Abstract: According to the precipitation data of 21 meteorological stations from 1961 to 2017 in Shandong Province, we examined the spatial and temporal variations of yearly and seasonal precipitation and rainy days in Shandong Province via linear regression, spatial interpolation, moving average and wavelet analysis. Results unveiled that the precipitation and rainy days displayed a latitudinal zonal decline from south to north and a longitude zonal decrease from east to west in Shandong Province, with the high-value centering in the Mount-Tai area. The spatial distribution of rainy days in spring and summer was similar to that of annual rainy days, and the number of rainy days in winter distributed in a Northeast-Southwest decreasing trend. The number of annual rainy days dropped significantly at a rate of -2.16 d/(10 a) (passing 95% significance test), while the annual precipitation declined at a rate of -16.28 mm/(10 a), both in periodic change of about 17 a. The precipitation in spring showed a slight increase trend, which was opposite to the trend of rainy days. The precipitation and rainy days in the other three seasons were in negative trend; and particularly, the trend coefficient of precipitation and rainy days in summer passed 95% significance test. The negative trend of rainy days was stronger than precipitation and had a wider spatial range both on annual scale and on seasonal scale. The research findings provide a reasonable basis for water resources planning and utilization in Shandong.

Key words: precipitation, rainy days, trend coefficient, spatiotemporal characteristics, Shandong Province