Climatology and changes of hourly precipitation with various intensities in Yunnan Province from 1982 to 2016

Based on the hourly precipitation data from 67 national-level weather stations over Yunnan Province from 1982 to 2016, three hourly-precipitation types with varying intensities, namely, the extreme (above the 95th percentile), heavy (between the 80th and 95th percentile), and moderate-to-weak (below the 80th percentile) hourly precipitation types, are defined using the percentile method, and their 35 year climatological means and long-term changes are investigated. Results are as follows. (1) The high-value center of mean precipitation intensity is located in southern Yunnan and the high-value center of occurrence frequency is in the northwest, which correspond to the areas with the highest and second highest annual precipitation amount, respectively. Precipitation in Yunnan Province is produced mainly in summer and autumn. Meanwhile, there is a spring rainy season in northwest Yunnan that is characterized by high occurrence frequency, strong intensity, and large precipitation amount during February to April. (2) The thresholds of both the extreme and the heavy hourly precipitation types decrease progressively from south to north and from west to east. (3) In the past 35 year, the annual amount and occurrence frequency of each precipitation type in most areas of the province show a decreasing trend, being most evident in autumn, which weakens with the precipitation intensity. In contrast, the hourly precipitation intensity presents an upward trend that is statistically significant in the extreme precipitation type during summer and autumn.