Interdecadal increase of summer precipitation in North China in the early 2010s and its association with atmospheric circulation anomalies

North China is a major agricultural and industrial production area in China with population aggregation, where drought and flood disasters will cause serious economic losses and environmental impact. Based on monthly observation data of summer precipitation in the past 61 years (1961—2021), an interdecadal variation is found in summer precipitation over North China in the early 2010s, that is, it experienced a change from dry to wet around 2011/2012. Differences in the associated atmospheric circulation over North China between the dry and wet periods are further analyzed by selecting 1999—2011/2012—2021 as the dry/wet period respectively. The results show that the change in East Asian summer monsoon bears little to the interdecadal change from dry to wet in North China, which is different from the interdecadal changes in the late 1970s and the late 1990s. During the wet period of 2011—2021, the circulations in the mid-lower troposphere show cyclonic circulation anomalies over Mongolia-Northeast China. The northerly winds on the west side of the cyclone transport cold air from the high latitudes to North China, which is conducive to the intersection of cold and warm air in the area. In the upper troposphere, the cyclone circulation anomalies over the Mongolia-Baikal Lake result in the enhancement of the East Asian westerly jet. The diagnosis of vorticity equation shows that horizontal advection term of relative vorticity significantly contributes to the northward and eastward extension of the jet, which is favorable for the enhancement of upward motion in North China. Meanwhile, the pseudo-equivalent potential temperature increases and its vertical variation enhances, indicating that the atmosphere over North China is warmer and wetter at low level with more unstable atmospheric stratification, which is also favorable for the development of anomaly upward motion. The changes in dynamic and thermal conditions lead to a significant increase in summer precipitation over North China from 2012 to 2021.