## 3 Instruments and Data
process is affected by large particles (both biological and precipitation), it will directly produce a missing measurement rather than an erroneous value. The wind measurement products of Doppler wind lidar (Windcube 100s, Loosphere, Saclay, France) have a spatial resolution of 25 m with a temporal resolution of 20 s. Therefore, using Doppler wind lidar instead of radiosonde is a reliable way to measure wind field information in the real atmosphere. Thirdly, in order to confirm the actual weather conditions, both the Himawari-8 satellite observations and the ERA5 reanalysis products were utilized. The Himawari-8 satellites are operated by Himawari Operation Enterprise Corporation (HOPE, Tokyo, Japan), which was established under the Japan Meteorological Agency (JMA) Private Finance Initiative project. Observation data are transmitted through HOPE to JMA, which processes the information and disseminates products to users. The Himawari-8 satellite has facilitated the undertaking of a multitude of research projects, yielding a substantial corpus of findings. ERA5 has been the fifth generation ECMWF reanalysis for the global climate and weather for the past 8 decades. Data are available from 1940 onwards. ERA5 replaces the ERA-Interim reanalysis. Reanalysis combines model data with observations from across the world into a globally complete and consistent dataset using the laws of physics. ERA5 is a state-of-the-art reanalysis product with extensive temporal coverage, high spatial and temporal resolution, and a wide range of applications in weather analysis. The operations of all of these meteorological observation devices (except Himawari-8) are under the supervision of the China Meteorological Administration (CMA). The weather radar is also calibrated weekly and monthly according to the technical regulations of the CMA, which includes system internal calibration, receiving link calibration, rotary joint calibration, and others. Although CINRAD data have been widely used internationally and have produced a series of research results [32; 33; 34; 35], a small number of scholars are still  
Figure 2: Location of weather radar and the vicinity topography. The diamond denotes the CINRAD/SA radar. The squares denote the X-band radar. The radar stations marked in red are also equipped with wind lidars, while those labelled in black are not. uncertain about the reliability of the device. Therefore, the rationality of CINRAD data is briefly analyzed for a precipitation process. A precipitation process was selected on 15 May to demonstrate the reliability of radar data. As the process falls within the middle period of our clear-air echo research sample set, it can be considered to represent the data accuracy during the research period. Moreover, the precipitation intensity is relatively low, comparable to light rain, which allows for the straightforward analysis of radar polarization distribution characteristics during this precipitation process. In Figure 3, both the precipitation and non-precipitation echoes observed by Beijing CINRAD/SA radar are shown, and there are clear differences in the dual-polarization products between the precipitation and non-precipitation echoes. The correlation coefficient shows a clear delineation between precipitation and non-precipitation signals, with the precipitation echo having a much higher value. Similarly, differential phase and differential reflectivity also clearly identify the characteristics of precipitation and non-precipitation signals. Due to the weak reflectivity factor of the non-precipitation echoes, histograms are generated using the dual-polarization products for echoes with reflectivity factors greater than 20 dBZ, as shown in Figure 4. As expected, the correlation coefficient is approximately 0.98 for precipitation signals. The histogram of differential reflectivity shows characteristic weather values near 1 dB. The differential phase values are close to the calibration standard of 45\({}^{\circ}\), and the specific differential phase is mainly between 0 and 0.1.