Temporal and spatial variations of hourly precipitation in Heilongjiang Province in the flood season

Based on hourly precipitation data from 1961 through 2014 in Heilongjiang Province, variations of precipitation, precipitation frequency and precipitation intensity in flood season (May-September) are analyzed. It is found that the precipitation in the flood season was 430.0 mm, the precipitation frequency was 297.2 hours, the precipitation intensity was 1.2-1.7 mm[middot]h-1 and the precipitation intensity had increased obviously. The precipitation change trend and precipitation frequency in most stations were not obvious, but 39% of stations had changed obviously in precipitation intensity. The diurnal variation of precipitation showed a single peak, more than half of the precipitation had concentrated in 11:00-22:00; diurnal variation of precipitation frequency was bimodal, in 00:00-04:00 and 13:00-19:00; the diurnal variation of precipitation intensity also showed a single peak, with high value interval concentrated in 13:00 to 18:00. In the province, short duration precipitation had advantage obviously,