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| Titel |
On the relationship between Southern Ocean eddies and phytoplankton |
| VerfasserIn |
Ivy Frenger, Matthias Münnich, Nicolas Gruber |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250148166
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| Publikation (Nr.) |
 EGU/EGU2017-12400.pdf |
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| Zusammenfassung |
| Effects on phytoplankton in the Southern Ocean are crucial for the global ocean nutrient
and carbon cycles. Such effects potentially arise from mesoscale eddies which are
omnipresent in the region. Eddies are known to affect phytoplankton through either
advection and mixing, or the stimulation/suppression of growth. Yet, the climatological
relationship between Southern Ocean eddies and phytoplankton has not been quantified in
detail.
To provide an estimate of this relationship, we identified more than100,000 eddies in the
Southern Ocean and determined associated phytoplankton anomalies using satellite-based
chlorophyll-a (chl) measurements. The eddies have a very substantial impact on the chl
levels, with eddy associated chl differing by more than 10% from the background over wide
areas. The structure of these anomalies is largely zonal, with positive anomalies north of the
Antarctic Circumpolar Current (ACC) and negative anomalies within the circumpolar belt of
the ACC for cyclonic eddies. The pattern is similar but of opposite sign for anticyclonic
eddies. The seasonality of this signal is weak north to the ACC, but pronounced in the
vicinity of the ACC. The spatial structure and seasonality of the signal can be explained
largely by advection, i.e., the eddy-circulation driven lateral transport of anomalies across
large-scale gradients. We conclude this based on the shape of local chl anomalies of
eddies and ambient chl gradients. In contrast, ACC winter anomalies are consistent
with an effect of eddies on the light exposure of phytoplankton. The clear impact
of eddies on chl implies a downstream effect on Southern Ocean biogeochemical
properties. |
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