Variation Characteristics Of Mascarene High And Australian High And Their Interactions With West-Pacific Subtropical High And Summer Rainfall In China

The Mascarene High(MH) and the Australian High(AH) are the main subtropical circulation system of southern hemispheres. And their abnormality have great impact on the northern hemispheres circulation system via the internal conversion of mass/momentum between the northern and southern hemispheres. Based on the reanalysis month data of NCEP/NCAR, the74circulation indexes of National Climatic Center and the160stations precipitation in summer of China, the research of MH, AH and West Pacific Subtropical High(WPSH) of northern hemispheres have been performed. First of all, analysis of MH, AH and WPSH in different duration have been done, including the change of area and location. Secondly, the climatic characters of MH and AH have been comparing with WPSH. Then, with the bridge of cross-equatorial flow, the pattern between the abnormality, occurred by the abnormality of MH and AH, and the abnormality of each circulation of northern hemispheres has been proposed, which will lead the abnormality of East Asian summer monsoon and WPSH. Thirdly, the relationship between MH, AH and the precipitation in summer of China have been studied, and the precipitation area being related to the MH and AH has been given. All researches have been followed as:(1)The three highs have equiform changes in interdecadal variation,thus, the degree of variations are different. The analysis exhibits significant interannual and interdecadal variation of MH, AH and WPSH, furthermore. Results suggest that the climatology and interannual to interdecadal variability of the three highs are highly consistent with each other, MH tend to be more strong, and move towards the southwest since the middle of1970s; In addition, AH and WPSH also get stronger, and move to west.(2) Mascarene high and Australian high anomalies can through cross-equatorial flow cause abnormalities in the Northern Hemisphere circulation system, further affecting WPSH. Cross-equatorial flow as a bridge to reveal MH and AH abnormal that can cause abnormalities in the Northern Hemisphere circulation system, and the impact of WPSH. Herein points out the Somali jet enhancements can cause the Indian summer monsoon, the southwest monsoon and the Nanhai monsoon enhancement, meanwhile Philippines equatorial flow and the east coast of New Guinea equatorial flow enhancement makes the Indian summer monsoon and the Nanhai monsoon weakened, and inhibit the southwest monsoon flow eastward expansion. When MH and AH enhancements, the Philippines and the east coast of New Guinea equatorial flow dramatic enhancement plays a dominant role in making the Indian summer monsoon and the Nanhai monsoon is weak. When the MH and AH positive anomalies can intensify the South Asian high, simultaneously make it extend southwestward, and intensify the Plum rain edge, it also make East Asian subtropical jet extend southward. This integrated configuration is conducive to the WPSH extend westerly and southerly. When the MH and AH negative anomalies, the South Asian high is weak and west retired, subtropical jet stream northward, the Plum rain edge is also weak but East Asian summer monsoon is stronger, thereby conducive to WPSH northward and east retired.(3)There are close relations between summer precipitation in some areas over China with MH and AH. However, by means of singular value decomposition (SVD) analysis,it is shown that the corresponding precipitation pattern from south to north over China presented distinct regional distributionon different time scales. The "+-" patternwere dominant on multi-time changes, while the "-+-" and "-+" patternplay a dominant role on interdecadal and interannual changes, respectively.According to SVD analysis between summer precipitation and MH on month scale, it is clear that the squared covariance is concentrated in the first two modes.Moreover, the critical period for the first SVD mode were from January to March in that year and the year before, and the corresponding critical areas located in the North of the Yellow River (include Hetao area), south of the Yangtze River, and South China. Further more,the second SVD mode indicates that the critical period were from January to February and May to June in that year and the year before, the corresponding critical areas located in most areas of Inner Mongolia and Northeast, and North China. In contrast, the SVD squared covariance is concentrated in the first three modes for AH. The critical period for the first SVD mode were from January to February and April to June in that year and the year before, the corresponding critical areas were in Inner Mongolia, Northeast, North China,south of the Yangtze River, and South China.The critical period for the second SVD mode were from July to August and November to December in that year and the year before, the corresponding critical areas were in Inner Mongolia, North China,and parts of Northwest China. Alternatively, the third SVD mode indicates that the critical period were from March to May and Augustin that year and the year before, the corresponding critical areas located in south of the Yangtze River, and parts of Southwest China.