Reconstruction of Annual Precipitation in Shandan Based Tree-Ring since 1783 A.D.

The tree-ring chronologies were established according to samples from Shandan.Single correlation calculation indicated that the correlations were significant between the tree-ring chronologies and previous year′s August to present year′s June(A to J) total precipitation,and the correlation coefficient was 0.654.Using DHG(RES)tree-ring chronology,the previous year′s August to present year′s June precipitation during the last 224 years was reconstructed,with an explained variance of 42.8%.The reconstructed equation was stable by crossing-test.The reconstruction precipitation is compared to historical archives and other tree-ring reconstructions in Northwest China.The results reveal common climatic extremes and change over much of Northwest China.Many of these events have had profound impacts on the peoples over the past several centuries.The reconstructed precipitation series for Middle Hexi Corridor during the last 224 a had significant period cycles of 4.2 a,3.4 a,3.2 a,2.6 a.The abrupt change of precipitation occurred in 1887,1908.