An objective approach for comparing radar estimated and rain gauge measured precipitation

Abstract

One of the main concerns with quantitative precipitation estimates (QPE) based on weather radar observations is the extent to which nowcasters should believe them as they rush to issue warnings for dangerous weather phenomena that might endanger human lives and goods. This paper aims to improve QPE by adjusting the mean field bias using rain gauge measurements. Radar data used in this research were supplied from a single polarization S-band Doppler radar, WSR-98D (Weather Surveillance Radar – 98 Doppler), located almost in the centre of Romania, at Bobohalma, and a network consisting of 27 rain gauges within weather stations belonging to the Romanian National Meteorological Administration. The procedure consisted of two main steps: in step one, the reflectivity data were converted into rain rate using the Z–R relationship; in step two, differences between radar data and gauge data were investigated using four objective functions, the ratio between radar data and gauge data, the root-mean-square factor, and Pearson and Spearman correlations. The findings are consistent with previous studies, emphasizing that both the differences and correlations between radar data and rain gauge amounts have local significance rather than general relevance over the studied area.