树轮记录的西藏东北部过去552 a上年10月至当年5月降水量变化  

Tree-ring Recorded 522-year Precipitation from Previous October to May in Northeastern Tibet,China

作　　者：尚华明[1] 洪建昌[2] 张瑞波[1] 范子昂[1] 陈峰[1] SHANG Huaming;HONG Jianchang;ZHANG Ruibo;FAN Ziang;CHEN Feng(Institute of Desert Meteorology,China Meteorological Administration,Xinjiang Laboratory of Tree Ring Ecology,Key Laboratory of Tree-ring Physical and Chemical Research of China Meteorological Administration,Urumqi 830002,China;Tibet Climatic Center,Lhasa 850000,China)

机构地区：[1]中国气象局乌鲁木齐沙漠气象研究所新疆树木年轮生态实验室中国气象局树木年轮理化研究重点实验室,乌鲁木齐830002 [2]西藏自治区气候中心,拉萨850000

出　　处：《山地学报》2018年第6期821-832,共12页Mountain Research

基　　金：中央级公益性科研院所基本科研业务费(IDM201102);国家自然科学基金(91547115;41205124;41271098);气象行业专项(GYHY201206014)~~

摘　　要：青藏高原是气候变化研究的热点区域,由于其极端寒冷、干旱的气候条件,环境因子对树木生长的限制作用明显,高原东部地区广泛分布的长龄针叶树成为过去变化研究的重要代用资料。本文利用位于西藏东北部3个采样点的川西云杉树木年轮资料,建立了宽度年表。树轮宽度指数与类乌齐和昌都气象站气温、降水资料以及格点PDSI的相关与响应分析发现,上年10月至当年5月的降水量是制约该区域树木的径向生长的主要气候因子,且具有明确的生理意义。在此基础上,建立了树轮宽度指数与降水量的线性转换方程(n=32,R^2=52. 9%,F=33. 7),重建了西藏东北部公元1460—2011年期间上年10月至当年5月的降水量序列,确定其存在6个明显的偏湿阶段(1512—1533、1551—1630、1659—1729、1771—1790、1838—1862、1976—2011年)和5个明显的偏干阶段(1460—1511、1591—1614、1730—1770、1791—1837、1892—1930年)。空间代表性分析表明重建序列能较好地代表西藏东部地区(94°E～100°E,29°N～33°N)的降水变化。本文降水序列与研究区周边的树轮降水记录的对比发现,其共同的特征是19世纪早期的持续干旱和1980年中期以来的增湿过程,但本序列中最长的湿润期(1659—1729年)以及20世纪早期的干旱期(1892—1930年)与其他两条降水记录并不一致。近20年来明显的增湿过程可能是由于高原增温导致对流活动增强,进而增加有效降水。树轮降水记录不一致的原因除了降水存在较强的局地性特征以外,还可能是由于研究区处在南亚季风和西风系统的交互作用区。As the third pole of the world,the Tibetan Plateau has been the hotspot of the large-scale climate change research.The long-lived needle-leave trees widely distributed in the plateau provide important proxies for past climate change.Three tree-ring width chronologies and their composite chronology of Picea likiangensis var.balfouriana were established in Changdu district of northeastern Tibet.Correlation and response analysis between tree-ring width index and climatic factors revealed that the total precipitation from previous October to May in the current year was the dominant climatic factor on their radial growth.The linear transfer function(n=32,R2=52.9%,F=33.7)was introduced to reconstruct the precipitation history during 1460-2011.The reconstructed series indicated that there were six distinct wet periods(1512-1533,1551-1630,1659-1729,1771-1790,1838-1862,1976-2011)and five drought periods(1460-1511,1591-1614,1730-1770,1791-1837,1892-1930).Spatial representativeness analysis demonstrated the reconstructed series could reflect regional precipitation change in the eastern Tibet(94°E^100°E,29°N^33°N).Comparison between this study and other tree-ring based precipitation records in the surrounding area confirmed the consistency of lasting drought in the early 19th century with the wetting trend since the mid-1980s.However,the longest wet period(1659-1729)and the drought period in the early 20th century in this study were inconsistent with other two precipitation records.The significant wetting trend in the recent 20 years was probably resulted from the enhancement of vertical convention due to land surface warming.The inconsistency among tree-ring precipitation records was caused by both the distinct localized precipitation and the limited size of studied area,which lies in the interaction area of the South Asian monsoon and the westerlies.

关 键 词：树木年轮 川西云杉 降水量 气候变化 西藏 

分 类 号：P467[天文地球—大气科学及气象学]