巴丹吉林南缘近两百年来年降水重建及初步分析

沙漠及其边缘地区生态环境脆弱,对气候变化敏感。但沙漠地区有限的森林资源限制了区域百年到千年尺度上的历史气候变化研究。利用采自巴丹吉林南缘的青海云杉年轮宽度资料,重建了区域近191 a(1815—2005年)来的年降水(前一年7月至当年8月的总降水量)变化序列。重建的相关系数是0.636,方差解释量为40.4%,调整自由度后的解释方差R2adj为0.392。重建结果稳定可靠。分析区域过去年降水变化结果可见,19世纪该区域干湿变化频繁,20世纪前半段主要以干旱为主,干湿转变较少。20世纪20年代的干旱事件在巴丹吉林南缘的干旱持续时间更长。周期分析的结果表明,区域年降水量变化有2 a、4 a、64 a等周期。

Tree ring based annual precipitation reconstruction over last 191year at the south edge of Badain Jaran

Desert and its surrounding area are vulnerable and sensitive to climate change. Due to the limited resource of forest, few paleo-climate researches has been conducted at Badain Jaran at century and millenary scale. Based on tree ring width data sampled at south edge of Badain Jaran, a 191 annual precipitation has been reconstructed. The annual precipitation is the total precipitation from previous July to current year August. The correlation between tree ring chronology and observed annual precipitation is 0.636. The reconstruction is reliable and stable and could explain variance 40.4%, adjusted 0.392. During last 200 years, there were frequent dry and wet switches during 19th century, but less abrupt change in 20th century. Drought is the domain condition in the first half part of 20th century. 1920s drought event is a long lasting and extreme drought period at the south edge of Badain Jaran.