Abstract: The inter-decadal variation of summer temperature and its impact factors in Northeast China were studied based on monthly mean temperature observed at 26 stations in Northeast China,74 circulation characteristic indexes from the National Climate Center,and the NCEP/NCAR (National Centers for Environmental Prediction/National Center for Atmospheric Research) reanalysis data from 1951 to 2012.The results demonstrate that there is a significant difference in the atmospheric circulation patterns before and after the inter-decadal transition period of summer temperature in Northeast China from 1951 to 2012.The inter-decadal breaking point in summer temperature is consistent with those in polar vortex area,zonal circulation,and the northeast cold vortex.Therefore,the variation results in these circulation factors may be one of the reasons that lead to a suddenly inter-decadal variation in summer temperature in Northeast China.There is a remarkable inter-decadal transition in the correlation between summer temperature and the main circulation factors at different temporal and spatial scales.The correlation of summer temperature with the western Pacific subtropical high,zonal circulation,and the northeast cold vortex show a strengthening trend at inter-decadal scale,while its correlation with the polar vortex area is weaken with inter-decadal time.The influence scope and intensity of these circulation factors on summer temperature change obviously as well on the inter-decadal scale.

Key words: Northeast China, Summer temperature, Polar vortex area, Zonal circulation, Northeast cold vortex