新生代青藏高原形成与全球温度变化对东亚气候影响的对比研究

The formation of the Tibetan Plateau (TP) and the change of global temperature are two important factors affecting the East Asian climate change during the Cenozoic. Up to now, there are still debates about each climate effect and more studies focusing on the climate effects of two factors on the East Asia during the Cenozoic are needed. On the one hand, previous numerical studies about the formation of the TP remain simplified in design, in that they only considered the TP uplift based on its present position, whereas in fact the TP once located in the south of its present position. However, the impact of the northward movement of the TP on the East Asian climate remains unclear. On the other hand, the change of global temperature also has significant effects on the East Asian climate, but the effects of corresponding processes in high and low latitudes on the East Asian climate in different geological periods are still unclear. This project is expected to use Community Earth System Model version 1.2 to conduct several sets of experiments to compare the climate effect of the formation of the TP and the change of global temperature on the East Asian climate change during the Cenozoic. This project will promote deeply understanding of the process of the East Asian climate evolution and corresponding mechanisms.

青藏高原形成和全球温度变化是影响新生代东亚气候演变的重要强迫因子，但目前对两者作用还存在争议，仍需开展新生代不同地质时期两者气候效应的对比研究。一方面，以往研究多关注青藏高原位于现代位置且主要强调高原高度增加所带来的气候影响，而实际上高原曾经比现在靠南，且之后出现向北移动，但这个向北移动过程导致的气候效应尚不明确；另一方面，全球温度变化在驱动东亚气候变化方面也具有显著作用。但在不同地质时期，全球温度变化如何通过高纬过程（海冰、温盐环流等）和低纬过程（赤道辐合带、厄尔尼诺等）来影响东亚气候还不清楚。本项目拟利用地球系统模式CESM1.2构建数值试验，集中研究新生代青藏高原形成和全球温度变化对东亚气候演变的分别影响及差异。本项目的开展有望揭示不同纬度青藏高原影响东亚气候的动力机制、不同地质时期东亚气候变化与高、低纬过程间的联系，并为深入认识新生代东亚气候演变历史提供理论参考。

青藏高原形成和全球温度变化是影响新生代东亚气候演变的重要强迫因子，但目前对两者作用还存在争议。本项目开展了一系列数值模拟试验研究了两者对东亚气候的影响，结果表明：1.青藏高原北移是新生代东亚气候演化的重要因子。青藏高原北移会增加中国东部降水并增强亚洲内陆干旱，并且，随高原纬度变化的东亚气候呈现非均一变化；2.全球变冷过程，包括大气CO2含量的降低以及南极冰盖的发展，可显著增强中国东部降水与风场的季节性，从而有助于中国东部类似现代季风气候的形成；3.青藏高原隆升可显著增加早中新世中国东部的年降水，而全球变冷会减少中国东部的降水；4.全球变冷可加强亚洲内陆干旱化，但对干旱区的北移影响较小，而青藏高原隆升可使得亚洲内陆干旱区北移并且干旱程度加强。本项目研究成果揭示了新生代青藏高原形成与全球温度变化对东亚季风气候和亚洲内陆干旱环境演化的差异影响，促进了对新生代东亚气候演变历史的深入理解。