The characteristics of diurnal variations in amount，frequency and intensity of hourly heavy precipitation in flood seasons

including the first and second flood seasons

and the spatial distribution were studied based on the hourly precipitation data from 32 meteorological observational stations in Guangdong during 1961-2014. The results show that the peak of hourly heavy precipitation amount and frequency occurred at 16:00

the second peak occurred at 08:00

but the intensity diurnal variations of heavy precipitation were not obvious. There were regional differences at the peak of hourly heavy precipitation amount and frequency in flood seasons. The peak occurred in the morning (06:00 to 09:00) and at noon (10:00 to 13:00) in southern coastal areas

in the afternoon (14:00 to 20:00) in Leizhou Peninsula and the rest of Guangdong. The peak of hourly heavy precipitation intensity occurred on day and night. There were three high-value centers of the peaking amplitudes of hourly heavy precipitation amount during the first and second flood seasons

located in western Lauding

eastern Wuhua

northern Nanxiong and Lianpin. The peaking amplitudes of hourly heavy precipitation frequency showed increasing trend from coastal areas to inland

but there was little regional difference of the peaking amplitudes of hourly heavy precipitation intensity.