The Inner Tibetan Plateau (ITP), the central and western part of the Tibetan Plateau (TP), covers about one-fourth of the entire TP and contains more than 800 endorheic lakes larger than 1 km2. These lakes are important water reservoirs and sensitive to TP climate changes. They regulate regional water circulations, and further influence local ecosystems. Many lakes in ITP are surrounded by conspicuous paleoshorelines indicating much higher past lake levels. Previous studies found that lakes in the western ITP (west of ~86o E) apparently expanded to higher levels than those to the east during the Holocene high lake level stage, however, there is no in-depth study on the reasons for the spatial differences of high lake levels within the ITP. In this study, we first identify Holocene lake level (or lake extent) changes over the ITP by combining published lake level variation data with our reconstruction of Dagze Co lake level variations. We then investigate spatial differences in the magnitude of lake expansions and explore the underlying forces driving these differences using the transient climate evolution of the last 21 ka (TraCE-21ka) and Kiel Climate Model (KCM) simulation results. We find that lakes in the ITP expanded to their highest levels during the early Holocene when the Indian summer monsoon (ISM) greatly intensified. After the mid-Holocene, lake levels fell as a result of the weakening of the ISM. The early Holocene northward shift of the westerly jet and a positive phase of the Atlantic multidecadal oscillation (AMO) resulted in the intensification of southwesterly winds on the southwest TP flank. Concurrently, westerly winds over the TP weakened, causing a differential increase in water vapor transport to the ITP with higher precipitation levels in the southwestern ITP and lower levels to the northeast. These wind-driven differential precipitation levels caused lakes in the southwestern ITP to expand to higher levels than those in the central, northern and northeastern ITP. During the early Holocene, expansion of lakes in the northwestern ITP was enhanced by an increase in glacier melt water besides the increased summer rainfall associated with the intensified ISM.

中文翻译：

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全新世青藏高原内陆湖泊时空变化的驱动力

青藏高原内陆（ITP）是青藏高原（TP）的中部和西部，约占整个青藏高原的四分之一，包含 800 多个大于 1 平方公里的内陆湖泊。这些湖泊是重要的水库，对青藏高原气候变化敏感。它们调节区域水循环，并进一步影响当地生态系统。ITP 中的许多湖泊都被显眼的古海岸线包围，表明过去的湖泊水位要高得多。以往的研究发现，在全新世高湖水位阶段，ITP西部（~86o E以西）的湖泊明显扩大到高于东部的湖泊，但对空间差异的原因没有深入研究ITP 内的高湖水位。在这项研究中，我们首先通过将已发布的湖泊水位变化数据与我们对 Dagze Co 湖水位变化的重建相结合，确定 ITP 上全新世湖泊水位（或湖泊范围）的变化。然后，我们研究了湖泊扩张幅度的空间差异，并使用最近 21 ka (TraCE-21ka) 和基尔气候模型 (KCM) 模拟结果的瞬态气候演变来探索驱动这些差异的潜在力量。我们发现，当印度夏季风 (ISM) 大大增强时，ITP 中的湖泊在全新世早期扩张至最高水平。在全新世中期之后，由于 ISM 减弱，湖泊水位下降。全新世早期西风急流北移和大西洋年代际振荡（AMO）的正相位导致高原西南侧西南风增强。同时，高原上的西风减弱，导致向 ITP 输送的水汽差异增加，ITP 西南部的降水量较高，而东北部的降水量较低。这些风力驱动的差异降水水平导致 ITP 西南部的湖泊扩大到高于 ITP 中部、北部和东北部的湖泊水平。在全新世早期，除了与 ISM 加剧相关的夏季降雨量增加之外，ITP 西北部湖泊的扩张还因冰川融水的增加而增强。导致 ITP 西南部降水量较高，而东北部降水量较低，导致向 ITP 输送的水汽差异增加。这些风力驱动的差异降水水平导致 ITP 西南部的湖泊扩大到高于 ITP 中部、北部和东北部的湖泊水平。在全新世早期，除了与 ISM 加剧相关的夏季降雨量增加之外，ITP 西北部湖泊的扩张还因冰川融水的增加而增强。导致 ITP 西南部降水量较高，而东北部降水量较低，导致向 ITP 输送的水汽差异增加。这些风力驱动的差异降水水平导致 ITP 西南部的湖泊扩大到高于 ITP 中部、北部和东北部的湖泊水平。在全新世早期，除了与 ISM 加剧相关的夏季降雨量增加之外，ITP 西北部湖泊的扩张还因冰川融水的增加而增强。