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| Titel |
Circulation, eddies, oxygen, and nutrient changes in the eastern tropical South Pacific Ocean |
| VerfasserIn |
R. Czeschel, L. Stramma, R. A. Weller, T. Fischer |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1812-0784
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| Digitales Dokument |
URL |
| Erschienen |
In: Ocean Science ; 11, no. 3 ; Nr. 11, no. 3 (2015-06-22), S.455-470 |
| Datensatznummer |
250117228
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| Publikation (Nr.) |
 copernicus.org/os-11-455-2015.pdf |
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| Zusammenfassung |
| A large subsurface oxygen deficiency zone is located in the eastern tropical South Pacific Ocean (ETSP). The large-scale circulation in the
eastern equatorial Pacific and off the coast of Peru in November/December 2012 shows the
influence of the equatorial current system, the eastern boundary currents,
and the northern reaches of the subtropical gyre. In November 2012 the
equatorial undercurrent (EUC) is centered at 250 m depth, deeper than in earlier
observations. In December 2012, the equatorial water is transported
southeastward near the shelf in the Peru–Chile undercurrent (PCUC) with a mean
transport of 1.4 Sv. In the oxygen minimum zone (OMZ), the flow is overlaid
with strong eddy activity on the poleward side of the OMZ. Floats with
parking depth at 400 m show fast westward flow in the mid-depth equatorial
channel and sluggish flow in the OMZ. Floats with oxygen sensors clearly
show the passage of eddies with oxygen anomalies. The long-term float
observations in the upper ocean lead to a net community production estimate
at about 18° S of up to 16.7 mmol C m−3 yr−1
extrapolated to an annual rate and 7.7 mmol C m−3 yr−1 for the
time period below the mixed layer. Oxygen differences between repeated ship
sections are influenced by the Interdecadal Pacific Oscillation (IPO), by the
phase of El Niño, by seasonal changes, and by eddies, and hence have to
be interpreted with care. At and south of the Equator the decrease in oxygen
in the upper ocean since 1976 is related to an increase in nitrate,
phosphate, and in part silicate. |
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