Abstract: Based on the daily precipitation observations in Dalian and the NCEP/NCAR (National Centers for Environmental Prediction/National Center for Atmospheric Research) monthly mean reanalysis data from 1971 to 2016,diagnostic analysis of causes of anomalous more precipitation over Dalian during July of 2013 was conducted.The results show that a "two ridge and one trough" circulation pattern retains in the middle and high latitudes over the Eurasian Continent.The high pressure over the Ural Mountains and Okhotsk Sea is abnormally stronger,and the low trough maintains steadily near the Baikal Lake,which results in the frequent movements of cold airs to the south.Meanwhile,the more northern and stronger subtropical westerly jets,the more western and northern Western Pacific Subtropical High,and the stronger summer monsoon over the East Asia favor the transport of warm,moist water vapor to Dalian from the Bay of Bengal,the South China Sea and the northwest Pacific Ocean,along the periphery of the subtropical high.Warm and cold airs converge over Dalian,and an abnormal converging area of water vapor formed,leading to anomalous more precipitation in Dalian.Moreover,a high energy tongue,the unstable atmospheric stratification,abnormally stronger upward motions,and the divergence at upper levels and convergence in lower levels provide favorable thermal and dynamic conditions for the anomalous rainfall in Dalian area.

Key words: Precipitation, Circulation anomaly, Water vapor convergence, High energy tongue, Unstable stratification