Derivation of regression coefficients and conversion factors for 1-minute rain rate statistics in a tropical environment

Abstract

An important characteristic of rainfall levels at a particular place is the statistical distribution of rainfall rate. In this paper, 1-minute, 5-minute and 30-minute integration time rainfall data were obtained from three different weather stations in Physics Department, Federal University of Technology, Minna, North Central Nigeria. The aim is to derive regression coefficients and conversion factors for predicting rainfall rate of 1-minute integration time from rainfall rates of other integration times. This was achieved by employing Segal, Flavin and Watson rain rate models. The results obtained revealed that there is a power law relationship between 1-minute rain rate (R1) and the equiprobable 5-minute rain rate (R5); and between 1-minute rain rate (R1) and the equiprobable 30-minute rain rate (R30). Also, it was observed that the values of regression coefficients a and b, and conversion factors Ce and CR derived in Minna were different from values derived at other locations in and outside Nigeria when comparisons were made. These discrepancies are attributed to the differences in climatic conditions between the regions among other factors. Therefore, these findings have further corroborated claims by earlier researchers that different regression coefficients and conversion factors are needed for different locations for 1-minute rain rate conversion.