The Cli mate Change in Autumn Recorded in theδ~(13)C ofTree Rings in the Past300Years at Tianmu Mountain

Based on cross-dated tree ring age,the annual ti me series ofδ13C in theCryptomeria FortuneiHooibrenk ex Otto et Dietr(CF)tree rings collecting from west Tianmu Mountain,Zhejiang Province,weremeasured.The response of theδ13Cseries ofCFtree rings to the change of cli matic factors was analyzed afterobviating the influence of theδ13Ca variationin atmospheric CO2ontheδ13Cti me series of the tree rings by us-ing the Falker’s method.It is found that there is a high correlation between the high frequency oscillation ofthe ti me series ofδ13CintheCFtree rings andthe cli maticfactorsincludingthetemperaturein September,Oc-tober,November and December and the precipitation in September.On the bases,this paper mainly recon-structedthe historical changes of the average precipitation and the highest air temperature in September in thepast 300 years at Tianmu Mountain area.The cli mate variabilityis characterized bythe combination of cold-wetand warm-dry.The statistic result showsthat thefrequency of drought-waterlog andthe cold-warmvariationre-flectedfromthe reconstructed series basically agrees with that recorded by weather station.This indicates thatthe reconstructedresult better reflectsthe historical changes of cli mateinautumnat Tianmu Mountainarea.Thecli matic variation reflected fromthe reconstruction also better corresponds to the cli mate change in the past 500years in China andsome history records and as well as thelake sedi ments of Goulucuo,Qinghai-Xizang Plateau,and the tree ringδ13Crecordsin Altay County of Xinjiang Region but the exchange ti me fromcoldto warmhassome moving which reflects the regional difference of the cli mate changes.The spectrumanalysis shows that inthe reconstructedseries thereis quasi periodicity of 58.82 a,whichis coincident withthe“moment effect”vari-ation periodicity of the planets and earth coming together as well as there are quasi periodicity of 21.28years,13.70years,3.23years,2.63years,2.33years and 2.07years,which coincide withthe solar radiation variationand solar activity and”quasi two-year tropic barometric oscillation”(QBO).This reflects not only the influ-ence of the change of the solar radiation and ENSOphenomenon onthe cli matic changes,but also the record a-bility of the ti me series ofδ13Cintree rings onthe solar radiation change andlarge-scale ENSOevents at Tian-mu Mountain area.