The tree-ring cores of Tianshan spruces collected from nine sites in the Urumqi River drainage of the middle Tianshan Mountains were used to establish three types of the tree-ring width chronologies over the last 370 ...The tree-ring cores of Tianshan spruces collected from nine sites in the Urumqi River drainage of the middle Tianshan Mountains were used to establish three types of the tree-ring width chronologies over the last 370 years, using the international standard method of dendrochronology. Our study demonstrates that dendrochronology can be better used to reconstruct the number of the precipitation day than to reconstruct the precipitation amount in middle Tianshan Mountains. It is found that the residual chronology among the three tree-ring width chronologies has the best relationship with number of spring precipitation days from May 20 to June 8. The chronologies at Haxionggou B site and Zaierdegou site in the Urumiqi drainage have the highest correlation with the observed number of spring precipitation days at Daxigou meteorological station, and are used to reconstruct the spring precipitation days over the last 370 years in the drainage. The main significant decreasing trend of the number of the spring precipitation days occurred during 1665—1717, while the significant increasing trends happened during 1805—1841 and 1914—1943. The reconstructed series of the number of spring precipitation days has quasi-periodic variations of 3.3, 2.1, 2.5, 12.3 and 32.0 years with the dominated short periodical changes. The long cycle of 32 years is shown quite clearly in the 10-year smoothed sequence. The maximum spring precipitation days occurred mainly in the 1630s, 1840s and 1940s, while the lowest number of spring precipitation days for the 10-year average occurred in the 1710s.展开更多
The climate of the past 1000 years is an important context for evaluating the recent climate warming.However,there are few 1000-year-long climate reconstructions with annual resolution in the Qing-hai-Tibet Plateau.In...The climate of the past 1000 years is an important context for evaluating the recent climate warming.However,there are few 1000-year-long climate reconstructions with annual resolution in the Qing-hai-Tibet Plateau.In this paper,a dendroclimatic analysis was conducted for the radial growth of Qilian juniper from the upper forest limit in Wulan,Qinghai Province.The results of correlation analysis between the tree-ring widths and the climate variables indicate that the growth of junipers at the upper forest limit is mainly limited by low temperatures of September,November and February of the pregrowth season,and July of the current growth season.There is no significant correlation between the tree-ring widths and precipitation.A mean temperature from the previous year's September to the current year's April was reconstructed for the Wulan area since A.D.1000.The reconstruction can explain 40.8% of the instrumental variance in the calibration period(1856―2002).The reconstruction shows that the 20th century is the warmest 100 years,and the 1990s is the warmest decade during the past 1000 years,while the coldest 100 years and decade occur at 1600―1699 and 1642―1651,respectively.The variations are verified well by the temperature reconstruction of the middle Qilian Mountain(QL) and the total organic carbon(TOC) in the Qinghai Lake sediments.The comparison of our reconstruction with the annual temperature reconstruction of extra-tropical Northern Hemisphere suggests that the climate of Wulan during the Medieval Warm Period is of obvious regional specialty,but there was a good response to the climate of hemispheric scales during the recent 400 years.展开更多
基金supported by the National Key Basic Research Project(Grant No.G200O48701)the National Natural Science Foundation(Grant No.40265002)+1 种基金the Project(Grant No.2002CCA04600)the Xinjiang Commission of Science and Technology(Grant No.980103002).
文摘The tree-ring cores of Tianshan spruces collected from nine sites in the Urumqi River drainage of the middle Tianshan Mountains were used to establish three types of the tree-ring width chronologies over the last 370 years, using the international standard method of dendrochronology. Our study demonstrates that dendrochronology can be better used to reconstruct the number of the precipitation day than to reconstruct the precipitation amount in middle Tianshan Mountains. It is found that the residual chronology among the three tree-ring width chronologies has the best relationship with number of spring precipitation days from May 20 to June 8. The chronologies at Haxionggou B site and Zaierdegou site in the Urumiqi drainage have the highest correlation with the observed number of spring precipitation days at Daxigou meteorological station, and are used to reconstruct the spring precipitation days over the last 370 years in the drainage. The main significant decreasing trend of the number of the spring precipitation days occurred during 1665—1717, while the significant increasing trends happened during 1805—1841 and 1914—1943. The reconstructed series of the number of spring precipitation days has quasi-periodic variations of 3.3, 2.1, 2.5, 12.3 and 32.0 years with the dominated short periodical changes. The long cycle of 32 years is shown quite clearly in the 10-year smoothed sequence. The maximum spring precipitation days occurred mainly in the 1630s, 1840s and 1940s, while the lowest number of spring precipitation days for the 10-year average occurred in the 1710s.
基金Supported by National Basic Research Program of China (Grant No. 2005 CB422002)National Natural Science Foundation of China (Grant Nos. 40671194 and 40371118)the Knowledge Innovation Program of Institute of Geographic Sciences and Natural Resources Research (Grant No.CXIOG-A05-12)
文摘The climate of the past 1000 years is an important context for evaluating the recent climate warming.However,there are few 1000-year-long climate reconstructions with annual resolution in the Qing-hai-Tibet Plateau.In this paper,a dendroclimatic analysis was conducted for the radial growth of Qilian juniper from the upper forest limit in Wulan,Qinghai Province.The results of correlation analysis between the tree-ring widths and the climate variables indicate that the growth of junipers at the upper forest limit is mainly limited by low temperatures of September,November and February of the pregrowth season,and July of the current growth season.There is no significant correlation between the tree-ring widths and precipitation.A mean temperature from the previous year's September to the current year's April was reconstructed for the Wulan area since A.D.1000.The reconstruction can explain 40.8% of the instrumental variance in the calibration period(1856―2002).The reconstruction shows that the 20th century is the warmest 100 years,and the 1990s is the warmest decade during the past 1000 years,while the coldest 100 years and decade occur at 1600―1699 and 1642―1651,respectively.The variations are verified well by the temperature reconstruction of the middle Qilian Mountain(QL) and the total organic carbon(TOC) in the Qinghai Lake sediments.The comparison of our reconstruction with the annual temperature reconstruction of extra-tropical Northern Hemisphere suggests that the climate of Wulan during the Medieval Warm Period is of obvious regional specialty,but there was a good response to the climate of hemispheric scales during the recent 400 years.
