Characteristics of spring and summer rainfalls in Anshan from 1951 to 2004

Based on spring and summer rainfalls data in Anshan from 1951 to 2004,the characteristics of spring and summer rainfalls were analyzed with linear trend estimation method and wavelet analysis method.The results showed that spring rainfall in Anshan displayed an upward trend with 2 mm/10a,while summer rainfall was a downward trend with 5 mm/10a.The instabilities of spring and summer rainfalls increased since the 1980s.There were periodical changes with 4-6 years and 16-18 years in spring rainfall variation and with 6-8 years and 18-20 years in summer rainfall variation.The different periodical changes played dominant roles in different periods.