The Comparison of Z-R Relation Methods on Convective and Stratiform Rain of Quantitative Precipitation Estimation (QPE) in East Java Area

Abstract

AbstractQPE can be calculated using the Z-R relation algorithm by empirical equations between weather radar reflectivity and rainfall. The application of various Z-R relations has been widely carried out in Indonesia. However, there is still little research on the most suitable ones to be applied, especially regarding the convective and stratiform rain types. This study aims to compare several Z-R relations, namely Rosenfeld Tropical, Fujiwara, and Arida et al., to determine the most effective algorithm in some areas of East Java. SRI product is accumulated into PAC and RIH to be validated at each rain gauge location during season periods and by considering the radius of the weather radar. The results show that the best Z-R relation algorithm is Arida et al., with the highest correlation value 0.76 and the lowest RMSE 0.82 mm/hr, followed by Fujiwara then Rosenfeld Tropical with the highest correlation values 0.71 and 0.67 and the lowest RMSE 1.2 mm/hr and 2.09 mm/hr. The correlation tends to be higher during DJF as the peak period of the rainy season, and RMSE tends to be lower in the stratiform rain. The strongest correlation and the smallest RMSE occur in the closest radius within 50 km from the weather radar location.KeywordsQPEZ-R relationRain