Southwest Subtropical Pacific Surface Water Radiocarbon in a High-resolution Coral Record

We have generated a high-resolution coral D14C record from the southwest subtropical Pacific spanning the last 50 yr. Prebomb (1950–1956) D14C values average -52‰. 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‰ 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.