Westerly jet‐East Asian summer monsoon connection during the Holocene

Abstract

The causes of spatial and temporal changes in East Asian summer monsoon (EASM) precipitation on millennial to multimillennial time scales during the Holocene have not yet been resolved. Here, we examine the relationship between spatial variations in EASM precipitation and the westerly jet (WJ) path over East Asia during the Holocene using the provenance of eolian dust in Japan Sea sediments, which we interpret to reflect changes of the WJ path over East Asia and/or surface conditions of desert areas. The contribution of dust from the Mongolian Gobi Desert relative to that from the Taklimakan Desert shows millennial‐scale to multimillennial‐scale minima at 11.5–10, 7–5, and 3.5–1.5 kyr B.P., which we attribute to earlier seasonal northward progression of the WJ. These dates correlate with precipitation maxima along the present northwestern EASM margin and minima in eastern Northeast China and the Yangtze River Basin, suggesting that the WJ shifted northward earlier in the year, allowing earlier northward migration of the EASM rainband and generating abundant precipitation in the northwestern EASM margin. Therefore, during the Holocene, changes of the WJ path probably contributed to the millennial‐scale to multimillennial‐scale EASM precipitation changes and its northwest‐southeast contrast within China. Our findings suggest that WJ path changes are critical to understand the dynamics of EASM in the past, present, and future.