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| Titel |
Optimizing models of the North Atlantic spring bloom using physical, chemical and bio-optical observations from a Lagrangian float |
| VerfasserIn |
W. Bagniewski, K. Fennel, M. J. Perry, E. A. D'Asaro |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 8, no. 5 ; Nr. 8, no. 5 (2011-05-25), S.1291-1307 |
| Datensatznummer |
250005823
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| Publikation (Nr.) |
 copernicus.org/bg-8-1291-2011.pdf |
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| Zusammenfassung |
| The North Atlantic spring bloom is one of the main events that lead to carbon
export to the deep ocean and drive oceanic uptake of CO2 from the
atmosphere. Here we use a suite of physical, bio-optical and chemical
measurements made during the 2008 spring bloom to optimize and compare three
different models of biological carbon export. The observations are from a
Lagrangian float that operated south of Iceland from early April to late
June, and were calibrated with ship-based measurements. The simplest model is
representative of typical NPZD models used for the North Atlantic, while the
most complex model explicitly includes diatoms and the formation of fast
sinking diatom aggregates and cysts under silicate limitation. We carried out
a variational optimization and error analysis for the biological parameters
of all three models, and compared their ability to replicate the
observations. The observations were sufficient to constrain most
phytoplankton-related model parameters to accuracies of better than 15 %.
However, the lack of zooplankton observations leads to large uncertainties in
model parameters for grazing. The simulated vertical carbon flux at 100 m
depth is similar between models and agrees well with available observations,
but at 600 m the simulated flux is larger by a factor of 2.5 to 4.5 for the model with diatom
aggregation. While none of the models can be formally rejected based on their
misfit with the available observations, the model that includes export by
diatom aggregation has a statistically significant better fit to the observations and more
accurately represents the mechanisms and timing of carbon export based on
observations not included in the optimization. Thus models that accurately
simulate the upper 100 m do not necessarily accurately simulate export to
deeper depths. |
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