Temporal and Spatial Distributions of the Diurnal Cycle of Summer Precipitation over North China

Based on the merged hourly precipitation product at 0.1° resolution in China during 2008-2014, the diurnal variation of precipitation over North China in the summer has been revealed in this study. The precipitation data is derived from hourly precipitation observed at automatic weather stations (AWS) in China and retrievals from CMORPHCPC (Climate Prediction Center) morphing technique satellite data. The results show that the diurnal cycles of precipitation amount and precipitation frequency over northern China in the summer have two peaks that occur in the early morning and late afternoon, respectively. Diurnal variations of precipitation over various regions with different terrains differ from each other. The diurnal cycles of precipitation amount and precipitation frequency have a single peak (two diurnal peaks) over the mountainous areas in northern Hebei and the northern part of the North China Plain (other areas). Diurnal peaks of precipitation amount and precipitation frequency both occur around 1800 BT (Beijing time) and display an obvious consistency over the areas to the west of Taihang Mountains. Over the plains and coastal areas in eastern North China, the amplitude of the morning peak is larger than that of the late afternoon peak. Analysis of the contribution of precipitation with different duration time to the total precipitation indicates that short-duration (long-duration) precipitation has a greater impact on the precipitation peak in late afternoon (morning). The precipitation with the intensity of 0.1-10 mm h^-1 makes greater contribution to the total precipitation amount compared to that with the intensity over 10 mm h^-1. The number of diurnal peaks increases with the increase in precipitation intensity.