The Weakening Relationship between the Precipitation in North China during Rainy Season and the Two High in the Southern Hemisphere

Based on the reanalysis data from NCEP/NCAR and other observational data, interannual correlation of the Mascarene high (MH), Australian high (AH) and rainfall of North China during rainy season from 1948 to 2003 are examined. It is shown that there exits significant negative correlation between the two high and rainfall of North China during rainy season. The variability of precipitation in North China over the past 50 years is characterized by the three interdecadal periods. Associated with the three stages, anomaly patterns of southern hemisphere atmospheric circulation are respectively: Antarctic oscillation is negative phase, the two high are lower than the normal when precipitation in North China is in the flood period. The filed distribution of sea level pressure in 20degS~50degS is ldquo-+-+rdquo pattern, MH is higher than normal and AH is lower than the normal when precipitation in North China is in the adjusting period. Antarctic oscillation is positive phase, both high are higher than the normal when precipitation in North China is in the drought period.