Interdecadal Variation of the Relationship between AO and Winter Precipitation in China

Using the NCEP/NCAR reanalysis data,the series of AOI(Arctic Oscillation Indices),global SST data,and the observed precipitation at 160 stations of China,the correlation and its interdecadal variation of the AOI and winter precipitation of China in 1951/1952-2007/2008 have been studied.The results show that the correlation coefficients between winter precipitation and AOI are high during 1978/1979-1989/1990.By regression,it is found that the correlation between AO and the East Asian trough is extremely high in this period.Associated with the positive AO,the East Asia trough,Siberian high and East Asia winter monsoon are all weaker.In lower level,there is an anticyclonic circulation anomaly in the Northeast China,and on its southwest side the southeast-ward wind components are enhanced.So it is favorable to the moisture transfer from Northwest Pacific ocean and the Bay of Bengal to middle and east parts of China,which influent on the precipitation in winter.In addition,SST of equatorial east Pacific ocean might influent on the interdecadal variations of the relationship between winter precipitation in China and AO.Associated with the higher relationship between precipitation and AO,the relationship between precipitation and SST is lower.During 1951/1952-1977/1978 and 1990/1991-2007/2008,there is a high correlation between SST and subtropic high.Associated with the higher SST,subtropic high is stronger.In lower level,south wind components in the coastal region of east China and South China Sea are enhanced,which is favorable to the warm current tranfer to the southeast regions of China.Which influent on winter precipitation in the southeast regions of China.