Research On Data Quality Control And Precipitation Classification Of X-band Dual Linear Polarization Radar

Due to its smaller size,lower cost and higher spatial resolution,the X-band dual-linear polarization weather radar has obvious advantages in studying the occurrence and development of cloud,precipitation and its micro-physical structure.However,the factors such as the radar system inner noise,environmental noise,ground clutter and so on may will affect the quality of the radar polarimetric data to some extent.In this paper,the experimental data of an X-band dual-linear polarization radar is used to conduct a detailed study,which is mainly presented in two parts:radar data quality control and precipitation particle classification.The main research contents and conclusions are as follows:?1?Firstly,the statistical analysis method is used to study the variation of the reliability of radar polarimetric data with signal-to-noise ratio?SNR?from radar echo.From the statistical result,it's found that when the SNR is lower than a certain threshold,the polarimetric parameter data will show an unstable trend,and its data reliability begins to decline.By determining the threshold size and rejecting the data below this threshold can ensure the quality of radar polarimetric data.?2?In order to remove the influence of non-precipitation targets such as ground clutter on the quality of the radar data used in this paper,we compared distribution characteristics of the polarimetric varibles of precipitation targets and non-precipitation targets,it is found that the spatial texture parameters of the horizontal reflectivity factor?Z_H?and the differential propagation phase(?_DP)can more effectively identify and remove non-precipitation targets.?3?In this paper,the natural target correction method is used to correct the data with system error of the differential reflectivity factor(Z_DR).By comparing with other polarimetric varibles data and analyzing the correction result,it is shown that using light rain as the correction reference object can correct the system error in Z_DRR quickly and relatively effectively.?4?For the phenomenon that the cross-correlation coefficient(?_HV)is abnormally low due to the low signal-to-noise ratio,it is necessary to correct it through the signal-to-noise ratio.The analysis of correction results shows that it has a good correction effect within a certain range,but the correction effect is not ideal for the echo edge which far from the radar center.?5?The differential propagation phase(?_DP)data is processed by moving average filtering method,and the specific differential propagation phase(K_DP)is estimated by the least squares method.Based on this,attenuation correction on the horizontal reflectivity factor?Z_H?and the differential reflectivity factor(Z_DR)which under strong convective weather conditions are showed in this paper.By comparing Z_H data of the C-band doppler weather radar,the corrected result shows that the method named Z_H-K_DPP comprehensive correction can effectively solve the attenuation problem under severe convective weather conditions.?6?After a set of radar data quality control process in this paper,a precipitation particle classfiction system is established based on the fuzzy logic algorithm.Combined with radar radial velocity?Vr?and the theory of polarization parameter characteristics,the rationality of the results obtained by the classfiction system is analyzed.To study the influence of the uncertainty about radar polarimetric varibles on the classfiction results,the sensitivity of the established precipitation particle classfiction system to the polarimetric varibles is analyzed in quantitative way.It is found that among all the polarimetric varibles involved in this system,the system is most sensitive to the uncertainty of the varibles?_HV.The research results and conclusions above are limited in the X-band dual-linear polarization weather radar.The conclusions obtained have certain application value for the research of precipitation particle identification based on fuzzy logic algorithm,especially the analysis on the sensitivity of the established precipitation particle classfiction system in this paper,which can provide the necessary guidance reference for the subsequent study on the precipitation classfiction algorithm.