Interdecadal Characteristics of the Influence of Northward Shift and Intensity of Summer Monsoon on Precipitation over Northern China in Summer

The location of northward shift of East Asian Summer Monsoon is calculated by using NCEP/NCAR air temperature and specifichumidity reanalysis data in recent 50 years.It is found that there is obvious interdecadal change in the north boundary of monsoon region,and the years with the far north boundary centralize in 1950′s and 1960′s,with the far south,in 1980′s and 1990′s,the interdecadal change of north boundary of summer monsoon in each monsoon region is consistent.The regional monsoon index is defined by using these data,in order to reflect the relationship between the intensity of East Asian summer monsoon and drought/flood in Northern China and improve the low correlation between the situation of northward shift of summer monsoon and drought/flood in Northern China,and the arid and semiarid regions where is sensitive to the intensity of summer monsoon is compared by composite analysis.In the last,the relationships between the regional summer monsoon index and the precipitation on different time scales in July and August is discussed by wavelet analysis.The correlation between regional summer monsoon index and precipitation in summer is high on interdecadal scale about 15 years and on interannual scale of 3~5 years.