Interdecadal and Interannual Variabilities of Summer Rainfall in Shandong Province

Based on the 7-station observation in Shandong Province and other datasets, interdecadal and interannual variabilities of summer rainfall in Shandong Province are analyzed.The result showed that summer rainfall underwent a pronounced interdecadal variability, with more rainfall from 1950s to the late 1970s and less rainfall from the late 1970s to the beginning of the 21st century.After the late 1970s, there occurred a transition for the Pacific decadal oscillation from a negative phase to a positive one, thus leading to a decreased East Asian summer monsoon and less summer rainfall in Shandong Province.In addition, the decadal background plays a role in interannual variability of summer rainfall.During 1951-1977, there was a significantly negative correlation between summer rainfall and sea surface temperature in the tropical central Pacific(Niño4 region).After 1978, however, this relation decreased dramatically.It is also noted that summer rainfall in Shandong Province seems to have entered a more rainfall period along with a transition of PDO from a positive phase to a negative one after 2003.