Orbital to millennial scale dust activity and humidity interaction in Central Asia during the last glacial period

Abstract

The factors controlling dust activity and humidity in Central Asia and their relationships remain controversial, partly due to a lack of high-resolution geological records for the mid-to-late last glaciation. In this study, we established an optically stimulated luminescence chronology for the QSHA profile in the Yili Basin, a region influenced by westerlies. Grain size and trace element data were used as paleoclimatic indicators. We investigated the relationships among Central Asian dust activity, humidity, and westerlies strength on orbital to millennial scale from 37.4 ka to 11.6 ka. Our study reveals that, on orbital timescales, humidity is positively correlated with westerlies strength which controlled by precession. Dust activity is controlled by Siberian High which was regulated by Northern Hemisphere high-latitude temperature. Their responses to low-latitude and high-latitude forcing mechanisms respectively and present an opposite relationship. On millennial timescales, humidity and westerlies strength are positively correlated. During Marine Isotope Stage (MIS) 2, humidity and dust activity show synchronous fluctuations, while during MIS 3, they exhibit an inverse relationship. Westerlies strength regulated humidity, which subsequently controlled glacial activity in the Tianshan Mountains, influencing dust activity in Central Asia. Additionally, the QSHA profile recorded seven Dansgaard-Oeschger (D-O) events on millennial timescales, indicating a potential link between Central Asian dust activity and high-latitude temperature variations in the Northern Hemisphere. Our findings provide new insights into dust and humidity interaction during the last glaciation periods in Central Asia and contribute to understanding global dust and hydrological cycles.