In this study, the NCEP1 (National Centers for Environmental Prediction) daily reanalysis data and GPCC (Global Precipitation Climatology Centre) precipitation reanalysis data from 1961 to 2016 are used to define the spatial range of the northern marginal zone of Asian summer monsoon (ASM). Then, the inter-annual and inter-decadal variations characteristics of precipitation, location and area of the northern marginal zone are analyzed, and the interactions among them are detailedly investigated. Moreover, the physical mechanisms of the summer precipitation anomalies in the ASM marginal zone are explored. The results show that the average position of the ASM northern marginal zone is located in the strip domain which initiates from the central part of the Tibetan Plateau, crosses the Loess Plateau and Northeast China and finally extends to the east coast of Asia. According to the types of underlying surface, regional ecological environment and climate characteristics, the ASM northern marginal zone is divided into three areas: Tibetan Plateau (85°E~105°E), Loess Plateau (105°E~115°E) and Northeast China (115°E~135°E). There is a notable positive correlation between the inter-annual variation of the precipitation in the ASM marginal zone and the location of its southern boundary. In the Tibetan Plateau, there is significant negative correlation between the area of marginal zone and the location of its southern boundary. For the Loess Plateau and Northeast China, there is notable positive correlation between the area and the location of northern boundary of the ASM marginal zone. Moreover, the location, area and precipitation of the three ASM marginal areas have significant inter-annual and inter-decadal variations. The abnormally less precipitation in the ASM marginal zone is related to the wave train of Eurasia teleconnection pattern over middle-high latitudes. During the period with less precipitation in the ASM marginal zone, the convective activity is weak at low-latitude areas. The anomalous convergence at 200 hPa over the equatorial region on the eastern shore of Africa may lead to the weakening of the ASM and the Somali jet. At 200 hPa, the Asian jet stream is also weaker and more northward. At 500 hPa, under the control of anomalous high pressure over North China, the precipitation caused by the ASM mainly concentrates in South China, and the precipitation in the ASM marginal zone in summer is abnormally less. The synoptic situation of 200 hPa and 500 hPa is opposite from that of ASM marginal zone with more precipitation. The abnormally more precipitation is related to the wave train of the Silk Road pattern in middle-high latitudes over Eurasia. The summer monsoon precipitation in East Asia is characterized as "more in the north and less in the south", and the summer precipitation in the ASM marginal zone is more than the normal level. © 2022, Science Press. All right reserved.
