HR: 1340h
AN: A43A-0040    [Abstracts]
TI: Surface Water Circulation in the Indonesian Seas as Reconstructed by High-Resolution Coral Radiocarbon Records
AU: * Fallon, S J
EM: Fallon4@llnl.gov
AF: Center for Accelerator Mass Spectrometry, Lawrence Livermore National Lab 7000 East Ave. L-397, Livermore, Ca 94550 United States
AU: Guilderson, T P
EM: Guilderson1@llnl.gov
AF: Center for Accelerator Mass Spectrometry, Lawrence Livermore National Lab 7000 East Ave. L-397, Livermore, Ca 94550 United States
AU: Guilderson, T P
EM: Guilderson1@llnl.gov
AF: Department of Ocean Sciences and Institute of Marine Sciences, University of California, Santa Cruz, Santa Cruz, Ca 95064 United States
AB: The Indonesian Seas are a main conduit for the redistribution (and modification) of heat and freshwater between the Pacific and Indian Oceans. Through strong coupling between the ocean and atmosphere, variations in the transport and mixing in this region is thought to play an important role in ENSO and the Indonesian/Asian Monsoon on seasonal to decadal timescales. To further elucidate surface water processes including seasonal transport of water from the North Pacific, we have generated $\sim$bimonthly coral-based pre to post-bomb $^{14}$C time-series from Makassar and Lombok Straits, and Bunaken in the Sulawesi Sea. The keystone record is a 115-year time-series from the Makassar Straits. In the pre-bomb (pre-1955) era from 1890 to 1954 surface waters in the Makassar straits display a small and variable seasonal signal (10-15\permil). After 1954 the radiocarbon record increases rapidly, in response to the increased atmospheric $^{14}$C content caused by nuclear weapons testing. From 1954 to 1986 the record displays clear seasonal variability from 15 to 60\permil and the post-bomb peak (163\permil) occurred in 1974. The seasonal cycle of radiocarbon can be attributed to variations of surface waters passing through South Makassar Strait. Southern Makassar experiences two distinct seasons, the Northwest Monsoon which is responsible for the high Austral summer radiocarbon (North Pacific waters) and the Southeast Monsoon that flushes back a mixture of low (South Pacific and an inferred upwelling altered) radiocarbon water from the Banda Sea. The Lombok Strait radiocarbon record displays seasonal influences of Indian Ocean waters and North Pacific waters, while the Bunaken radiocarbon record reflects local influences (upwelling) on the North Pacific water source.
DE: 3339 Ocean/atmosphere interactions (0312, 4504)
DE: 4283 Water masses
DE: 4522 El Ni¤o
DE: 4532 General circulation
DE: 3309 Climatology (1620)
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting