Monthly Mean Temperature from February to March in Aksu River Basin on Southern Slope of Tianshan Mountain Recorded by Tree Ring

The tree ring samples of Schrenk Spruce(Picea Schrenkiana Fisch.et Mey) collected from six sites in Aksu River Basin and standard dendrochronological method on southern slope of Tianshan Mountain in 2005 are used to study six tree ring width chronologies.The mean temperatureseries from February to March in recent 378 years can be reconstructed by using the tree-ring standardized chronologies.The reconstructed period is of obvious tree physiology,and the obtained result is reliable through the verification in many ways. The reconstructed temperature series showed the quasi-periods of 3.6,42 and 50.4 years and theabrupt change in 1719 and 1827.The reconstructed temperature series have nine warm and nine cold stages, the coldest stage is in 1911-1922,which is lower than average 1 ℃ or more,and the warmest stage is in 1640-1651,which is higher than the average 1 ℃.The temperature continuously decrease from the early 20thcentury to 1915,the mean temperaturemaintain at the lowest level in 1915-1921,the temperature value is-3 ℃ in 1916,it is the lowest year over the past 378 years.After 1921 years,the temperature slowly rise until the late 1930s,it drop slowly again from 1940s to 1970s. The mean temperature from February to March rapidly increase in Aksu River Basin,southern slope of Tianshan Mountain from middle-late 1970s to now.