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| Titel |
The role of phytoplankton dynamics in the seasonal and interannual variability of carbon in the subpolar North Atlantic – a modeling study |
| VerfasserIn |
S. R. Signorini, S. Häkkinen, K. Gudmundsson, A. Olsen, A. M. Omar, J. Olafsson, G. Reverdin, S. A. Henson, C. R. McClain, D. L. Worthen |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1991-959X
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| Digitales Dokument |
URL |
| Erschienen |
In: Geoscientific Model Development ; 5, no. 3 ; Nr. 5, no. 3 (2012-05-15), S.683-707 |
| Datensatznummer |
250002612
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| Publikation (Nr.) |
 copernicus.org/gmd-5-683-2012.pdf |
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| Zusammenfassung |
| We developed an ecosystem/biogeochemical model system, which includes
multiple phytoplankton functional groups and carbon cycle dynamics, and
applied it to investigate physical-biological interactions in Icelandic
waters. Satellite and in situ data were used to evaluate the model. Surface
seasonal cycle amplitudes and biases of key parameters (DIC, TA,
pCO2, air-sea CO2 flux, and nutrients) are significantly improved
when compared to surface observations by prescribing deep water values and
trends, based on available data. 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 phytoplankton, 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, in agreement with previous studies. The
inclusion of multiple phytoplankton 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. During the
peak of the bloom in summer, 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. On average, the impact of coccolithophores is an increase of
air-sea CO2 flux of about 27%. Considering the areal extent of the
bloom from satellite images within the Irminger and Icelandic Basins, this
reduction translates into an annual mean of nearly 1500 tonnes C yr−1. |
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