Diurnal cycle of summer rainfall in Shandong of eastern China

Using the hourly precipitation data at 123 gauge stations of Shandong province in eastern China during 1996-2008, the authors examine the spatial distribution of summer (June-July-August) precipitation amount (PA), precipitation intensity (PI), and precipitation frequency (PF) and their diurnal cycles. The results show that the diurnal peak of PA decreases from the southeastern to northwestern Shandong and mainly appears in the early morning and afternoon. The large diurnal peak of PA mainly appears in a large area from the hilly areas of southern Shandong to the eastern coasts. Large diurnal peak of PI mainly appears along the lower reaches of the Yellow River in northern Shandong. The diurnal peak of PF also decreases from southeastern to northwestern Shandong. The diurnal cycles of PA and PI have two peaks and they occur in the early morning and the afternoon, respectively. The diurnal cycle of PF has one peak in the morning. Large PA values show a southwestward time delay over northwestern Shandong, a northeastward time delay over central and southeastern Shandong in the afternoon, and a southeastward time delay over central and southeastern Shandong in the morning. Moreover, they also show a time delay from the central mountains of Shandong to its adjacent areas in the afternoon. When hourly precipitation is weaker, the diurnal cycles of PA and PF show a two-peak feature. With following the increase of hourly precipitation, the diurnal peak number also tends to increase. (c) 2013 The Authors. International Journal of Climatology published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society.