Different Configurations Of Tropical Summer Monsoon Strengths In South Asia And East Asia And Their Effects On Summer Precipitation In China

Several sets of data are used in this study:(1)monthly averages of outgoing longwave radiation(OLR)data from National Oceanic and Atmospheric Administration,(2)monthly means of elements from the National Centers for Environmental Prediction-National Center for Atmospheric Research(NCEP-NCAR)reanalysis dataset,(3)CN05.1 daily precipitation dataset obtained by more than 2,400 sites data from China Meteorological Bureau.These datasets span the years from 1979 to 2017s.Many statistical methods are used,including related analysis,synthetic analysis,regression analysis,empirical orthogonal function analysis and wavelet analysis.This study is mainly made to investigate the relationship of interannual change between East Asian tropical summer monsoon and South Asian summer monsoon,and the impact of different strength change configurations on China summer rainfall.The results show that:There is a certain independence between interannual variabilities of East Asian tropical summer and South Asia Summer monsoon.However,there are two configurations with inphase and out-of-phase variations between the intensity of two monsoons.The identical and inverse intensity change indices are defined.The results of EOF also indicate that there are two different modalities,and the time series are highly correlated with the defined different configuration indices.The in-phase mode may be related to the influence of the strong El Ni(?)o(La Nina),and the antiphase mode may be influenced by El Ni(?)o(La Ni(?)a)and Indian Ocean Basin-wide.When South Asia summer monsoon and East Asian tropical summer monsoon are both stronger,the western Pacific subtropical high is weaker with the location to the west,and the Iran high is weaker with the location to the east.There're cyclonic circulations over the northern Indian peninsula and the South China Sea-Western Pacific.There are obvious water vapor convergence centers in the north of the Indian Peninsula and the South China Sea,which are favorable to the activities of two tropical monsoons,and vice versa.When the East Asian tropical summer monsoon is stronger and the South Asian summer monsoon is weaker,the western Pacific subtropical high is weaker with the location to the east.which is conducive to the activity of east Asian tropical summer monsoon.However,the Iranian high is eastward and stronger,which isn't conducive to the activity of south Asian summer monsoon,and vice versa.When the intensity of East Asian tropical summer monsoon and South Asian summer monsoon changes in different configurations,the effects on China summer rainfall are different.When East Asia tropical summer monsoon and South Asia summer monsoon are stronger,the northeast wind on the northwestern side of the cyclone inhibits water vapor to the south of China,and the southeast wind on the southwest side of the anticyclone near the Japanese sea provides water vapor conditions for North China.There are Less precipitations in the middle and lower reaches of the Yangtze River,and more precipitations in North China and the South China.The rainy model of summer rainfall in the eastern part shows "less in the middle,more in the south and north".When the intensity of East Asia tropical summer monsoon and South Asia summer monsoon changes in out-of-phase,with stronger East Asia tropical summer monsoon and weaker South Asia summer monsoon,the central position of anticyclone near the Japanese sea moves west related to in-phase,low pressure slot in the north moves to south and becomes stronger.North China is controlled by northwest airflow,and South China is controlled by northeast airflow.The precipitation in eastern China shows in consistently less rainy pattern.