Modeling Impacts Of The Tibetan Plateau Uplift On The Climate During The Middle Eocene(40Ma)

The researches on the history and the uplift process of the Tibetan Plateau(TP) are mostly accomplished by fossil, sedimentology, sequence stratigraphy and paleo magnetic method. And the latest study has been made to show that the central TP was elevated by 40 Ma ago. As one of the most important geological events in Cenozoic era, the uplift of the TP has had profound influences on the Asian and global climate and environment evolution(LIU Xiao Dong, 2013). However, how the uplift of the TP affects the global climate under the condition of greenhouse climate remains unclear. How does the uplift of the TP impact the East Asia and global climate during the middle Eocene(40Ma) and what kind of role would the uplift of the TP play in the Eocene global cooling during the geological history? Whether can we determine the uplift process of the TP from the perspective of climate change? In order to explore the underlying physical processes and mechanisms, a fully coupled model, Community Earth System Model(CESM), were used in this paper. Two experiments were designed. They were run with and without the uplift model of the Proto-TP, respectively(referred to as PTP, NTP experiments). We analyzed the numerical experiment results and compared them with the geological data. The results are as follows.1) As a result of the uplift of the Proto-TP, the subtropical highs enhanced which can reinforce the Hadley circulation. As a consequence, the precipitation decreases at most areas of middle latitude. But East Asian rainfall increased with the emergence of the Proto-TP.2) Numerical experiments show that the modern Asian monsoon has been formed and widely distributed in eastern and southern Asia in the middle Eocene(40Ma), which is consistent with Quan’s views. The uplift of the Proto-TP enhances East Asian monsoon and the region of the East Asian monsoon continue to expand to the north.3) Compared with the ancient temperature data of the China area, it is found that numerical test(PTP) simulation results are more consistent with the geological record data, which can infer that there has been the Proto-TP in the middle Eocene.4) The uplift of the Proto-TP leads to small warming in the low latitude region. The temperature of Arctic region and Antarctica cools by as much as 0.8 degree Celsius, which increases the temperature gradient of the equator to the poles. This is meaningful that the uplift of Proto-TP may be a forcing to accelerate the Cenozoic global cooling during the geological history.