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	Drought variability at the northern fringe of the Asian summer monsoon region over the past millennia
	Zhao Y.; Zhao Y.
	2014
关键词	Tree rings Drought Palmer drought severity index The Asian summer monsoon Past climate change Regional climate dynamics low-frequency variability pacific sst variability last 2 millennia tree-ring temperature variability hemisphere temperature atlantic oscillation tibetan plateau severity index central china
英文摘要	The northern fringe of the Asian summer monsoon region (NASM) in China refers to the most northwestern extent of the Asian summer monsoon. Understanding the characteristics and underlying mechanisms of drought variability at long and short time-scales in the NASM region is of great importance, because present and future water shortages are of great concern. Here, we used newly developed and existing tree-ring, historical documentary and instrumental data available for the region to identify spatial and temporal patterns, and possible mechanisms of drought variability, over the past two millennia. We found that drought variations were roughly consistent in the western (the Qilian Mountains and Hexi Corridor) and eastern (the Great Bend of the Yellow River, referred to as GBYR) parts of the NASM on decadal to centennial timescales. We also identified the spatial extent of typical multi-decadal GBYR drought events based on historical dryness/wetness data and the Monsoon Asia Drought Atlas. It was found that the two periods of drought, in AD 1625-1644 and 1975-1999, exhibited similar patterns: specifically, a wet west and a dry east in the NASM. Spatial characteristics of wetness and dryness were also broadly similar over these two periods, such that when drought occurred in the Karakoram Mountains, western Tianshan Mountains, the Pamirs, Mongolia, most of East Asia, the eastern Himalayas and Southeast Asia, a wet climate dominated in most parts of the Indian subcontinent. We suggest that the warm temperature anomalies in the tropical Pacific might have been mainly responsible for the recent 1975-1999 drought. Possible causes of the drought of 1625-1644 were the combined effects of the weakened Asian summer monsoon and an associated southward shift of the Pacific Intertropical Convergence Zone. These changes occurred due to a combination of Tibetan Plateau cooling together with more general Northern Hemisphere cooling, rather than being solely due to changes in the sea surface temperature of the tropical Pacific. Our results provide a benchmark for comparing and validating paleo-simulations from general circulation model of the variability of the Asian summer monsoon at decadal to centennial timescales.
出处	Climate Dynamics
卷	43
期	3-4
页	845-859
收录类别	SCI
语种	英语
ISSN号	0930-7575
内容类型	SCI/SSCI论文
源URL	[http://ir.igsnrr.ac.cn/handle/311030/29473]
专题	地理科学与资源研究所_历年回溯文献
推荐引用方式 GB/T 7714	Zhao Y.,Zhao Y.. Drought variability at the northern fringe of the Asian summer monsoon region over the past millennia. 2014.

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