乌鲁木齐河源467年春季降水的重建与分析

Reconstruction and analysis of 467-year spring precipitation series in the Urumqi River Head

通过相关分析发现,乌鲁木齐河树轮宽度年表与大西沟气象站4-5月降水相关性较好,最高单相关系数为0.490(α=0.001),且具有明显的树木生理学意义。本文使用逐步回归分析方法筛选出哈熊沟C点和波尔钦沟标准化年表建立重建方程,交叉检验结果显示该方程具有较好的稳定性,利用该方程重建了乌鲁木齐河源大西沟气象站467年春季(4-5月)降水的变化序列,解释方差达41.6%。对该序列的特征分析表明:(1)467年来乌鲁木齐河源4-5月降水经历了13个偏湿及12个偏干阶段;(2)467年来乌鲁木齐河源4-5月降水变化中,出现276个正常年、86个偏干年、98个偏湿年、5个干旱年、2个湿润年,最长的偏湿阶段为1646-1687年(42年),最长的偏干阶段为1704-1733年(30年),最湿的偏湿阶段为1694-1703年(平均降水量为86.9mm,比最近41a平均偏多18.7%),最干的偏干阶段为1635-1645年(平均降水量为60.0 mm,比最近41年平均偏少18.0%),最湿润年为1697年(98.2 mm,+34.2%),最干旱年为1951年(42.6 mm,-41.8%);(3)467年的重建春季降水长序列具有2.04-2.15年、2.25-2.31年、2.38年、31年、34.44年、51.67年和62年的变化准周期,并且在1635年、1704年、1758年、1781年、1832年和1915年发生过降水突变。

Correlation calculation indicates that the tree-ring chronologies positively correlate with spring （April to May） precipitation of the Daxigou Meteorological Station significantly, with the greatest single correlation coefficient of 0. 490 （the significance is much greater than 99.9 percent level）. The result has distinct physiological significance. Using HXC. STDt and BEQ. STDt＋2 tree-ring chronology series, the long-term sequence of spring precipitation was reconstructed with an explained variance of 41.6%. It is verified that the reconstructed pracipitation was reliable. The reconstructed series show that （ 1 ） in the 467 years, the spring precipitation in the Urumqi River Head experienced 13 wet periods and 12 dry periods; （2）in the past 467 years, there were 276 normal precipitation years, 86 dryish years, 98 dampish years, 5 dry years and 2 wet years, and the longest dampish period was 1646 - 1687 （42 years）, the longest dryish period was 1704 - 1733 （30 years）. The great wettest period was 1694 - 1703 （ the mean precipitation was 86.9 mm, 18.7% higher than that of the recent 41 years）, and the great driest period by far was 1635 - 1645 （ the mean precipitation was 60.0 mm, 18.0% lower than that of the recent 41 years）, the wettest year was 1697 （ the mean precipitation was 98.2 mm ,34.2% higher than that of the recent 41 years ）, the driest year was 1951 （the mean precipitation was 42.6 mm, 41.8% lower than that of the recent 41 years） ; （3） the reconstructed long-term spring precipitation sequence had 2.04 -2.15 a, 2.25 -2.31 a, 2.38 a, 31 a, 34.44 a, 51.67 a and 62 a changing periods, and the reconstructed precipitation sequence had the abrupt changes in 1635, 1704, 1758, 1781, 1832 and 1915.