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| Titel |
Factors controlling interannual variability of vertical organic matter export and phytoplankton bloom dynamics – a numerical case-study for the NW Mediterranean Sea |
| VerfasserIn |
R. Bernardello, J. G. Cardoso, N. Bahamon, D. Donis, I. Marinov, A. Cruzado |
| 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 ; 9, no. 11 ; Nr. 9, no. 11 (2012-11-02), S.4233-4245 |
| Datensatznummer |
250007372
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| Publikation (Nr.) |
 copernicus.org/bg-9-4233-2012.pdf |
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| Zusammenfassung |
| Mid-latitude spring blooms of phytoplankton show considerable
year-to-year variability in timing, spatial extent and intensity. It
is still unclear to what degree the bloom variability is connected to
the magnitude of the vertical flux of organic matter. A coupled
three-dimensional hydrodynamic-biogeochemical model is used to relate
interannual variability in phytoplankton spring-bloom dynamics to
variability in the vertical export of organic matter in the NW
Mediterranean Sea. Simulation results from 2001 to 2010, validated
against remote-sensing chlorophyll, show marked interannual
variability in both timing and shape of the bloom. Model results show
a tendency for the bloom to start later after cold and windy
winters. However, the onset of the bloom occurs often when the mixed
layer is still several hundred metres deep while the heat flux is
already approaching zero and turbulent mixing is low. Frequency and
intensity of wind episodes
control both the timing and development of the bloom and the consequent
export flux of organic matter. The wintertime flux is greater than
zero and shows relatively low interannual variability. The magnitude
of the interannual variability is mainly determined in March when the frequency
of windy days positively correlates with the export flux. Frequent
wind-driven mixing episodes act to increase the export flux and, at
the same time, to interrupt the bloom. Perhaps counterintuitively, our analysis shows that years
with discontinuous, low-chlorophyll blooms are likely to have higher
export flux than years with intense uninterrupted blooms. The NW Mediterranean
shows strong analogy with the North Atlantic section
within the same latitude range. Hence, our results may also be applicable
to this quantitatively more important area of the world ocean. |
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