Validation of X-Band Multiparameter Phased-Array Weather Radar by Comparing Data from Doppler Weather Radar with a Parabolic Dish Antenna

The multiparameter phased-array weather radar (MP-PAWR) was the first dual-polarized phased-array weather radar to be commissioned in Japan (2017). When conducting a volume scan, the MP-PAWR respectively uses electronic and mechanical scanning in the elevation and azimuth angles to achieve rapid scanning and high-density observations. Although the effectiveness of the MP-PAWRhas been demonstrated in case studies, its observation accuracy is yet to be quantitatively analyzed. Therefore, this study compared data of MP-PAWR with that of an operational dualpolarized weather radar with a parabolic-type antenna [X-band multiparameter (X-MP) radar] using 2 347 097 data samples obtained over 14 h. The results showed that the observation accuracy of the MP-PAWR was approximately the same as that of the X-MP radar at low elevations. The correlations of observational parameters (radar reflectivity factor, differential resistivity, specific differential phase, and Doppler velocity) between the MP-PAWR and X-MP radar ranged from 0.77 to 0.99 when MP-PAWR data were recorded within 15 s of the X-MP radar observations. The correlation between the observational parameters of the two radars decreased as the observation time difference between the X-MP radar and MP-PAWR increased. In particular, the correlation coefficients between the specific differential phase and the differential reflectivity were considerably lower than the single-polarization parameter at observation time difference of 240-300 s. By providing high-frequency and high-density dual-polarization observations, the MP-PAWR can contribute to rainfall prediction in Japan and reduce the damage caused by localized, rapidly developing cumulonimbus clouds.