The Influence of Raingage Integration Time, on Measured Rainfall-intensity Distribution Functions

Abstract

Rainfall-rate statistics are frequently derived on the basis of raingage recordings having effective integration times of five minutes or more. The conversion of such data to equivalent statistics for an effective integration time of one minute is important in the prediction of microwave system performance. High-resolution tipping-bucket precipitation records for 45 locations in Canada have been analyzed to yield empirical conversion factors appropriate for five- or ten-minute sampling times. Two modes of expression are examined. In one, the ratio of equiprobable one-minute to τ-minute rainfall rates is treated as a function of their probability of occurrence, while in the other it is considered a function of the observed τ-minute rainfall intensity. In each instance the entire Canadian semicontinent could conveniently be divided into three characteristic regions with appropriate raingage correction factors for each region expressed in the form of a power-law over the range of practical interest These results are compared with earlier efforts in Europe, Africa and Australia.