We
have developed a multiple element (C, N, P, Si, Ca, Fe) biogeochemical model of
marine ecology that includes small, large and diazotrophic phytoplankton as
well as explicit ballast-driven sinking and remineralization of detrital
organic matter and cycling of dissolved organic matter. Phytoplankton growth is
described through a new formulation including co-limitation by N, P, Si, Fe and
light to reproduce broad observational trends.
Phytoplankton grazing is described through different power laws in the
closure terms for small and large phytoplankton to reproduce observed
augmentation of large phytoplankton with increasing production. Detritus
production is assumed to be a temperature dependent fraction of small and large
phytoplankton. This model has been imbedded in a 1-degree; global ice/ocean
general circulation model (MOM4) forced by a 43-year atmospheric reanalysis
forcing from the Common Ocean Reference Experiments (CORE) program to quantify
the relationship between food web structure, biogeochemical cycles and the
atmospheric CO2 signature on inter-annual timescales. Novel aspects
in the model structure are described, the impact of the formulation of
ecosystem structure on biogeochemical cycling are discussed, and results of the
atmospheric reanalysis forcing experiment presented. Of particular interest are
the dynamical roles played by equatorial ENSO variability and polar sea ice
dynamics on air-sea CO2 fluxes.
Author: J.P. Dunne, R.A. Armstrong, A. Gnanadesikan, et al (John dot Dunne at noaa dot gov)
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