树轮记录的过去384a乌鲁木齐河源7月温度变化

July Temperature at the Upper Treeline Recorded in the Tree-Ring in the Headwaters of the rümqi River

利用采自乌鲁木齐河源上树线跃进桥东采样点的雪岭云杉树轮样本,分析了其年表特征和气候响应特点.结果表明:采样点树轮早材密度标准化年表与和大西沟气象站7月份平均最高温度具有很好的正相关关系.用跃进桥东采样点的早材密度标准化年表序列,可较好地重建乌鲁木齐河源1623—2006年的7月平均最高温度,1959—2006年48a重建值对实测值的解释方差达42.4%,交叉检验表明重建结果是稳定可靠的.近384a来乌鲁木齐河源7月平均最高温度距平平均值为0.37℃.乌鲁木齐河源近384a的7月平均最高温度经历了5个偏暖阶段和4个偏冷阶段,与乌鲁木齐河源1号冰川的进退有一定的响应关系.近384a乌鲁木齐河源7月平均最高温度具有192a(99%)、29.3a(99%)6.8a(90%)、4.3a(90%)、4a(90%)、3.7a(90%)、2.3a(90%)、2.1a(95%)的周期变化.滑动T检验表明,乌鲁木齐河源近384a的7月平均最高温度在1645年,1665年,1726年,1807年,1833年,1855年,1878年,1929年和1954年发生了突变.

Using tree rings of Picea schrenkiana sampled from the upper treeline in the headwaters of the rümqi River,21 tree-ring density series were developed,and then the earlywood density（EWD） chronology was established.Analyzing the characteristics of the chronologies and their respond to climate factors,the EWD chronology was found that correlates at 0.651 with the anomaly of maximum mean temperature in July over the period 1959—2006,which explained 42.4% of the variance in the reconstruction（F=33.805,P0.0001）.According to the temperature reconstruction in the headwaters of the rümqi river,the anomaly of mean maximum temperature over the period 1623—2006 was 0.37 ℃.The temperature reconstruction has a good response to the history records,temperature reconstructions from tree-ring and glacial change.The results reveal the common climatic extremes and climate change over Northwest China.Many of these events have had profound impacts on the peoples over the past several centuries,for example the 1640s great drought.Multitaper spectral analysis indicates that there were some low-and high-frequency cycles with the periods of 192 a,29.3 a,6.8 a,4.3 a,4 a,3.7 a,2.3 a and 2.1 a.Abrupt change of temperature occurred in 1645,1665,1726,1807,1833,1855,1878,1929 and 1954.