Westerlies Asia and monsoonal Asia: Spatiotemporal differences in climate change and possible mechanisms on decadal to sub-orbital timescales

Abstract The ‘westerlies-dominated climatic regime’ (WDCR) in the present interglacial period was proposed because precipitation/moisture variations between arid central Asia and mid-latitude monsoonal Asia are out-of-phase or anti-phased on different timescales during the Holocene. In this study. we first review the development of the theoretical framework of the WDCR, and then outline the boundary of its core area: from the Caspian Sea in the west to the western Hexi Corridor in the east, with the northern and southern limits coinciding with the domain of arid central Asia. Next, we present a synthesis of multiple lines of evidence for the occurrence of the WDCR on multi-millennial (‘sub-orbital’ herein) to decadal timescales during the Holocene. Finally, we examine the possible physical mechanisms responsible for the WDCR. We find that external factors (insolation changes induced by orbital factors) generated the WDCR on a sub-orbital timescale, whereas a circum-global teleconnection/Silk Road pattern was the most significant factor responsible for the WDCR on centennial and decadal timescales. The study provides a comprehensive summary of the development of our knowledge of the WDCR over the past several decades, together with a tentative theoretical framework for understanding climatic and environmental changes within its region of influence. In addition, it forms a scientific basis for environmental management and ecological restoration in this arid region in the context of global warming.