摘要
A tree-ring width chronology of 442 years(1567-2008) was developed from Tibetan junipers(S.tibetica) derived from south Tibet in western China.Three versions of chronology were produced according to standard dendrochronological techniques.The correlation and response analysis displays a high correlation between the standard tree ring-width chronology and observed annual mean precipitation series during the period 1961-2008.Based on a linear regression model,an annual(prior August to current July) precipitation for the past 229 years was reconstructed.This is the first well-calibrated precipitation reconstruction for the Nanggarze region,south Tibet.The results show that relatively wet years with above-average precipitation occurred in 1780-1807,1854-1866,1886-1898,1904-1949,1967-1981 and 2000-2008,whereas relatively dry years with below-average precipitation prevailed during 1808-1853,1867-1885,1899-1903,1950-1966 and 1982-1999.Common dry/wet periods during 1890s,1910s,1940s-1960s and 1980s were also identified from other moisture reconstructions of nearby regions,indicating a synchronous climatic variation in south Tibet.Abrupt change beginning in 1888 was detected,revealing a transition from wet to dry conditions in south Tibet.Power spectrum analysis reveals significant cycles of 28-year,5.5-5.6-year and 3.3-year during the past 200 years.
A tree-ring width chronology of 442 years(1567-2008) was developed from Tibetan junipers(S.tibetica) derived from south Tibet in western China.Three versions of chronology were produced according to standard dendrochronological techniques.The correlation and response analysis displays a high correlation between the standard tree ring-width chronology and observed annual mean precipitation series during the period 1961-2008.Based on a linear regression model,an annual(prior August to current July) precipitation for the past 229 years was reconstructed.This is the first well-calibrated precipitation reconstruction for the Nanggarze region,south Tibet.The results show that relatively wet years with above-average precipitation occurred in 1780-1807,1854-1866,1886-1898,1904-1949,1967-1981 and 2000-2008,whereas relatively dry years with below-average precipitation prevailed during 1808-1853,1867-1885,1899-1903,1950-1966 and 1982-1999.Common dry/wet periods during 1890s,1910s,1940s-1960s and 1980s were also identified from other moisture reconstructions of nearby regions,indicating a synchronous climatic variation in south Tibet.Abrupt change beginning in 1888 was detected,revealing a transition from wet to dry conditions in south Tibet.Power spectrum analysis reveals significant cycles of 28-year,5.5-5.6-year and 3.3-year during the past 200 years.
基金
funded by the National Basic Research Program of China (973 Program) (No.2010CB950104)
the Chinese Academy of Sciences Visiting Professorship for Senior International Scientists (Grant No.2009S1-38)
the Chinese Academy of Sciences (CAS) 100 Talents Project (29082762)
the NSFC (Grant no.40871091)
