The mid-latitude Westerlies and the East Asian winter monsoon (EAWM) are two major atmospheric circulation systems influencing dust activities in the Northern Hemisphere (NH). However, the interplay between these wind systems and their effects on regional dust activities remain poorly understood. In this study, we present a well-dated aeolian sedimentary sequence from the loess section (ZES) on the southern slope of the Qilian Mountains in the northeastern Qinghai-Tibetan Plateau (NE-QTP). It provides insights into the response of dust activities to these wind systems for the last 18.5 ka. We developed a detailed chronology for ZES section based on luminescence dating of multiple signals from 29 samples (yielding a total of 87 ages). The luminescence sensitivities and element analysis of the sediments indicate a shift in dust source around 7.5 ka, contributed to a transition in the atmospheric circulation controls of the NE-QTP. Specially, our findings suggest that dust activity was likely dominated by EAWM from 18.5 ka to 7.5 ka and by the Westerlies after 7.5 ka across this area. We propose that increased NH ice volume (NHIV) significantly enhanced the EAWM via strengthening Siberian High, driving dust activities over the high mountains during the Last Deglaciation and Early Holocene. In contrast, as NHIV decreased during the middle-to-late Holocene, the EAWM weakened and retreated from this area, allowing the Westerlies to dominate dust activities. Additionally, grain-size parameters of sediments were used to infer variations in the intensities of these winds, revealing a gradual weakening of EAWM since the Last Deglaciation and a marked intensification of the Westerlies during the warm middle Holocene. Under the current global warming scenario, we predict that the Westerlies will continue to dominate dust activities across the NE-QTP, with a potential increase in dust activities if the Westerlies enhance.

中文翻译：

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18.5 ka 以来，西风和东亚冬季风交替主导青藏高原东北部的沙尘活动


中纬度西风和东亚冬季风 （EAWM） 是影响北半球 （NH） 尘埃活动的两个主要大气环流系统。然而，这些风系统之间的相互作用及其对区域沙尘活动的影响仍然知之甚少。在这项研究中，我们提出了来自青藏高原东北部祁连山脉南坡黄土剖面 （ZES） 的年代明确的风积沉积序列 （NE-QTP）。它提供了对过去 18.5 ka 中沙尘活动对这些风系统的响应的见解。我们根据来自 29 个样本的多个信号的发光测年（总共产生 87 个年龄）开发了 ZES 切片的详细年表。沉积物的发光敏感性和元素分析表明，尘埃源在 7.5 ka 附近发生偏移，有助于 NE-QTP 大气环流控制的转变。特别是，我们的研究结果表明，该地区的沙尘活动可能由 EAWM 在 18.5 ka 到 7.5 ka 之间和在 7.5 ka 之后的 Westerlies 主导。我们提出，NH 冰量 （NHIV） 的增加通过加强西伯利亚高地，在末次冰川消融和全新世早期推动高山上的尘埃活动，显着增强了 EAWM。相比之下，随着全新世中晚期 NHIV 的减少，EAWM 减弱并从该地区撤退，使 Westerlies 主导了尘埃活动。此外，沉积物的粒度参数用于推断这些风强度的变化，揭示了自最后一次冰川消融以来 EAWM 逐渐减弱，并在温暖的全新世中期期间西风显着增强。 在当前的全球变暖情景下，我们预测西风层将继续主导整个 NE-QTP 的沙尘活动，如果西风带增强，沙尘活动可能会增加。