HR: 16:45h
AN: OS52H-10    [PDF]
TI: Ecosystem Composition and Export Production Variability
AU: * Le Quere, C
EM: corinne.lequere@bgc-jena.mpg.de
AF: Max-Planck-Institut for Biogeochemistry, PO Box 10 01 64, Jena, 07701 Germany
AU: Buitenhuis, E T
EM: erik.buitenhuis@bgc-jena.mpg.de
AF: Max-Planck-Institut for Biogeochemistry, PO Box 10 01 64, Jena, 07701 Germany
AU: Klaas, C
EM: christine.klaas@bgc-jena.mpg.de
AF: Max-Planck-Institut for Biogeochemistry, PO Box 10 01 64, Jena, 07701 Germany
AU: Aumont, O
EM: Olivier.Aumont@lodyc.jussieu.fr
AF: LODYC , Universite Pierre et Marie Curie, 4 Place Jussieu, Paris, 75005 France
AB: Carbon-cycle models predict that climate change will reduce the oceanic CO$_{2} \sim10$\% sink by in 50-100 year time-scale. The models used so far, however, allow only small changes in ecosystem composition. Here we evaluate the degree to which models are able to reproduce observed year-to-year variations in surface chlorophyll and in export production. We discuss the behavior of four models of increasing complexity, starting from a simple nutrient-based model (HAMOCC3) and going to a more complex Dynamic Green Ocean model that includes five plankton functional types and two sizes of sinking particles. All models analyzed underestimate the observed variability compared to surface chla from SeaWiFS and to sediment trap fluxes, especially at high latitudes and during blooms. The Dynamic Green Ocean model is the most variable of the models analyzed, although patterns are still far from observations. This suggests that the ecosystem composition does impact export production on a year-to-year basis and may affect the air-sea CO$_{2}$ fluxes in the future, although no quantitative estimates can be reliably done yet. We discuss possible upper bounds based on observed and modelled year-to-year variations.
DE: 1615 Biogeochemical processes (4805)
DE: 4806 Carbon cycling
DE: 4815 Ecosystems, structure and dynamics
DE: 4842 Modeling
DE: 4845 Nutrients and nutrient cycling
SC: Ocean Sciences [OS]
MN: 2004 Ocean Sciences Meeting