One-minute rain rate distributions in Japan derived from AMeDAS one-hour rain rate data

By examining measured 1-min rain rate data presently available and 1-h rain rate data obtained by AMeDAS (Automated Meteorological Data Acquisition System) in Japan, a simple conversion method of 1-h rain rate data to 1-min rain rate distribution is presented. The prediction accuracy of the method is evaluated, and good accuracy is confirmed. Maps are given of the mean and standard deviation (normalized by the mean value) of 1-min rain rate for 0.01% of time based on AMeDAS data in Japan. Moreover, the effect of a record-breaking heavy rain even on long-term statistics is discussed. Since the method has been successfully applied to various locations in Japan, it can be expected to be applicable to regions of the world where 1-min rain rate data have not yet been available