Abstract:Based on the principle of threshold method with daily precipitation data from 1980 to 2009, observed by 20 rain gauges over the Yangtze Huaihe region, a investigation is conducted on the characteristics of precipitation over the Yangtze Huaihe region, with emphasis on the highly correlative relation between the monthly mean daily rainfall and the ratio of the number of rainy days with rainfall exceeding a certain threshold to the number of days of the month when the rainfall thresholds being 01, 10, 50, 100, 240, and 480 mm/d, respectively. A high correlation is found between the monthly mean daily rainfall and the ratio of the number of rainy days with rainfall exceeding a certain threshold to the number of days of the month. The correlation coefficient varies with rainfall thresholds, higher than 097 for all 20 stations, peaking at a threshold of 240 mm/d. The rain rate and fractional rain day were nonlinearly related at low rain rate thresholds. The threshold method can be applied widely, for examples, to achieve a better understanding of the forming mechanics of precipitation, to seek better algorithms for the estimation of precipitation, to develop better parameterization schemes for numerical forecasting models, and to validate the outputs of various numerical weather models, and so on.