Modes of eastern equatorial Pacific thermocline variability: Implications for ENSO dynamics over the last glacial period.

Leduc, G., Vidal, L., Cartapanis, O. and Bard, E. (2009) Modes of eastern equatorial Pacific thermocline variability: Implications for ENSO dynamics over the last glacial period. Paleoceanography, 24 . DOI Pa3202 10.1029/2008pa001701.

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Abstract

Changes in El Nino-Southern Oscillation (ENSO) variability are difficult to extract from paleoceanographic reconstructions because they are superimposed on changes in seasonal variability that modulate the first-order climate signal. Here we address this problem by reconstructing thermocline structure from a marine sediment core retrieved from the eastern equatorial Pacific. At the core location, changes in hydrologic parameters within the thermocline are linked to ENSO activity, with a reduced influence of seasonal variability compared to surface waters. We performed repeated isotopic analyses (delta(18)O) on single specimens of the thermocline-dwelling planktonic foraminifera Neogloboquadrina dutertrei at several targeted time periods over the last 50 ka to extract the total thermocline variance, a parameter supposed to reveal changes in ENSO. No fundamental changes in amplitude and frequency of the events were detected despite differences in climatic background. However, our data suggest that long-term variations in the thermocline variability occurred over the last 50 ka, with the highest and lowest ENSO activities occurring during the last glacial period and the Last Glacial Maximum, respectively.

Document Type: Article
Keywords: el-nino/southern-oscillation nino-southern oscillation pmip2 coupled simulations sea-surface temperature abrupt climate-change tropical pacific planktonic-foraminifera panama basin individual foraminifera vertical-distribution
Research affiliation: Kiel University
Refereed: No
DOI etc.: Pa3202 10.1029/2008pa001701
ISSN: 0883-8305
Date Deposited: 22 Dec 2011 05:57
Last Modified: 08 Oct 2012 10:10
URI: http://oceanrep.geomar.de/id/eprint/15798

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