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www.geosci-model-dev-discuss.net/4/289/2011/
doi:10.5194/gmdd-4-289-2011
© Author(s) 2011. This work is distributed
under the Creative Commons Attribution 3.0 License.
The role of phytoplankton dynamics in the seasonal variability of carbon in the subpolar North Atlantic – a modeling study
1Science Applications International Corp., Beltsville, Maryland, USA
2NASA Goddard Space Flight Center, Cryospheric Sciences Branch, Greenbelt, Maryland, USA
3Marine Research Institute, P.O. Box 1390, 121 Reykjavik, Iceland
4Uni Bjerknes Centre, Allégaten 55, 5007 Bergen, Norway
5Bjerknes Centre for Climate Research, Allégaten 55, 5007 Bergen, Norway
6University of Iceland and Marine Research Institute, Reykjavik, Iceland
7Laboratoire d'Océanographie Dynamique et de Climatologie, IPSL, Boîte 100 – 4, Place Jussieu 75252, Paris, France
8National Oceanographic Centre, European Way, Southampton, SO14 3ZH, UK
9NASA Goddard Space Flight Center, Ocean Ecology Branch, Greenbelt, Code 614.2, Maryland, USA
Abstract. We use an ecosystem/biogeochemical model, which includes multiple phytoplankton functional groups and carbon cycle dynamics, to investigate physical-biological interactions in Icelandic waters. Satellite and in situ data were used to validate the model. The seasonality of the coccolithophore and "other phytoplankton" (diatoms and dinoflagellates) blooms is in general agreement with satellite ocean color products. Nutrient supply, biomass and calcite concentrations are modulated by light and mixed layer depth seasonal cycles. Diatoms are the most abundant with a large bloom in early spring and a secondary bloom in fall. The diatom bloom is followed by blooms of dinoflagellates and coccolithophores. The effect of biological changes on the seasonal variability of the surface ocean pCO2 is nearly twice the temperature effect. The inclusion of multiple functional groups in the model played a major role in the accurate representation of CO2 uptake by biology. For instance, at the peak of the bloom, the exclusion of coccolithophores causes an increase in alkalinity of up to 4 μmol kg−1 with a corresponding increase in DIC of up to 16 μmol kg−1. The net effect of the absence of the coccolithophores bloom is an increase in pCO2 of more than 20 μatm and a reduction of atmospheric CO2 uptake of more than 6 mmol m−2 d−1.
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Notice on Discussion StatusCitation: Signorini, S. R., Häkkinen, S., Gudmundsson, K., Olsen, A., Omar, A. M., Olafsson, J., Reverdin, G., Henson, S. A., and McClain, C. R.: The role of phytoplankton dynamics in the seasonal variability of carbon in the subpolar North Atlantic – a modeling study, Geosci. Model Dev. Discuss., 4, 289-342, doi:10.5194/gmdd-4-289-2011, 2011. Bibtex EndNote Reference Manager XML
