Correlation and anti-correlation of the Asian summer monsoon and westerlies during the Holocene

Abstract The relationship between the Asian summer monsoon (ASM) and westerlies at different timescales is still under discussion. In this paper, we present Holocene precipitation records derived from loess and lake sediment in the northeastern Tibetan Plateau and reconstruct changes in the strength of the ASM during the Holocene. Compared with other Eurasian paleohydroclimatic records, we find that precipitation variations between ASM- and westerlies-dominant regions are positively correlated (anti-correlated) at millennial (sub-orbital) timescales. Based on the analysis of the TraCE-21 results, we suggest that Atlantic meridional overturning circulation may be the primary reason for this in-phase pattern at millennial timescales whereas this anti-phased pattern at sub-orbital timescales is attributed to precessional changes. Due to different response mechanisms, the relationship between the ASM and westerlies may differ significantly at different timescales, which highlights the complex dynamic characteristics of atmospheric systems in the Northern Hemisphere and the challenges for future predictions.