Circulation characteristics of interannual and interdecadal anomalies of summer rainfall in north Xinjiang
新疆北部汛期降水年际和年代际异常的环流特征

The precipitations in north Xinjiang in rainy seasons (July and August, or JA) show distinct interannual and interdecadal variations. In this study, analyses are performed by using NECP/NCAR reanalysis data on respectively atmospheric circulation anomalies associated with three time scales, which are interdecadal, interannual after removing interdecadal variation, and interannual variations on different interdecadal backgrounds. The results show that there are different physical mechanisms for three time scales, and interdecadal backgrounds are important. Remarkable equivalent-barotropic structure circulation anomalies over Eurasia mid-high latitude are responsible for rainfall anomalies in Xinjiang. It is pointed out from climate and interdecadal circulation change that there are vapor anomalies associated with 3-segment relayed transportation from Somali jet stream to Xinjiang. Both Somali jet stream and tropical India Ocean are also the important vapor resources for mid-Asia and Xinjiang.