Trends of summer precipitation and its regional characteristics in Liaoning Province,China during 1961-2004

This paper presents a study on the temporal and spatial trends of the summer precipitation(Jun-Aug),using trend coefficient,Rotated Empirical Orthogonal Function(REOF),and running standard deviation,based on monthly precipitation from 39 representative weather stations in Liaoning Province,China,during 1961-2004.The results indicate that the long-term overall trend of the summer precipitation in Liaoning decreased at a rate of 14mm per 10 years.Furthermore,the trends were varied with time.Positive trends were detected from 1960s to mid 1970s,in mid 1980s and mid 1990s.Negative trends were observed form mid 1970s to early 1980s,from 1980s to early 1990s,as well as from late 1990s to present.Based on the rotated EOF,this study identified three homogenous regions of summer precipitation:(1) central Liaoning,Panjin,Fushun and Yingkou;(2) west of Liao River;and(3) southeastern Liaoning.The summer precipitation in the southeastern Liaoning region decreased with a faster rate of 34mm per 10 years.