increase in 1957, reaching a maximum in the early 1970s, about 10 yr after the atmospheric peak. There is a consistent 10-15 parts per thousand seasonal cycle whose relationship with vertical mixing evolves as a consequence of the penetration of the bomb transient into subsurface waters. Comparison of this record with that simulated in an ocean general circulation model highlights the difficulty in modeling vertical exchange processes.