HR: 0800h
AN: OS41B-0482    [Abstracts]
TI: Export and Cycling of Continental Shelf Carbon: A Modeling Study
AU: * Siedlecki, S
EM: siedlesa@uchicago.edu
AF: University of Chicago, Dept. of Geophysical Sciences 5734 S. Ellis Ave, Chicago, IL 60637 United States
AU: Archer, D
EM: d-archer@uchicago.edu
AF: University of Chicago, Dept. of Geophysical Sciences 5734 S. Ellis Ave, Chicago, IL 60637 United States
AU: Mahadevan, A
EM: amala@bu.edu
AF: Boston University, Dept. of Earth Sciences 675 Commonwealth Ave, Boston, MA 02215 United States
AB: Continental margins play a significant role in the production and burial of organic carbon in the ocean, but these areas are poorly resolved in global circulation models. In this study, a high-resolution three-dimensional, nonhydrostatic idealized coastal model of the eastern United States after Mahadevan and Archer, 2000, 1998, was modified to simulate organic carbon production and export off the shelf. The model assumes a periodic north and south boundary, solid offshore and bottom boundaries, and a shelf-break density front determined by bathymetry. The model uses a free surface and a sigma grid in the vertical. We are in the process of formulating a carbon and nutrient component for this model. The model is initialized with a vertical nutrient profile taken from the open Atlantic Ocean. Mesoscale wind-driven circulation and vertical diffusion bring nutrients to the euphotic zone. Primary production is based on light availability and nutrient concentration. The particles advect with the flow and sink with a specified velocity. Remineralization is first-order in carbon concentration, and produces ammonia. Ammonia is slowly reoxidized to nitrate in subsurface waters, and used for recycled production in the euphotic zone. We are searching for a model of the production, sinking, and interconversion of multiple types of particles, which predicts the observed trends in f-ratio from coastal to pelagic ecosystems. The model is sensitive to sinking velocity, remineralization rate, vertical diffusivity, the uptake rate of nitrate, the uptake rate of ammonia, and the oxidation rate of ammonia to nitrate. Using the steady state solution of the one-dimensional model to initialize the three-dimensional model, we study the effect of vertical and horizontal advection and three-dimensional oceanographic processes on the distribution and export of carbon from the coastal system. We will compare the sensitivities of a box-budget, a one-dimensional diffusional, and the full 3-D mesoscale physical model.
DE: 4200 OCEANOGRAPHY: GENERAL
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting