Ice-Volume Forcing of East Asian Winter Monsoon Variations in the Past 800,000 Years

Abstract

Particle-size measurements of some typical loess-soil samples taken in different localities of the Chinese Loess Plateau demonstrate that the grain size ratio of <2 μm/>10 μm (%) can be used as an indicator of variations in intensity of the East Asian winter monsoon winds. Grain-size curves of the Baoji and Weinan sections show that this proxy indicator is very sensitive to loess-soil alterations. Analytical results also suggest that during soil-forming periods, eolian dust accumulation was still substantial and, hence, loess deposition can be regarded as a nearly continuous process during the Quaternary period. In this study we compared the Baoji grain-size time series with the SPECMAP marine isotope record with the objective of elucidating the dynamic linkage between changes in global ice volume and the winter monsoon circulation. Both records show good agreement at both time and frequency domains. In particular, the winter monsoon variations are also dominated by a 100,000 yr period over the past 800,000 yr. It is thus inferred that direct local insolation forcing could be less important in driving the East Asian winter monsoon variability, and, alternatively, variations in glacial-age boundary conditions may have played a key role in modulating and pacing its strength and timing.

Distinct responses of East Asian summer and winter monsoons to astronomical forcing

“…The EAM system is fundamentally influenced by the astronomical scale in both direct insolation forcing and variations in global ice volume ). In the last 800 000 years, a strong 100-ka period consistent with global ice volume cycles is clearly found in the grain size records of Chinese loess, which indicates that the EAM system might be dominated by the changes in glacialage boundary conditions (Ding et al, 1995).…”

Spatiotemporal variations of Chinese lakes and their driving mechanisms since the Last Glacial Maximum: A review and synthesis of lacustrine sediment archives

“…Currently, the growth and decline of the winter and summer monsoon has caused drying conditions associated with the development of closed salt lakes and brine lakes in western China, while climates in eastern and southern China are normally warm and wet, resulting in open and outflowing lakes. The Asian monsoon, as one of the important sub-systems of the global climate [66], is closely related to changes in insolation [67,68] and global ice volume [69][70][71] on 10 4 a time scales. On 10 4 -10 3 a time scales, the lake evolution is not only affected by the land-atmosphere interactions of the high latitudes, but also by the ocean-atmosphere interactions of the low latitudes.…”

High Arabian Sea productivity conditions during MIS 13 – odd monsoon event or intensified overturning circulation at the end of the Mid-Pleistocene transition?

“…The Chinese loess plateau (CLP) is considered another important climate archive for the reconstruction of the Asian summer and winter monsoon as far back as 22 million years ago (Ding et al, 1995;Guo et al, 2002;Kukla et al, 1988;Porter and An, 1995). The winter monsoon transports dust from the Asian inlands to the CLP, while the summer monsoon brings precipitation (Porter and An, 1995).…”

“…magnetic susceptibility) reflect the degree of chemical weathering and, thus, soil formation (Liu and Ding, 1998). Many loess records are dominated by glacial-interglacial variability superimposed by millennial scale events, which correlate to Heinrich events (Ding et al, 1995;Liu and Ding, 1998;Porter and An, 1995).…”