| Using the summer rainfall data from twenty-six observatories in ShanDong Province from 1961 to 2001, the subtropical high index data from 1961 to 2002 and the monthly mean reanalysis data of Wind, moisture, height and OLR of NCEP/NCAR from 1958 to 1998, the characteristics of abnormal circulation in the northern Hemisphere, the abnormal strength and location of Subtropical High, the abnormal strength of monsoon and water vapor transport over the areas of East Asian were studied. The studies in this paper are significant for understanding and predicting the summer rainfall over Shandong area.Classified by Z-index, It was found that there were more floods from 1961 to 1978 and more droughts from 1979 to 1992. Analysis using method of Morlet and Mexican hat wavelet transform shows that there were 2 to 5 years and quasi-7 years oscillations in the summer rainfall over Shandong.There is almost opposite deployment of movement, the movement of convergence and divergence on level of 200hPa and 925hPa, during flood year and drought year. During flood years, the center of negative anomaly is around Ural Mountains, the center of positive anomaly is around high-latitude of East Asia and another negative and positive center are over Okhotsk Sea and the North-West Pacific, respectively. The positive and negative anomaly centers at 500hPa level formed the anomaly "wave train" from lower latitude to higher latitude over east Asia. The teleconnection pattern called East Asia-Pacific pattern (EAP) plays important roles in the summer rainfall in Shandong area. Study shows that weaker Okhotsk sea high, northward location of subtropical high and stronger Indian low, are likely to lead to more rain in Shandong province in summer.It was found that the "key regions" from which moisture transports influenced Shandong summer rainfall lies in tropical India Ocean, South China Sea to tropical west Pacific, China mainland to Japan Sea and the upstream area in westerly belt by analysis of SVD method on water vapor transport. The moisture transports in flood years are much more than that in drought years. In May and June, the moisture transports from "key regions" are all important to Shandong summer rainfall. In July, although the moisture transport from tropical Indian Ocean reaches its annual maximum to Shandong, its contribution to summer rainfall over Shandong during July and August is undistinguished. On the other hand, the contribution from sub-tropical West Pacific is evident.Analysis on index of sea-land thermal difference resulted that there are periodical oscillations of 2-6 years in the Subtropical High, trough systems in the middle latitude. The year with strong (weak) index are associated with EAP (negative EAP) pattern in which the Subtropical High is abnormally northward (southward) and more (less) summer rainfall in Shandong.There is teleconnection relations between Shandong summer rainfall and the convective activities happening in tropical areas in spring and summer accomplished by Rossby waves. During the years of strong monsoon, the convective activities happening in tropical India Ocean and tropical west Pacificand Walker circulation are much stronger than that during the years of weak index, but the convective activities happening in tropical east Pacific are weaker than those during the years of weak monsoon.Based on the analysis mentioned above, a conceptual diagram explaining the physical process is put forward:Stronger (weaker) convective activities in tropical areas stronger upward (downward) vertical anomaly stream in tropical areas more (less) moisture transports from "key regions" to Shandong stronger (weaker) Hadley and Walker circulation stronger (weaker) East Asian summer monsoon EAP (negative EAP) in 500hPa upward (downward) vertical anomaly stream rise in Shandong Subtropical High abnormally located northward (southward) more(less) rain in Shandong Province.
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