基于树木年轮宽度重建塔里木盆地西北缘水汽压变化

利用新疆阿合奇县以南黑尔塔格山区的天山云杉树木年轮宽度资料,基于树轮宽度指数与阿合奇气象要素的相关分析发现该树木径向生长主要受水分条件限制。选择相关系数较高且生理意义明确的时段和要素,建立了树轮宽度标准年表与阿合奇上年8月至当年6月的平均水汽压的线性转换方程(R²=66.4%,R_adj²=65.1%,p<0.001)。器测资料线性趋势分析表明,近56年来阿合奇的降水和水汽压呈一致的上升趋势。阿合奇1656-2012年的水汽压序列经历了4个偏干阶段(1666-1689年、1722-1749年、1820-1880年、1909-1988年)和4个偏湿阶段(1688-1721年、1750-1819年、1881-1908年、1989-002年)。在95%的置信水平上,重建序列存在显著的56.8 a、13.4 a、10.7 a、6.9 a、5.4 a、4.3 a、3.8 a和2.6 a的周期,其56.8 a的低频周期和6.9 a的周期对应天山山区的树轮重建序列中记录的周期特征。滑动T检验发现了显著性水平达到 0.001的6个突变年份(1720年、1827年、1910年、1751年、1874年、1988年)。重建序列中1988年水汽压增加的突变和1989年以来的偏湿阶段与中国西北(特别是天山山区和南疆西部)20世纪80年代以来增湿过程对应。阿合奇的水汽压重建序列与天山山区和阿克苏的降水记录的干湿阶段一致,但与同位新疆南部天山山区中部巴仑台的干湿阶段并不对应。

Tree-ring Based Water Vapor Pressure Reconstruction in Northwestern Edge of the Tarim Basin

Tree-ring width data from south slope of the Heiertage Mountains, which is located to the south of Aheqi, Xinjiang, China, were collected to develop into chronologies. Correlation analysis between tree-ring width index and climatic factors of Aheqi meteorological station showed that tree radial growth was dominated by moisture status including precipitation, relative humidity and water vapor pressure. The optimum period and factors which is of high coefficient and physical significance, water vapor pressure from last August to current June in Aheqi was selected to establish the linear transfer function with tree-ring width standard index. The explained variance of the function is 66.4%. The observational data analysis in Aheqi indicated that precipitation, water vapor pressure and temperature show a consistent increasing tendency. Four drought periods (1666-1689, 1722-1749, 1820-1880, 1909-1988)and four wet periods (1688-1721, 1750-1819, 1881-1908, 1989-2002) were found in the reconstructed water vapor pressure series during 1656-2012. The drought and wet periods are also coincided with the reconstructed precipitation in Tianshan Mountains and Akesu, however, not with that from Baluntai in the central Tianshan Mountains in south Xinjiang. The multi-taper method (MTM) spectral analysis revealed the cycles of 56.8 a, 13.4 a, 10.7 a, 6.9 a, 5.4 a, 4.3 a, 3.8 a and 2.6 a above the 95% confidence level. In which, the cycles of 56.8 a at low frequency and 6.9 a at high frequency are correspondent with the reconstructed series in Tianshan Mountains. The abrupt increasing change in 1988 and the wet period since 1989 are consistent with the wetting trend in northwest China and especially in south Xinjiang.