Centennial-to-Millennial-Scale Periodicities in East Asian Monsoon Climate During the Holocene
M Sarnthein (Geologisch-Palaeontologisches Institut, Universitaet Kiel, D-24118 Kiel, Germany; ph. 49-431-8802851; fax 49-431-8804376; Internet: firstname.lastname@example.org) ; L Wang (Graduate School of Environmental Earth Science Hokkaido University, Japan; ph. 81-11- 7065303; fax: 81-11-7065303; Internet: email@example.com) ; H Erlenkeuser (Leibniz Labor, Universitaet Kiel, D-24118 Kiel, Germany; ph. 49-431-8803896; fax 49-431-8803356; Internet: HErlenkeuser@leibniz.uni-kiel.de) ; P Grootes (Leibniz Labor, Universitaet Kiel D-24118 Kiel, Germany; ph. 49-431-8803894; fax 49-431-8803356; Internet: firstname.lastname@example.org) (AGU Sponsor: P Grootes)
Centennial-scale variations in the Holocene monsoon climate of South China are deduced from ultrahigh-resolution stable-isotope, paleotemperature (SST), and paleosalinity (SSS) records of SONNE core 17940 adjacent to the freshwater plume of the Pearl River (20-40-yr sampling resolution) and compared with similar ultrahigh-resolution records in the Arabian and Nordic Seas. The SSS record, which is unaffected by local shifts in the shoreline, shows uniform variations of ± 0.7ë around the Holocene average over the last 10 ka (dated by 26 AMS-C14 ages). These high frequency fluctuations suggest periodic changes in the East Asian monsoon regime, with a period far below the established range of orbital climate forcing via the Milankovitch cycles. In the frequency domain the SSS variations contain strong cyclicities at periods of 775 years and 102/84 years, which exceed red noise at the 80% confidence level. Similar periodicities also occur during stages 2 and 3, but were not precisely identified because of a still insufficient time control of this section in core 17940. The 775-year period is approximately one quarter of the 3000-year cycle identified in the local SST record and one half of the salient 1,500-yr cyclicity, found in sediment records from the Arabian Sea (Sirocko et al., 1996) and the North Atlantic (Bond et al., 1997; Voelker, in prep.) and in particular, in the d18O record of stages 2 and 3 in the GISP2 ice core from Greenland (Grootes and Stuiver, 1997). The 775-yr periodicity might thus be regarded as a harmonic period of the 1500-yr cycles. The period of 102/84 years may be assigned to the Gleissberg cycle of solar activity, which is frequent in a number of ultrahigh-resolution records such as tree-ring ?14C and the GISP2 ice core (Grootes and Stuiver, 1996). However, compilations by Stocker (1996) show that a consistent theory on climatic cycles on the decadal-to-century time scale is still missing. Accordingly, the centennial periodicities in the Holocene variation of East Asian monsoon can be ascribed only tentatively to internal forcing mechanisms such as 1) subharmonics of secondary Milankovitch cycles, driven via the global thermohaline circulation in the ocean, and 2) short-term changes in solar activity (Wang et al., in prep.).