Multiscale monsoon variability during the last two climatic cycles revealed by spectral signals in Chinese loess and speleothem records

Li, Y., Su, N., Liang, L., Ma, L., Yan, Y., and Sun, Y. (2015) Multiscale monsoon variability during the last two climatic cycles revealed by spectral signals in Chinese loess and speleothem records. Climate of the Past, 11 (8). pp. 1067-1075.

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The East Asian Monsoon (EAM) exhibits a significant variability on timescales ranging from tectonic to centennial as inferred from loess, speleothem and marine records. However, the relative contributions and plausible driving forces of the monsoon variability at different timescales remain controversial. Here, we spectrally explore time series of loess grain size and speleothem δ¹⁸O records and decompose the two proxies into intrinsic components using the empirical mode decomposition method. Spectral results of these two proxies display clear glacial and orbital periodicities corresponding to ice volume and solar cycles, and evident millennial signals which are in pace with Heinrich rhythm and Dansgaard–Oeschger (DO) cycles. Five intrinsic components are parsed out from loess grain size and six intrinsic components from speleothem δ¹⁸O records. Combined signals are correlated further with possible driving factors including the ice volume, insolation and North Atlantic cooling from a linear point of view. The relative contributions of components differ significantly between loess grain size and speleothem δ¹⁸O records. Coexistence of glacial and orbital components in the loess grain size implies that both ice volume and insolation have distinctive impacts on the winter monsoon variability, in contrast to the predominant precessional impact on the speleothem δ¹⁸O variability. Moreover, the millennial components are evident in loess grain size and speleothem δ¹⁸O records with variances of 13 and 17 %, respectively. A comparison of the millennial-scale signals of these two proxies reveals that abrupt changes in the winter and summer monsoons over the last 260 kyr share common features and similar driving forces linked to high-latitude Northern Hemisphere climate.

Item ID: 43009
Item Type: Article (Research - C1)
ISSN: 1814-9332
Keywords: monsoon variability, last climatic cycles, multiscale spectral analysis, Chinese loess, speleothem records
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© Author(s) 2015. This work is distributed under the Creative Commons Attribution 3.0 License.

Funders: National Basic Research Program of China (NBRPC), Chinese Academy of Sciences (CAS), National Natural Science Foundation of China (NNSFC), State Key Laboratory of Loess and Quaternary Geology (SKLLQG)
Projects and Grants: NBRPC 2013CB955904, CAS KZZD-EW25 TZ-03, NNSFC 41472163, SKLLQG1011
Date Deposited: 02 Mar 2016 04:34
FoR Codes: 04 EARTH SCIENCES > 0403 Geology > 040303 Geochronology @ 40%
04 EARTH SCIENCES > 0402 Geochemistry > 040203 Isotope Geochemistry @ 30%
01 MATHEMATICAL SCIENCES > 0199 Other Mathematical Sciences > 019999 Mathematical Sciences not elsewhere classified @ 30%
SEO Codes: 96 ENVIRONMENT > 9603 Climate and Climate Change > 960304 Climate Variability (excl. Social Impacts) @ 50%
96 ENVIRONMENT > 9602 Atmosphere and Weather > 960202 Atmospheric Processes and Dynamics @ 50%
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