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| Titel |
Tropical Pacific spatial trend patterns in observed sea level: internal variability and/or anthropogenic signature? |
| VerfasserIn |
B. Meyssignac, D. Salas y Melia, M. Becker, W. Llovel, A. Cazenave |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 8, no. 2 ; Nr. 8, no. 2 (2012-04-18), S.787-802 |
| Datensatznummer |
250005484
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| Publikation (Nr.) |
 copernicus.org/cp-8-787-2012.pdf |
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| Zusammenfassung |
| In this study we focus on the sea level trend pattern observed by satellite
altimetry in the tropical Pacific over the 1993–2009 time span (i.e. 17 yr). Our objective is to investigate whether this 17-yr-long trend
pattern was different before the altimetry era, what was its spatio-temporal
variability and what have been its main drivers. We try to discriminate the
respective roles of the internal variability of the climate system and of
external forcing factors, in particular anthropogenic emissions (greenhouse
gases and aerosols). On the basis of a 2-D past sea level reconstruction
over 1950–2009 (based on a combination of observations and ocean
modelling) and multi-century control runs (i.e. with constant,
preindustrial external forcing) from eight coupled climate models, we
have investigated how the observed 17-yr sea level trend pattern evolved during
the last decades and centuries, and try to estimate the characteristic time
scales of its variability. For that purpose, we have computed sea level trend
patterns over successive 17-yr windows (i.e. the length of the altimetry
record), both for the 60-yr long reconstructed sea level and the model
runs. We find that the 2-D sea level reconstruction shows spatial trend
patterns similar to the one observed during the altimetry era. The pattern
appears to have fluctuated with time with a characteristic time scale of the
order of 25–30 yr. The same behaviour is found in multi-centennial control
runs of the coupled climate models. A similar analysis is performed with
20th century coupled climate model runs with complete external forcing (i.e. solar plus
volcanic variability and changes in anthropogenic forcing). Results suggest that in the tropical Pacific, sea level
trend fluctuations are dominated by the internal variability of the
ocean–atmosphere coupled system. While our analysis cannot rule out any
influence of anthropogenic forcing, it concludes that the latter effect
in that particular region is stillhardly detectable. |
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