Spatio-temporal distribution characteristics of annual extreme hourly rainfall over central China

Based on the annual maximum hourly rainfall data at 241 national meteorological stations over central China during 1981-2017, we have conducted an analysis of the spatio-temporal distribution characteristics of annual extreme hourly rainfall in central China. The results indicate that the annual extreme hourly rainfall frequency that the thresholds are respectively equal to 30 mm·h^-1 and less than 40 mm·h^-1, equal to 40 mm·h^-1 and less than 50 mm·h^-1 and greater than or equal to 50 mm·h^-1 is higher in Henan and the central and eastern Hubei, while it decreases with the increase of the thresholds in Hunan. The diurnal variation of annual extreme hourly rainfall frequency is characterized by which is most occurred between afternoon and evening, the second between the first midnight and the morning, and is decreased significantly between midnight and the morning, morning and the afternoon. The high mean intensity of annual extreme hourly rainfall is mostly in the central and eastern parts of Henan and Hubei. The high value centers of annual extreme hourly rainfall in Hubei are mainly located in the edge of the Jianghan Plain. The daily peak of annual extreme hourly rainfall frequency mainly occurs from afternoon to evening and after midnight to morning, and it shows obvious regional difference. The annual extreme hourly rainfall frequency with different thresholds all show obvious interannual and interdecadal variation characteristics, which showed a fluctuating reduction trend in the 1980s, a fluctuating growth trend in the 1990s, and low-frequency fluctuation in the early 21st century and then increased in volatility. The diurnal variation of extreme hourly rainfall frequency with different thresholds all show obvious single-peak structure characteristics, and the peak appears around 17:00 BT.