Characteristics of hourly precipitation in Jiangxi

Based on the hourly rain-gauge data from 83 National Weather Stations in Jiangxi area from the period of August 1977 to July 2017, the basic precipitation distribution and diurnal variation characteristics were analyzed. The results are listed below:Firstly, high-value center of annual precipitation hours has a zonal distribution along eastern and western range. There is less annual precipitation hours at plain of Poyang, north area in Jiangxi. Characteristics of hourly precipitation intensities at north and southeast of Jiangxi are:extreme hourly precipitation hours in March and extreme cumulative hourly precipitation in June. The diurnal variation curve of annual hourly precipitation hours has two peaks appearing at 6:00-8:00 and 18:00-20:00. Secondly, the short duration precipitation within 6 hours accounts approximately for 3/4 of the total precipitation. The average hourly duration precipitation last shorter and shorter from south to north, but it has the highest contributing rate for the total precipitation and its spatial distribution rate is decreasing progressively from south to northeast. For those duration precipitation over 6 hours, their contributing rate centers mainly locate at north area and are moving northeastwards with the growth of duration precipitation. Thirdly, hourly precipitation frequency is higher in east than west. Its high-value center moves northward with the ascension of precipitation level. Fourthly, the hourly accumulative precipitation appears mainly at 15:00-18:00 and is presented with short duration precipitation, and the middle duration precipitation (8 hours or so) occur easily in the morning around 7:00-8:00. Finally, the hourly precipitation frequency and accumulative precipitation of eastern part in south have a prominent increasing trend in the past 40 years, and the trend passed 5% significance level test.