HR: 1340h
AN: NG33C-0189    [Abstracts]
TI: Mesoscale turbulence effects on transport of marine biogeochemical tracers.
AU: * Pasquero, C
EM: claudia@gps.caltech.edu
AF: California Institute of Techonology, MC 100-23, Pasadena, CA 91125 United States
AB: Nutrient supply for the marine ecosystem in the upper ocean is controlled by vertical and lateral transport from nutrient rich waters. Both processes are affected by the turbulent characteristics of the oceanic flow. We here investigate some of the effects that mesoscale turbulence has on transport of biogeochemical tracers, and discuss their parameterization in large scale models. To this end, a simple ecosystem model (Nutrient-Phytoplankton-Zooplankton) is coupled to different fluid dynamical models of the upper ocean. We test the validity of the eddy diffusion parameterization - often used to represent the mixing effect associated to the presence of unresolved turbulent structures - in presence of inhomogeneous concentrations of the biogeochemical fields. We show that the parameterization can be profitably used, provided that an effective eddy diffusion coefficient that depends on the reaction time scale of the transported tracers is used. If the diffusion coefficient valid for conservative tracers is used to express diffusion of nutrients and plankton, turbulent transport can be significantly overestimated. The results presented here are relevant for any advection-reaction system, whose advection and reaction time scales are not fully separated.
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 4273 Physical and biogeochemical interactions
DE: 4490 Turbulence (3379, 4568, 7863)
DE: 4805 Biogeochemical cycles, processes, and modeling (0412, 0414, 0793, 1615, 4912)
SC: Nonlinear Geophysics [NG]
MN: Fall Meeting 2005