Data Quality Control And Echo Characteristics Analysis Of NUIST-C Band Dual Linear Polarimetric Doppler Radar

Dual-linear polarimetric Doppler radar is based on the simultaneous transmission and simultaneous receiving of horizontal and vertical polarization wavelength technology which can provide polarimetric radar parameters from clouds and precipitation particles. These polarimetric parameters could reveal not only the shape and the phase of the particles but also the variation of raindrop size distribution. But in actual detecting process, the data quality is vulnerable to ground clutter contamination, system and environment noise, and signal attenuation. In order to present the quality analysis of radar data and make further study of the cloud physical processes and the subtle structure in the cloud, based on a C-band Dual-linear Polarimertic Aperture Coherent Doppler Radar (referred to as NUIST C-Pol radar), the article primarily studied the data and the main research contents and conclusions are as following:1、According to the statistics and analysis of the change of the polarimetric radar parameters with signal-to-noise ratio(SNR) and cross-correction coefficient (ρHV),it is found that SNR and pHV are important factors which affect the quality of polarimetric radar parameters. Only when SNR>24dB and ρHV>0.7, can the quality of the data be stable. But in the short distance the quality of the data is extremely unstable affected by ground clutter contamination. Based on the statistics and analysis results, ground clutter echo can be well identified from the precipitation echo by using radar reflectivity Z and differential reflectivity ZDR and employing matching method.2、According to the natural target method, system error of the differential reflectivity ZDR is calibrated by light rain and dry aggregated snow at the highest elevation of volume scan mode. The results indicate that light rain exhibits lower variability of ZDR than aggregated snow and the variability of ZDR system error is not large which means the radar system is stable.3、On the basis of making quality control on differential propagation phase shift (ΦDP), attenuation radar reflectivity Z and differential reflectivity ZDR are corrected. By comparing the correction results and the S-band radar echo figure at the same time, results are similar to S-band radar which means the correction effect is good.4、By using NUIST C-Pol radar reflectivity and other polarimetric parameters, the article studies the sensitivity to the bright band and the microphysical characteristics of its corresponding hydrometeor. The results reveal that ρHV is the most sensitive to the bright band which presents the bright band characteristics earlier than all the other parameters. Further, the detecting sensitivity to the ρHV is in the bright band and mechanism of data decrease. On the basis of NUIST C-Pol radar polarimetric parameters characteristics, the radar high band at the height of about-16℃ above the bright band is discovered.The results have theoretical and practical value for researching cloud physical characteristics by using Dual-linear polarimetric radar parameters and business operation.