Abstract:Based on the daily rainfall data of 50 observational stations in Liaoning Province during 1961-2012, and NCEP/NCAR daily reanalysis data, the large scale circulation characteristics of Liaoning rainfall and the causes of heavy precipitation during early summer in 2012 were analyzed. The results show that the cooperation of large scale circulation system in different heights of troposphere in East Asia is the main cause for precipitation anomaly in Liaoning in early summer. The circulation features of the four main precipitation processes in Liaoning in early summer are almost the same. Upper level jet stream shows the phenomenon of branch at 200 hPa over the west of Northeast. Two ridges and two troughs control Asia mid latitude regions at 500 hPa, and one trough controls the Northeast, corresponding to negative geopotential height anomaly. 850 hPa wind field and the 1000-300 hPa moisture field show the cyclonic circulation feature over the Northeast. In rainy years, upper level jet stream presents the phenomenon of branch at 200 hPa, and the strength of subtropical westerly jet is stronger than normal years. Two ridges and one trough control Asian mid latitude regions at 500 hPa, and the Northeast is controlled by trough, corresponding to negative geopotential height anomaly. 850 hPa wind field has the cyclonic circulation feature over the Northeast, which indicates that a deep low pressure system controls the Northeast, from low to high levels in troposphere. Circulation features of every layer show that the deep Northeast cold vortex is the leading impact factor of anomalous rainfall over Liaoning Province in early summer in 2012.