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| Titel |
Observation of spiciness interannual variability in the Pacific pycnocline |
| VerfasserIn |
Nicolas Kolodziejczyk, Fabienne Gaillard |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250076671
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| Zusammenfassung |
| Monthly gridded fields predominantly based on global Argo in situ temperature and salinity
data are used to analyze the density-compensated anomaly of salinity (spiciness anomaly) in
the pycnocline of the subtropical and tropical Pacific Ocean between 2004 and 2011.
Interannual variability in the formation, propagation and fate of spiciness anomalies are
investigated. The spiciness anomalies propagate on the isopycnal surface Ïăθ = 25.5 along the
subtropical-tropical pycnocline advected by the mean currents. They reach the Pacific
Western Tropics in about 5-6 years in the Southern Hemisphere and about 7-8 years
in the Northern Hemisphere. Their amplitude strongly diminishes along the way
and only very weak spiciness anomalies seem to reach the equator in the Western
Tropics A complex-EOF analysis of interannual salinity anomalies on Ïăθ = 25.5
highlights two dominant modes of variability at interannual scale: i) the former shows a
variability of 5-7 years predominant in the Northern Hemisphere, and ii) the latter
displays an interannual variability of 2 to 3 years more marked in the Southern
Hemisphere. The significant correlation of this second mode with ENSO index
suggests that spiciness formation in the South-Eastern Pacific (SEP) is affected by
ENSO tropical interannual variability. A diagnosis of the mechanisms governing the
interannual generation of spiciness in the SEP region leads the authors to suggest that the
spiciness interannual variability in the sub-surface is linked to the equatorward
migration of the isopycnal outcrop line Ïăθ = 25.5 into the area of maximum salinity.
Quantitative analysis based on Turner angle reveals the dominance of the spiciness
injection mechanism occurring through convective mixing at the base of mixed
layer. |
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