天目山树轮碳同位素与周边地区旱涝变化关系的研究

A Study on Relation between Tree Ring Carbon Isotopes of Tianmu Mountains and Flood/Drought in the Peripheral Areas

根据帕尔默干旱模式的基本思路,建立动态的能反应旱涝持续特征的适合于天目山地区的旱涝指数。对采自天目山的柳杉树轮进行交叉定年后,测得树轮的1δ3C年序列,将1δ3C去除大气CO2趋势影响后的高频变化与不同时段的旱涝指数进行相关分析,结果显示:春夏季的旱涝指数与当年和滞后一年的1δ3C序列有着比较显著的相关性,表明树轮1δ3C对春夏季旱涝的发生有着比较好的响应。根据此显著相关性,利用多元回归方程重建了历史时期的春夏季旱涝指数,分析表明天目山地区春夏季旱涝的发生具有比较明显的年代际变化特征,为研究该地区气候变化特征提供了较可靠的参考依据。

Baesd on Palmer drought index,a flood/drought index series from 1951 to 1996 in the Tianmu Mountain area was established, and this dynamic index can reflect the persistent character of floods/ droughts. The tree a-cellulose δ^13C time series from 1835 to 1997 was obtained based on cross-dating tree rings age from the Tianmu Mountain, Zhejiang Province. After removing the long-term decrease trend, which is related to atmospheric CO2 concentration of the δ^13C series, we analyzed the correlation between the δ^13C and the flood/drought index of different periods, The results suggest that both the same year and the next year tree ring δ^13C are distinctly related with the spring and summer drought indices, showing that the δ^13C better responsed to the spring and summer flood/drought. Based this better correlation and using the multiple regression method, we reconstructed the historical spring and summer flood/drought index from 1835 to 1996. The reconstructed series shows obvious decadal variability, and thus provides a reliable reference for the local climatic change study.