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关于上新世阶段青藏高原北部是否存在显著隆升事件这一问题目前依然存在较大的争议。本研究尝试利用沙尘气候模拟方法对上新世高原隆升的可能性做一评估。北太平洋风尘记录显示亚洲内陆干旱化在三到四百万年存在非常显著的增强,这可能是由于全球气候变冷和/或青藏高原隆升引起的。基于此,我们利用一个耦合了沙尘模块的气候模式,通过一系列敏感性试验测试大气沙尘沉积通量对于上新世以来主要气候强迫,包括冰盖变化,海表温度,大气二氧化碳浓度和青藏高原北部地形的响应。可能引起粉尘通量变化的大气环流和沙尘源区面积两个因素的改变在试验中都被考虑。模拟结果表明,冰盖扩张、海表温度下降和大气二氧化碳浓度下降这些全球变冷因素仅能解释中上新世和末次盛冰期北太地区粉尘沉积通量改变量的约三分之二,而剩下的三分之一需要归因于青藏高原北部的隆升。高原北部的隆升可以显著恶化内陆干旱状况从而提升大气粉尘浓度,支持了上新世高原北部存在明显隆升事件这一观点。
There is still much controversy over the existence of a significant upturn in the northern part of the Qinghai-Tibet Plateau during the Pliocene period. This study attempts to use sand and dust climate modeling method to evaluate the possibility of uplift of the Pliocene. North Pacific dust records show a very significant increase of inland aridification in Asia between 3-4 million years, possibly due to the global climate change and / or the uplift of the Qinghai-Tibet Plateau. Based on this, we use a climatic model coupled with a sand-dust module to test atmospheric dust deposition fluxes through a series of sensitivity tests for the major climatic forcing since the Pliocene, including changes in ice cover, sea surface temperature, atmospheric carbon dioxide concentration and Response of the Northern Tibetan Plateau to the Terrain. Changes in both atmospheric circulation and dust source area that could cause changes in dust flux were considered in the experiments. The simulation results show that the global cooling factors such as the expansion of ice sheet, the decrease of sea surface temperature and the decrease of atmospheric carbon dioxide concentration can only explain about two-thirds of the change in dust deposition fluxes in the Middle Pliocene and the North Pacific over the last glacial-ice age. The remaining one third is due to the uplift of the northern Tibetan Plateau. Uplift in the northern plateau can significantly worsen the inland arid conditions and thus increase atmospheric dust concentrations, supporting the notion that there was a clear uplift in northern Pliocene.