利用树木年轮宽度资料重建长白山地区240年来降水量的变化

根据长白山地区水曲柳年轮宽度资料,分析了树木年轮宽度与气候要素的关系,重建了1765年来该地区的降水变化。结果表明:长白山地区近240年降水波动明显,1850年以前降水波动幅度较大,1850—1900年波动比较平稳,并且降水量偏低,1900年以后降水的波动幅度明显增大,且湿润和干旱的持续时间增长,特别是1920年以后,降水波动剧烈;降水减少幅度最大的干旱期是1816—1820年,湿润期是1975—1979年;而1925—1936年和1947—1957年的2个干旱期在持续时间上最为显著。周期分析结果表明,长白山地区降水具有显著的2.64～3.03年、5.28～6.96年以及12.13～22.63年的周期。

Reconstruction of temporal variations of precipitation in Changbai Mountains area over past 240 years by using tree-ring width data

Based on the tree-ring width chronologies of Fraxinus mandshurica in Changbai Mountains area,the relationships between tree-ring width and climatic factors were analyzed,and the temporal variations of precipitation in this area since 1765 were reconstructed.The results showed that over past 240 years,the precipitation in Changbai Mountains area fluctuated evidently.The amplitude of the fluctuation was comparatively great before 1850,and relatively stable from 1850 to 1900,with a low level of precipitation.After 1900,the amplitude of the fluctuation increased significantly,and the durations of wetness and drought were extended.Especially after 1920,the precipitation fluctuated acutely,and several wet and drought periods could be clearly identified.The driest period with an evident decrease of precipitation appeared in 1816-1820,and the wettest period was in 1975-1979.The drought periods which appeared from 1925 to 1936 and from 1947 to 1957 were particularly notable for their durations.There were significant periodical variations of precipitation in the Changbai Mountains area,and the periodicities were 2.64-3.03 years,5.28-6.96 years,and 12.13-22.63 years,respectively.