Possible mechanism for the interdecadal change of Xinjiang summer precipitation

Some studies have indicated that an abrupt climate change of Xinjiang summer precipitation has occurred in the late 1980s, changing from warm-dry to warm-wet condition. This study further investigates the corresponding atmospheric circulation anomalies of this interdecadal change basing on NCEP/NCAR and ERA40 reanalysis datasets. The results demonstrate that the intensified and westward East Asian-Pacific teleconnection (EAP) along the East Asian coast made a great contribution to the increase of Xinjiang summer precipitation after the late 1980 s. Before this transition, the EAP was much weaker at a position relatively to the east and presented no contribution to the variability of summer precipitation. The main system affecting that is the anomalous zonal wave train over the Eurasian continent. After this transition, the EAP pattern is observed to be much stronger and more westward than before. Accordingly, the water vapor flow anomalies associated with this intensified and westward EAP extend from the northwestern Pacific to inland China, implying significant increase of water vapor over Xinjiang region, which is partly responsible for the increased summer precipitation after the late 1980 s.