Abstract:To conduct a quantitative study on the sidelobe echoes of the S-band dual-polarization weather radar, based on the plan position indicator (PPI) data of five SAD-type doppler dual-polarization weather radars in Changsha, Chenzhou, Changde, Xiangxi and Huaihua in Hunan Province from 2021 to 2025, 445 sidelobe echo samples were manually screened in this study. On this basis, a numerical matrix was constructed and the values of sidelobe echoes from four types of products were extracted, including horizontal polarization reflectivity (ZH), differential reflectivity (ZDR), correlation coefficient (CC), and specific differential phase (KDP). Statistical analysis was conducted on the spatial distribution characteristics of sidelobe echoes and the average value characteristics of various products. The results show that the sidelobe echoes are evenly distributed in the east-west direction, with fewer echoes in the south and more in the north, in the radar polar coordinate system. The areas with the highest occurrence frequency of sidelobe echoes are concentrated in the range from the radar static cone area to 100 km and at the melting layer height of 3.0-4.0 km. The sidelobe echoes mainly appear within the range of ±6 km in radial distance from the high echo core and 4°-40° in azimuth, and the highest frequency is located at the same radial distance as the high echo core and 12°-13° azimuth on the lateral side. The sidelobe echoes have significant low-value characteristics in radar polarization parameters. 75% of the sidelobe echoes exhibit ZH ≤ 8.0 dBz, ZDR ≤ 0.56 dB, and CC ≤ 0.92, with ZH most frequently occurring in 0-5 dBz, ZDR in 0-1 dB, and CC in 0.9-1.0. Although the low values of polarimetric radar variables in sidelobe echoes are distinct, 26.0% of the samples with azimuthal spans ≥30° exhibit a terminal ZDR ≥ 5 dB. The research results are conducive to improving the identification efficiency of sidelobe echoes and are a valuable basis for future’s automatic identification of sidelobe echoes.