The 168 Years Reconstruction of May-August Precipitation from Tree-Ring Data in Shihezi Region

According to correlation census,the standarded chronology of tree-tree width from Tianshan spruce of Banfanggou in the Manas River mountainous area on the northern slope of the Tianshan Mountains was significantly correlated with the May-August precipitation in the Shihezi region.The single correlation coefficient was 0.656(P < 0.0001).Based on the chronology,A 168a reconstrution of May-August precipitation was performd for the Manas River basin and the explained variance was 45.3%.The statistical parameter test and independent historical climate record verification showed that the 168-year precipitation reconstruction had good credibility.The May-August precipitation generally experienced 6 partial wet and 6 partial dry periods in the Shihezi region over past 168 years.The wettest-year occured in 1988,the precipitation was 71.7% more than the long-term average,the dryest year appeared in 1945,42.7% less than the long-term average,the longest wet period appeared during 1843~1857,and the longest dry period occured from 1908 to 1924.Power spectrum analysis of the reconstructed precipitation showed remarkable four and eight year cycles for the past 168 years.The May-August precipitation variation possibly related to El Niño-Southern Oscillation (ENSO) in Shihezi region.