Change of sunshine duration in Lanzhou from 1961 to 2003

Using the data of monthly sunshine duration and precipitation over Lanzhou from 1961 to 2003,the trend variation of the sunshine duration was analyzed by using linear trend analysis.Main results were as follows:(1)On an average in Lanzhou,the annual sunshine duration showed a significant decreasing tendency during recent 43 years with a decreasing rate of 78.4 h/10a.The decreasing trend occurred,especially in winter.(2)In the 1960s and1970s,the sunshine durations were more sufficient in spring and summer,while lower in autumn and winter.The sunshine duration of positive anomaly occurred in all seasons in the 1980s,especially in spring and winter.But to the contrary in the 1990s,the sunshine durations were higher in all seasons,especially in spring and summer.(3)Also,the annual sunshine durations were more anomalous years in the 1960s,whereas less anomalous years in the 1980s.(4)Results indicated that the decrease of sunshine duration was connected with precipitation.