Abstract: Using the NCEP/NCAR monthly mean reanalysis and CMAP (CPC Merged Analysis of Precipitation) precipitation data for the period from 1979 to 2013,the authors define an index of the Migration of Atmospheric Mass over Regions between Eurasia and North Pacific (I_MAMEP) to investigate the interannual variability of spring MAMEP and its impacts on climate anomalies over China.Our results demonstrate that spring MAMEP is mainly characterized by a seesaw-like structure in surface air pressure anomalies,which can also be referred to as Eurasia-North Pacific teleconnection pattern.The I_MAMEP varies with a remarkable long-term trend and periodicities of 2-4 years and 5-7 years as well as distinct interdecadal changes.It is found that an anomalous vertical circulation behaves like a bridge linking Eurasia and North Pacific with the migration of atmospheric mass between these two regions.The atmospheric mass fluxes anomalously converge in the lower troposphere and diverge in the upper troposphere in the west of Eurasia.However,the opposite situations are observed in the western and central Pacific.The wave activity fluxes show that the wave energy propagates eastward from western Europe into the North Pacific,facilitating the maintenance of the anomalous geopotential height disturbances there.In the spring,the I_MAMEP is highly correlated with anomalous rainfall and surface air temperature over China.When the I_MAMEP is positive,precipitation decreases significantly over the north of East Asia,the west of Okhotsk Sea,and the coastal western Europe,as opposed to the increase over the west of Eurasia and the north of China.The anticyclonic circulation in Siberia and the cyclonic circulation in North Pacific in the lower troposphere induce the anomalously high surface air temperature in northern Eurasia,along with the anomalously low temperature in the east of Siberia,Northeast China,North China,Yangtze-Huaihe River valley,Korea,and the south of Japan.The surface air temperature anomalously decreases in much of western Europe and northwestern China.These results are helpful for us to better understand the formation mechanisms for anomalous climate conditions in Eurasia and North Pacific regions in boreal spring.