利用树轮资料重建天山中段南坡巩乃斯地区公元1777年来平均最高气温变化

摘要

利用年轮平均灰度年表重建了天山巩乃斯地区自公元1777年来当年5月至8月平均最高气温,方差解释量达41％(调整自由度后为39％).过去232年来,巩乃斯地区平均最高气温变化存在2个偏冷阶段和1个偏暖阶段.重建序列具有154年、77年、2.7年和2.3年的准周期,并且在1842年前后、1880年前后、1923年前后发生了突变.与北半球平均最高气温网格点资料和多种涛动指数的相关性分析表明,巩乃斯地区平均最高气温变化不仅反映了区域气候变化,对于大范围气候变化也存在一定程度上的响应.%The Gongnaisi region is located on the southern slope of the Central Tien Shan Mountains in Xinjiang Province. In recent years, there are some dendroclimatological studies in this region, which were focused on the analyses of correlations of chronologies with meteorological data and the precipitation reconstruction. However, the temperature variation history of the region remains unclear.Healthy spruce ( Picea schrenkiana) trees grow in sparse ground vegetation. Spruce trees with little or no apparent evidence of human or other disturbances were selected for sampling. Two cores(5. 15mm diameter) were extracted from each tree in different directions for cross-dating. A total of 62 cores from 31 spruce trees were collected from AKS sampling site(2420 ~2482m a. S. L.,43°12'12. 8" N and 84°47'47. 7" E) in May 2009,which is located in a mountainous area of the Aikendaban region. All of tree-ring samples were dried, mounted, surfaced and cross-dated following standard dendrochronological procedure. Three kinds of tree-ring width data(TRW,EWW and LWW)and five kinds of tree-ring gray values( TRG,EWG,LWG,MXG and MIG)were obtained through a tree-ring image analysis system(WINDENDRO? 2005a) ,which includes a high resolution scanner,a PC computer and a software program. The quality control of cross-dating was carried out using COFECHA and ARSTAN program was used for de-trending. After all the processes,we obtained three kinds of chronologies( STD, RES and ARS)of tree-ring width data and gray values.Based on the tree-ring data analysis, mean maximum temperature from May to August of the Gongnaisi region from 1777 to 2008 A. D. Has been reconstructed by the tree-ring average gray values. For the calibrated period (1958 ~ 2008 A. D. ) ,the predictor variable accounts for 39% of the variance of mean maximum temperature data. The mean maximum temperature reconstruction shows that there are 34 warm years and 38 cold years. The warm events (lasting for more than three years)were 1861 ~ 1864 A. D., 1873 ~ 1876A. D. And 1917 ~ 1919A. D. ; and the cold events were 1816 ~ 1818A. D., 1948 ~ 1950A. D. And 1957 - 1959A. D. Furthermore, these years and events correspond well with historical documents. By applying a 11-year moving average to our reconstruction, only one period with above average reconstructed mean maximum temperature (1777 ~ 2008A. D. ) comprise 1845 ~ 1925A. D. ; the two periods below average consist of 1788 ~ 1844A. D. And 1926~2001 A. D. The reconstructed mean maximum temperature has increased since the 1990s and agreed well with instrumental measurements in the North Western China in the recent 50 years. The power spectrum analysis shows that there are 154-,77-,2. 7- and 2. 3-years cycles in our reconstruction, which may be associated with solar activity and quasi-biennial oscillation ( QBO). The moving t-test indicates that the significant abrupt changes were presented in about 1842A. D., 1880A. D. And 1923A. D. The significant correlations between our reconstruction and the gridded dataset of the Northern Hemisphere and three kinds of index (SOI, APOI, and AOI) may imply that mean maximum temperature of the Gongnaisi region is possibly influenced not only by local,but also by multiple large-scale climate changes to some extent.