Variability of summer humidity during the past 800 years on the eastern Tibetan Plateau inferred from δ 18 O of tree-ring cellulose
Variability of summer humidity during the past 800 years on the eastern Tibetan Plateau inferred from δ 18 O of tree-ring cellulose
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DOI：
10.5194/cp-11-327-2015
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发表时间：
2015-02
影响因子：
4.3
通讯作者：
Jakob Wernicke;Jussi Grießinger;P. Hochreuther;A. Bräuning
中科院分区：
文献类型：
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作者：
Jakob Wernicke;Jussi Grießinger;P. Hochreuther;A. Bräuning
抽象的。本文报道了青藏高原东部800年的δ18O年代学。该年表可追溯到公元1193年，并于公元1996年从活的西藏杜松树中取样。这是西藏东部地区第一个基于树木年轮的长期δ 18 O年代学，为水文气候重建提供了可靠的档案。在夏季与水文气候变量（相对湿度，水汽压和降水）的高度显着的相关性。我们应用线性传输模型来重建夏季相对湿度的变化在过去的800年。在中世纪温暖期结束时，更潮湿的条件占了上风，而在小冰河时期的系统性转变是不可检测的。自19世纪70年代以来，一个明显的趋势是更加干燥的条件。湿度下降在1950年代前后有所减弱，但仍呈负趋势。世纪中期的湿度下降与藏南地区的多代理水文气候重建相一致。而夏季相对湿度下降的趋势在TP的中东部更为明显。此外，我们研究地点的相对湿度与TP大部分地区的相对湿度显著相关。因此，我们推断，重建的相对湿度主要是由本地和中尺度气候驱动器控制，虽然观察到的显着连接到亚洲中西部的对流层较高。
Abstract. We present an 800-year δ18O chronology from the eastern part of the Tibetan Plateau (TP). The chronology dates back to AD 1193 and was sampled in AD 1996 from living Juniperus tibetica trees. This first long-term tree-ring-based δ18O chronology for eastern Tibet provides a reliable archive for hydroclimatic reconstructions. Highly significant correlations were obtained with hydroclimatic variables (relative humidity, vapour pressure, and precipitation) during the summer season. We applied a linear transfer model to reconstruct summer season relative humidity variations over the past 800 years. More moist conditions prevailed during the termination of the Medieval Warm Period while a systematic shift during the Little Ice Age is not detectable. A distinct trend towards more dry conditions since the 1870s is apparent. The moisture decline weakened around the 1950s but still shows a negative trend. The mid-19th century humidity decrease is in good accordance with several multiproxy hydroclimate reconstructions for south Tibet. However, the pronounced summer relative humidity decline is stronger on the central and eastern TP. Furthermore, the relative humidity at our study site is significantly linked to the relative humidity at large parts of the TP. Therefore, we deduce that the reconstructed relative humidity is mostly controlled by local and mesoscale climatic drivers, although significant connections to the higher troposphere of west-central Asia were observed.