Article (Scientific journals)
Climate oscillations evidenced by spectral analysis of Southern Chilean lacustrine sediments: the assessment of ENSO over the last 600 years
Fagel, Nathalie; Boes, X.; Loutre, M. F.
2008In Journal of Paleolimnology, 39 (2), p. 253-266
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Keywords :
El Nino Southern Oscillation (ENSO); spectral analysis; lacustrine sediment; varve; Chile; Last millennium; Little Ice Age
Abstract :
[en] The Chilean Lake District (38-42 degrees S) is strongly influenced by Southern westerlies-driven precipitations. At 40 degrees S Lago Puyehue provides high resolution sedimentation rates (similar to 1-2 mm/yr) suitable for annual climate reconstruction. Several short and long sediment cores were collected in this lake. Their analysis aim at a better understanding of climate mechanisms related to ENSO in this part of the world. The recognition of ENSO related periodicities and their stability is studied through the analysis of two short varved cores collected from underflow and interflow key sites. According to varve chronology controlled by Cs-137 and Pb-210 profiles and chronostratigraphical markers, the short core from underflow site (PU-I) spans 294 +/- 18 years and the core in the interflow site (PU-II) covers 592 +/- 9 years. Several methods of spectral analysis were applied on the total varve thickness to identify potential periodicities in the signal. Blackman-Tuckey, Maximum Entropy, Multi-Taper Methods (MTM) and singular spectrum analysis were applied on the whole record. In addition, evolutive MTM and wavelet analyses allow to identify temporal influence of some periodicities. In the PU-I studied interval (AD 1700-2000), a period at similar to 3.0 years appears in a large part of the interval, mostly in the recent part. Periods at similar to 5.2 and similar to 23 years also show up. PU-II record (AD 1400-2000) displays the most robust periodicities at around 15, 9, 4.4, 3.2 and 2.4 years. These periodicities are in good agreement with the sub-decadal periods identified by Dean and Kemp (2004) and linked to the El Nino Southern Oscillation and the Pacific Decadal Oscillation. Differences in the recorded periodicities between PU-I and PU-II sites are consistent with different sedimentation processes in the lake. According to climate instrumental data for the last 20 years, varves in PU-I site are mostly related to fluvial dynamics and regional climate factors, i.e., precipitation, temperature and wind. In PU-II site, varves increment is related to both regional and global climate forcing factors, i.e., El Nino Southern Oscillation. The evolutive MTM analysis and the wavelet analysis suggest a striking break in the periodicities at around AD 1820. Finally relationships between El Nino and longer term climate phase like the Little Ice Age (LIA) are also assessed.
Disciplines :
Earth sciences & physical geography
Environmental sciences & ecology
Physical, chemical, mathematical & earth Sciences: Multidisciplinary, general & others
Aquatic sciences & oceanology
Author, co-author :
Fagel, Nathalie  ;  Université de Liège - ULiège > Département de géologie > Argiles, géochimie et environnements sédimentaires
Boes, X.
Loutre, M. F.
Language :
English
Title :
Climate oscillations evidenced by spectral analysis of Southern Chilean lacustrine sediments: the assessment of ENSO over the last 600 years
Publication date :
2008
Journal title :
Journal of Paleolimnology
ISSN :
0921-2728
eISSN :
1573-0417
Publisher :
Springer Science & Business Media B.V.
Volume :
39
Issue :
2
Pages :
253-266
Peer reviewed :
Peer Reviewed verified by ORBi
Funders :
SSTC - Services Fédéraux des Affaires Scientifiques, Techniques et Culturelles [BE]
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