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Variations in the oxygen isotopic composition of precipitation in the Tianshan Mountains region and their significance for the westerly circulation

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Journal of Geographical Sciences 2015年第7期25卷 801-816页

作者：刘小康饶志国张肖剑黄伟陈建徽陈发虎 Key Laboratory of Western China's Environmental Systems (Ministry of Education) Lanzhou University

Proxy records of the oxygen isotopic composition of meteorological precipitation （δ^18Op） preserved in archives such as ice cores, lacustrine carbonates and stalagmite calcite are important for paleoclimatic studies. Therefore, knowledge of the variations and controlling mechanisms of modern δ^18Op on different time scales is necessary. Here, we investigate the linear correlations between δ^18Op and corresponding temperature and precipitation on monthly and inter-annual timescales, using data from the Urumqi （1986-2003） and Hotan stations of the Global Network of Isotopes in Precipitation （GNIP）, and δ^18O data from 4 ice cores in the adjacent Tianshan Mountains. Consistent with previous reported results, modern δ^18Op variations on a seasonal time scale in the Tianshan region are mainly controlled by a ＇temperature effect＇（indicated by a significant positive correlation between δ^18Op and temperature）, with more positive δ^18Op values occurring in summer. However, on an inter-annual timescale, there is a weak inverse correlation between weighted average annual δ^18Op and annual average temperature at Urumqi station. This finding is supported by the inversely varying trends of δ^18Op data from 4 ice cores in the central and eastern Tianshan Mountains compared to annual average temperatures in the same region during the past 40-50 years. The data from Urumqi station and the 4 ice cores demonstrate that there is inverse correlation between δ^18Op and temperature on inter-annual to decadal time scales. Analysis of water vapor sources and pathways for the warm year of 1997 and the cold year of 1988 reveal that relatively more water vapor for the Tianshan region was derived from long-distance transport from high-latitude sources than during the warm year of 1997; and that more water vapor was transported from more proximal sources from mid- to low-latitude areas during the cold year of 1988. In addition, the δ^18Op values are more negative in the high latitude areas tha

关键词： Tianshan Mountains Urumqi δ^18Op water vapor sources westerly circulation

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Relationship between the rise and fall of Loulan ancient city and centennial-scale climate events and cycles

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Frontiers of Earth Science 2023年第4期17卷 1070-1080页

作者： Deke XU Chang LI Yingyu JIN Zhenhua DENG Bing XU Kangkang LI Jianping ZHANG Xiaohong SUN Jing FENG Yingxin JIAO Hao LI Xiaoguang QIN Key Laboratory of Cenozoic Geology and Environment Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China Institute of Earth Science Chinese Academy of SciencesBeijing 100029China School of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China Beijing Jianhua Experimental Yizhuang School Beijing 100176China School of Archaeology and Museology Peking UniversityBeijing 100871China Geological Research Institute of China Chemical Geology and Mine Bureau Beijing 100013China Loulan Museum of Ruoqiang County Bayingol Mongolian Autonomous PrefectureXinjiang 841800China

The discovery of Loulan ancient city(LA)in the early 20th century has important significance for understanding the history of Western regions and the Silk Road *** current academic community still has disputes on whether LA was the capital of Loulan Kingdom,the time of its rise,peak and decline,and the process,rate and driving mechanism of human activity *** study uses the radio carbon dates(^(14)C)database of LA to reconstruct the history of the rise and fall of human activity,and finds that LA experienced more than~500 years from its rise to its peak and then to its decline:1)the city rose rapidly,and the population increased rapidly from~A.D.0 to 230;2)the city was prosperous and flourishing,and the intensity of human activity reached its peak from~A.D.160 to 340,especially in~A.D.230,when the population reached its peak;3)the city accelerated its decline,and the intensity of human activity decreased significantly,and the population shrank rapidly from~A.D.230 to 500;4)LA was completely abandoned after~*** results of the ^(14)C dating database do not support that LA was the early capital of the Loulan *** comparing the human activity record of LA with the existing high-resolution palaeoclimate records in the surrounding mountainous areas of the Tarim Basin and South Asia,it is found that the superposition of centennial-scale westerly circulation strength events and the~500-year cycle of the Indian monsoon jointly controlled the precipitation and meltwater(snow)supply of the mountains in the Tarim Basin,affecting the changes of surface runoff and oasis area in the basin,which is one of the important factors causing the rise and fall of LA.

关键词： ^(14)C probability density time series analysis ~500-year cycle Indian monsoon westerly circulation

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