Comparisons of three-dimensional reflectivity and precipitation rate from GPM dual-frequency precipitation radar and ground dual-polarization radar

Abstract

Dual-frequency precipitation radar (DPR) on the Global Precipitation Measurement Mission (GPM) core satellite provides three-dimensional (3D) precipitation estimates over the globe. Ground radars (GRs) can quantitatively measure instantaneous precipitation distributions at multiple elevation angles. This study compares the reflectivity and precipitation rate fields from DPR and ground dual-polarization radar using the geometry matching method for different hydrometeor classes. In the reflectivity comparison, the non-Rayleigh effect was corrected beforehand accounting for different hydrometeor types. The results showed good agreement for most hydrometeors with correlations exceeding 0.85. Bias mainly occurs in dry snow and ice crystals. The precipitation rate comparison was split into two classes of liquid and non-liquid samples. Optimally combined polarimetric rainfall estimates were used as the GR liquid precipitation values, whereas multiple R(Z) relationships were utilized for non-liquid hydrometeors. Compared to convective rain, stratiform precipitation shows better consistency with the GR estimates, with the correlation reaching 0.73 and the mean bias reaching −0.47 mm/h. Owing to the rapid variation in the DSD parameter of Dm with distance in convective precipitation, the rainfall discrepancy was greater for convective precipitation. The precipitation rate comparisons for dry snow, wet snow, and graupel showed good consistency, with mean biases within 0.6 mm/h. The deviation increased significantly as the radar reflectivity increased, and large particles contributed to significant inconsistency.