HR: 0830h
AN: OS41B-0807    [PDF]
TI: Intrabasin Comparison of Surface Radiocarbon Levels in the Indian Ocean Between Coral Records and Three-Dimension Global Ocean Models
AU: * Grumet, N S
EM: ngrumet@stanford.edu
AF: Department of Geological and Environmental Sciences, Stanford University, Stanford, CA 94305 United States
AU: Wickett, M E
EM: wickett@llnl.gov
AF: Center for Applied Scientific Computing, Lawrence Livermore National Laboratory, Livermore, CA 94551 United States
AU: Duffy, P B
EM: duffy2@llnl.gov
AF: Energy and Environment Directorate, Lawrence Livermore National Laboratory, Livermore, CA 94551 United States
AU: Caldeira, K
EM: kenc@llnl.gov
AF: Energy and Environment Directorate, Lawrence Livermore National Laboratory, Livermore, CA 94551 United States
AU: Dunbar, R B
EM: dunbar@stanford.edu
AF: Department of Geological and Environmental Sciences, Stanford University, Stanford, CA 94305 United States
AB: We have conducted a model-data comparison between time histories of surface radiocarbon from three-dimension ocean models that participated in the second phase of the Ocean Carbon-Cycle Model Intercomparison Project and observed radiocarbon variability recorded in coral records from the coasts of Kenya and Sumatra. Our coral results show the Kenyan radiocarbon response leading the Sumatran response by 2-3 years during the initial input of bomb C-14. These coral records comprise the first intrabasin record of surface water radiocarbon variability in the equatorial Indian Ocean and provide an independent evaluation of model performance across the Indian Ocean basin. Oceanic uptake and transport of bomb produced radiocarbon is a useful diagnostic in global ocean models to test parameterization of interior mixing and air-sea gas exchange between the ocean and atmosphere. Those models that include a more sophisticated vertical mixing scheme are apparently more capable of matching observed coral radiocarbon time-series. Yet, the large range of model simulation at both sites imply factors such as resolution, topography and physical forcing are more important than choice of mixing parameterization in explaining inter-model differences. None of the models reproduce the time-lag in the rate of bomb C-14 response between the Kenya and Sumatra coral sites. The simulation failure suggests that the lead/lag relationship in the coral records may be a function of small scale processes and/or coastal processes, such as lateral advection, coastal upwelling and rapid mixing with subsurface water, that are difficult to model with a coarse resolution OGCM.
DE: 4203 Analytical modeling
DE: 4231 Equatorial oceanography
DE: 4806 Carbon cycling
DE: 4860 Radioactivity and radioisotopes
SC: Ocean Sciences [OS]
MN: 2003 Fall Meeting