Abstract: The abnormal changes of summer precipitation tend to produce severe floods and droughts, so grasping the variation characteristics of summer precipitation is particularly important. It will be useful for avoiding disasters of flood and drought. In this paper, based on the daily precipitation during the period 1960-2014 at 23 meteorological stations of Liaoning Province, the summer precipitation and extreme daily rainfall variations and tendencies were analyzed by using the linear trend, moving average and cumulative departure curve analysis methods. Then using wavelet analysis method to analyze the period, and finally using ordinary Kriging interpolation method to analyze the spatial variation of summer precipitation and extreme daily rainfall. The results show that the main period of summer precipitation in Liaoning Province during the 55 years was about 38 years, and the sub period was 22 years. Although the overall trend was declining, the intensity of precipitation was increasing year by year; precipitation trends in 1984, 1992 and 2010 rose significantly. Summer precipitation reduced gradually from the Southeast to the Northwest, and the duration of dry days showed a significant increasing trend. Rain days showed no obvious decrease trend, and there was no obvious increase in the days of heavy rain and rainstorm. The periodic variation of extreme rainfall has the same characteristics, and there were obvious periodic changes of the four indicators of extreme rainfall days at the time scale of 35-40. Heavy rain, rainstorm, heavy rainstorm had the same characteristics of spatial distribution. The change rate of the four indicators of extreme rainfall days had the same banding distribution along the northeast to southwest. The results of this study can provide a theoretical basis for the prediction of climate and effective prevention of flood and drought disasters.

Key words: summer precipitation, extreme rainfall days, spatio-temporal variation, Liaoning Province