Abstract: Based on the precipitation data from 54 meteorological stations in Liaoning province from 1981 to 2015,the spatial and temporal characteristics of summer precipitation extremes were analyzed using climatic trend coefficient,Morlet wavelet analysis and Mann-Kendall sudden change analysis and other climatic statistical methods.The results show that the larger values of the threshold of summer precipitation extremes occur in the coastal areas in the southwestern part of Liaoning province,the northern parts of the Bohai Sea and the Yellow Sea and in Dalian urban district.The smaller values occur in the western and eastern mountain areas of Liaoning province.The spatial distribution characteristics of extreme precipitation intensity are similar to those of the precipitation threshold.Basically,the distribution characteristics of extreme precipitation frequencies for different precipitation durations are same.There is not a clear trend in the long-term change of it.It mainly shows an inter-annual variation,with 3,5 and 8 years' change periods.The frequency of extreme precipitation is higher in the eastern mountain areas and lower in the coastal area of the Bohai and Chaoyang city.The spatial distribution of precipitation amount extremes within 24 h,12 h,6 h,3 h and 1 h in summer is particularly uneven,and the corresponding ratios of the maximum to minimum of extreme values are 1.2,1.6,1.6,2.4 and 1.8,respectively.The maximum length of extreme wet period occurs in Xinbin area and lasts about 11.3 days,and that of extreme dry period occurs in the Dashiqiao area and is persistent 24.3 days.

Key words: Cycles of precipitation, Abrupt change, Extreme wet spell, Extreme dry spell