The Qaidam Basin marks a crucial boundary between the Westerlies and the Asian summer monsoons. Previous studies in the Qaidam Basin have advanced our knowledge of the paleoclimate over glacial to interglacial cycles. However, our understanding of the paleoclimatic sensitivity of the Qaidam Basin to the relative strength of these two climatic driving forces remains limited due to the lack of regional paleoclimatic reconstructions. The Qaidam Basin is proposed as a regional and global eolian dust source during the glacial periods, during which a cold, dry climate is associated with the equatorward shift of the jet stream. On the contrary, paleoshoreline records suggest that a highstand lake stage prevailed in late Marine Isotope Stage 3 (MIS 3) and lasted until 15 ka. To address this conundrum, we have applied an integrated approach to reconstructing the regional paleoclimatic history by combining compound-specific isotope analysis, lake temperature reconstruction, and numerical modeling. Our results show varying paleoclimate associated with the dynamic climate boundary since 45 ka: (1) a wet climate during late MIS 3, when the Asian summer monsoons are strengthened under high summer insolation and penetrate further into Central Asia; (2) a general cold, dry but wetter than at present climate in the Last Glacial Maximum (LGM), when the Asian summer monsoons retreat and the Westerlies become dominant; and (3) three short periods of extreme aridity corresponding to the Younger Dryas and Heinrich 2 and 4 events, when the normal moisture transport via the Westerlies and Asian summer monsoons is interrupted. The numerical modeling supports an increase in the effective precipitation during the LGM due to reduced evaporation under low summer insolation. These results suggest that the Westerlies and Asian summer monsoons alternately controlled the climate in the Qaidam Basin in response to precessional forcing during the late Pleistocene.

中文翻译：

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自 45 ka 以来西风带和亚洲夏季风之间的相互作用剖面图：柴达木盆地生物标志物、同位素和数值模拟研究的见解

柴达木盆地是西风带和亚洲夏季风的重要分界线。先前在柴达木盆地的研究提高了我们对冰期到间冰期循环古气候的认识。然而，由于缺乏区域古气候重建，我们对柴达木盆地古气候敏感性对这两种气候驱动力的相对强度的了解仍然有限。柴达木盆地被认为是冰川时期的区域性和全球风尘源，在此期间，寒冷干燥的气候与急流向赤道移动有关。相反，古海岸线记录表明，海洋同位素第 3 阶段（MIS 3）晚期盛行高位湖泊阶段，并持续到 15 ka。为了解决这个难题，通过结合特定化合物的同位素分析、湖泊温度重建和数值模拟，我们采用了一种综合方法来重建区域古气候历史。我们的研究结果表明，自 45 ka 以来，与动态气候边界相关的古气候发生了变化：（1）MIS 3 晚期的潮湿气候，当时亚洲夏季风在夏季高日照下加强并进一步渗透到中亚；(2) 末次盛冰期（LGM）气候普遍寒冷、干燥但比现在湿润，亚洲夏季风消退，西风带占主导地位；(3) 三个短时期的极端干旱，对应于 Younger Dryas 和 Heinrich 2 和 4 事件，此时通过西风和亚洲夏季风的正常水分输送被中断。由于夏季低日照条件下蒸发减少，数值模拟支持 LGM 期间有效降水的增加。这些结果表明，西风和亚洲夏季风交替控制柴达木盆地的气候，以响应晚更新世的岁差强迫。