An improved algorithm in unipolar weather radar calibration for rainfall estimation

Weather unipolar ground-based radar estimation can experience momentous changes by using other effective parameters such as distance from radar, altitudes and rainfall time duration that directly compromise the accuracy of the hydrometeorology applications. These radar measurements however, need to be calibrated for more accurate rainfall estimation. In addition to the radar-rainfall (Z-R) relationship, this is a pragmatic approach based on careful analyses of other parameters. This article introduces a new calibration approach using altitude parameters and time-stepwise processing of reflectivity-rainfall (Z-R) rate relationship. This research leads to introduce a new effective parameter and generate two new empirical coefficients in radar-rainfall relationship. Two consecutive years unipolar ground-based radar data sets with 190 occurrences of rainfall from 43 stations in calibration window of 3 h; and the corresponding rainfall measured from registered rain gauges were used in this study. The results indicated that radar-rainfall relationship Z = AR(b) is better improvised with altitudes effect (H) and empirical coefficient (c), such that Z = AR(b)H(c). It therefore is concluded that the use of other effective parameters (distance from radar, altitudes and rainfall time duration) leads to optimum accuracy of Z-R relationship.