Abstract
Abstract. The orbital-timescale dynamics of the Quaternary Asian summer monsoons (ASM) are frequently attributed to precession-dominated northern hemispheric summer insolation. However, this long-term continuous ASM variability is inferred primarily from oxygen isotope records of stalagmites, mainly from Sanbao cave in mainland China, and may not provide a comprehensive picture of ASM evolution. A new spliced stalagmite oxygen isotope record from Yangkou cave tracks summer monsoon precipitation variation from 124 to 206 thousand years ago in Chongqing, southwest China. Our Yangkou record supports that the evolution of ASM was dominated by the North Hemisphere solar insolation on orbital timescales. When superimposed on the Sanbao record, the precipitation time series referred from Yangkou cave stalagmites supports the strong ASM periods at marine isotope stages (MIS) 6.3, 6.5, and 7.1 and weak ASM intervals at MIS 6.2, 6.4, and 7.0. This consistency confirms that ASM events affected most of mainland China. Except for the solar insolation forcing, the large amplitude of minimum δ18O values in Yangkou record during glacial period, such as MIS 6.5, could stem from the enhanced prevailing Pacific trade wind and/or continental shelf exposure in the Indo–Pacific warm pool.
Highlights
Climate in East Asia, the most densely populated region in the world, is profoundly influenced by the Asian monsoon (AM), which includes the Indian monsoon and East Asian monsoon sub-systems
Stalagmite-inferred orbital-scale Asian summer monsoon (ASM) intensity closely follows the change in precession-dominated northern hemispheric (NH) summer insolation (NHSI) (Wang et al, 2008; Cheng et al, 2012b)
One to two hiatuses are observed for stalagmites YK12, YK23, and YK61 (Figs. 2, 3)
Summary
Climate in East Asia, the most densely populated region in the world, is profoundly influenced by the Asian monsoon (AM), which includes the Indian monsoon and East Asian monsoon sub-systems. Stalagmite-inferred orbital-scale ASM intensity closely follows the change in precession-dominated northern hemispheric (NH) summer insolation (NHSI) (Wang et al, 2008; Cheng et al, 2012b). These 100s kyr records were mainly from a single cave, namely Sanbao cave, located in Hubei Province, China (Fig. 1; Wang et al, 2008; Cheng et al, 2012b). These uncertainties stem from differences in local or regional climatic and environmental conditions (Lachniet, 2009), hydrological variability
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