HR: 0800h
AN: OS51A-0557    [Abstracts]
TI: How do Particle Dynamics on a Passive Margins Influence the Coastal Organic Carbon Cycle?: An Idealized Model of the East Coast of the United States
AU: * Deringer, S A
EM: siedlesa@uchicago.edu
AF: University of Chicago, Dept. of Geophysical Sciences 5734 S. Ellis Ave, Chicago, IL 60637 United States
AU: Archer, D E
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 One Sherborn Street, Boston, MA 02215 United States
AB: The coastal ocean only represents 8% of the global ocean, but the amount of carbon produced and buried there makes it an important part of the global carbon cycle. It contributes18-33% to the production of the whole ocean and the rate of organic carbon fluxes to the seafloor, or benthic fluxes, exceed those in the open ocean by an order of magnitude [Wollast, 1991; Jahnke et al., 1990]. Approximately 90% of organic carbon burial occurs shallower than 1000m water depth [Archer et al., 2002]. We use a three-dimensional, nonhydrostatic, high-resolution model after the East coast of the United States is used to simulate the general patterns of the passive East Coast margin in order to study the impact of the dynamics of sinking particles on the coastal ocean organic carbon cycle. Specifically, the role of offshore and onshore movement of organic carbon rich particles as a function of the wind direction. The dynamical model is after Mahadevan et al, 1996a; Mahadevan et al, 1996b; Mahadevan and Archer, 1998. The model uses a sigma grid with periodic north and south boundaries and 1km resolution. The onshore, offshore, and bottom boundaries are closed. The model is run with both wind fields from buoy data and forced wind fields. Three forms of nitrogen exist in the model: Nitrate, ammonia, and particulate. The model is initialized with a steady state nitrate profile resulting from a one-dimensional study with the same biogeochemical subroutine. Each of the two nutrients has its own uptake time scale taken from the literature. The two forms of nutrients allow for the f-ratio to be operationally calculated as done in the field. Production results from the uptake of the nutrients in the euphotic zone and it produces particles. Primary production makes small (suspended) particles, which coagulate into a large particle pool and sink. They coagulate according to a simple scheme similar to Jackson, 1995. The rate of decay decreases with depth. A preliminary result is that with an increase in production driven by coastal upwelling, the f-ratio increases due to the increase in available nitrate from depth. In addition, increased total production increases coagulation fluxes, thus increasing the f-ratio. Archer, D.E., Morford, J.L., and S.R. Emerson, A model of suboxic sedimentary diagenesis suitable for automatic tuning and gridded global domains, Global Biogeochemical Cycles. 16, 10.1029/2000GB001288, 2002. Jackson, G.A., Comparing observed changes in particle size spectra with those predicted using coagulation theory, DSR II. 42. 159-184, 1995. Jahnke, R.A., C.E. Reimers, and D.B. Craven, Intensification of recycling of organic matter at the sea floor near ocean margins, Nature. 348, 50-54, 1990. Mahadevan, A., and D. Archer, Modeling a limited region of the ocean, J. Comp. Phys. 145, 555-574, 1998. Mahadevan, A., J. Oliger, and R. Street, A well-posed model for mesoscale oceanographic flow. 1: Well-posedness and scaling, J. Physical Oceanogr. 26,(9), 1168-1880 , 1996a. Mahadevan, A., J. Oliger, and R. Street, A well-posed model for mesoscale oceanographic flow. 2: Numerical implementation, J. Physical Oceanogr. 26, (9), 1181-1900, 1996b. Wollast, R., J.-M. Martin and R. Wollast (eds), The coastal carbon cycle: Fluxes, sources, and sinks. In: Ocean Margin Processes in Global Change. Wiley, New York, 1991.
DE: 4217 Coastal processes
DE: 4805 Biogeochemical cycles, processes, and modeling (0412, 0414, 0793, 1615, 4912)
DE: 4806 Carbon cycling (0428)
SC: Ocean Sciences [OS]
MN: Fall Meeting 2005