Co-evolution of orbital-to-millennial East Asian monsoon and westerlies variability over the past 150 ka

Abstract

Understanding the evolution and interaction of the mid-latitude westerlies and East Asian monsoon (EAM) is crucial for comprehending Asian climate dynamics. While abundant evidence from loess, lake and speleothem records in arid Central Asia (ACA) and East Asia has revealed the interplay between the mid-latitude westerlies and the EAM on orbital and millennial scales, most of these records only cover the period since the last glacial maximum. Thus, the trade-off relationship between the mid-latitude westerlies and the EAM on glacial-interglacial to millennial timescale since the last interglacial period remains unclear. In this study, we present 150 ka-long grain-size and organic carbon records from two loess sections in the western Chinese Loess Plateau (CLP) and Yili Basin to assess the wind intensity and moisture variability between East Asia and ACA at glacial-interglacial to millennial timescales. Our results indicate that the East Asian winter monsoon (EAWM) and westerly wind exhibit synchronous glacial-interglacial and precession-scale fluctuations. However, the moisture exhibits consistent variations between East Asia and ACA on glacial-interglacial timescale, whereas inconsistent pattern at precessional timescale. The moisture variations in ACA lagged those in the East Asia by 2 kyr during marine isotope stages (MIS)5. Millennial-scale wind and moisture variability in East Asia and ACA are broadly correlated with cooling events in the North Atlantic. Based on the modeling results of the TraCE-21 ka, we suggest that the wind and moisture variations in East Asia and ACA are controlled by the combined effects of ice sheets, insolation, and meltwater flux from orbital to millennial timescales. Therefore, our study provides new insights into the complex interplay between the EAM and mid-latitude westerlies, which can contribute to a better understanding of Asian climate dynamics.