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          Institute: MPI für Meteorologie     Collection: Ocean in the Earth System     Display Documents



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ID: 174026.0, MPI für Meteorologie / Ocean in the Earth System
An ecosystem model of the global ocean including Fe, Si, P colimitations
Authors:Aumont, O.; Maier-Reimer, Ernst; Blain, S.; Monfray, P.
Language:English
Date of Publication (YYYY-MM-DD):2003-06-04
Title of Journal:Global Biogeochemical Cycles
Journal Abbrev.:Glob. Biogeochem. Cycle
Volume:17
Issue / Number:2
Sequence Number of Article:1060
Review Status:Peer-review
Audience:Not Specified
Abstract / Description:Observations have shown that large areas of the world ocean are characterized by lower than expected chlorophyll concentrations given the ambient phosphate and nitrate levels. In these High Nutrient-Low Chlorophyll regions, limitations of phytoplankton growth by other nutrients like silicate or iron have been hypothesized and further evidenced by in situ experiments. To explore these limitations, a nine-component ecosystem model has been embedded in the Hamburg model of the oceanic carbon cycle (HAMOCC5). This model includes phosphate, silicate, dissolved iron, two phytoplankton size fractions (nanophytoplankton and diatoms), two zooplankton size fractions (microzooplankton and mesozooplankton), one detritus and semilabile dissolved organic matter. The model is able to reproduce the main characteristics of two of the three main HNLC areas, i.e., the Southern Ocean and the equatorial Pacific. In the subarctic Pacific, silicate and phosphate surface concentrations are largely underestimated because of deficiencies in ocean dynamics. The low chlorophyll concentrations in HNLC areas are explained by the traditional hypothesis of a simultaneous iron-grazing limitation: Diatoms are limited by iron whereas nanophytoplankton is controlled by very efficient grazing by microzooplankton. Phytoplankton assimilates 18 x 10(9) mol Fe yr(-1) of which 73% is supplied by regeneration within the euphotic zone. The model predicts that the ocean carries with it about 75% of the phytoplankton demand for new iron, assuming a 1% solubility for atmospheric iron. Finally, it is shown that a higher supply of iron to surface water leads to a higher export production but paradoxically to a lower primary productivity.
Comment of the Author/Creator:Date: 2003, JUN 4
External Publication Status:published
Document Type:Article
Communicated by:Carola Kauhs
Affiliations:MPI für Meteorologie/Physical Climate System
External Affiliations:UPMC, IRD, Unite Mixte CNRS, Lab Oceanog Dynam & Climatol, F-75252 Paris, France.; Inst Univ Europeen Mer, F-29280 Plouzane, France.; Max Planck Inst Meteorol, D-20146 Hamburg, Germany.; Ctr Etud Saclay, Lab Sci Climat & Environm, F-91191 Gif Sur Yvette, France.
Identifiers:ISI:000183554600001 [ID No:1]
ISSN:0886-6236 [ID No:2]
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