HR: 11:20h
AN: OS31D-05    [PDF]
TI: Surface Water Processes in the Indonesian Throughflow as Documented by a 115-Year High-Resolution Coral $\Delta$$^{14}$C Record
AU: * Fallon, S J
EM: Fallon4@llnl.gov
AF: Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, Livermore, Ca 94550
AU: Guilderson, T P
EM: tguilderson@llnl.gov
AF: Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, Livermore, Ca 94550
AU: Guilderson, T P
EM: tguilderson@llnl.gov
AF: Department of Ocean Sciences and Institute of Marine Sciences, University of California, Santa Cruz, Santa Cruz, Ca 95000 United States
AU: Caldeira, K
EM: kenc@llnl.gov
AF: Climate System Modeling Group, Lawrence Livermore National Laboratory, Livermore, Ca 94550 United States
AU: Moore, M
EM: mmoore@uscd.edu
AF: Scripps Institute of Oceanography, Gilman Dr, La Jolla, CA 95000 United States
AB: Radiocarbon has been used as a tracer to study global ocean circulation through the distribution of natural and bomb-derived $^{14}$C. In order to get a complete picture of the temporal variation of $^{14}$C, proxy records, such as those provided by corals are needed. Corals can provide time series of seasonal and interannual $^{14}$C variations of the surface ocean over time scales of hundreds of years. Bi-monthly radiocarbon values from a 115-year time series have been recovered from a coral in the Indonesian Seaway in order to better understand seasonal, interannual and decadal variability in the surface water masses that contribute to the Indonesian Throughflow. The radiocarbon time series occasionally displays a small seasonal signal (10-15 per mil) from 1890 to 1954, with the time period 1875-1880 displaying higher radiocarbon possibly due to a strong El Nino. After 1954 the radiocarbon record increases rapidly, a response to the increased atmospheric $^{14}$C caused by nuclear weapons testing. From 1954 to 1986 the record displays clear seasonal variability from 15 to 60 (per mil). The quick response to the increased atmospheric $^{14}$C and the high post-bomb peak (+160 per mil) indicate a North Pacific source to the waters entering the Indonesian Throughflow. Sensitivity tests were run to investigate the role of surface mixed layer depth and parameterization using an atmosphere/ocean coupled model (GFDL MOM) and compared to the coral radiocarbon time series. The model results exhibit a post-bomb peak that is too high and slightly early but displays the seasonal signal shown by the coral. The model also retains too much radiocarbon after the bomb-peak suggesting the model is exchanging too much CO$_{2}$ and not mixing it through the water column rapidly enough.
DE: 3337 Numerical modeling and data assimilation
DE: 3344 Paleoclimatology
DE: 4215 Climate and interannual variability (3309)
DE: 4283 Water masses
DE: 4504 Air/sea interactions (0312)
SC: Ocean Sciences [OS]
MN: 2003 Fall Meeting