Research On The Data Quality Control Method Of X-band Dual-polarization Radar

The topic of this article is to analyze and solve the problem of X-band dual polarization radar observation data quality.X-band dual-polarization radars were deployed by the Beijing Meteorological Bureau and the Foshan Meteorological Bureau.Its observation data of weak and strong precipitation process from May to August in2016 was obtained to study the data quality control method of X-band dual linear polarization radar.The article uses the characteristics of polarization parameters that uniformed in nature and slowly changed with time and space in the process of weak rainfall and selects the observation data of weak precipitation process in Beijing and Foshan.Through the method of accumulating in radial or azimuth by taking a long-term observation,this paper analyzes the accuracy of polarization parameter measurement that affected by the ground,lightning rod,rotation and pitching joints and puts forward to the corresponding quality control method and the evaluation of results.In addition,in order to analyze the intensity attenuation about the X-band dual polarization radar in heavy rain.We need to select the echo-pair data at the same time and close distance between the SA radar and the X-band dual polarization radar.We use the differential propagation phase correction method based on S-band single polarization radar,to experimentally fit the optimal attenuation coefficient,the system deviation,and the value of radome water film loss of X-band dual polarization radar,and puts forward to the comprehensive correction method and progress of testing.The specific results are as follows:?1?By accumulating the observations in the radial direction or the azimuth,we analyze the influence of each polarization parameter on the lightning rod,the rotating and pitching joints and the ground objects,and find that the orientation and amplitude of each lightning protection effect for each polarization parameter are approximately the same.In the azimuth range of±15°centered on the lightning rod,Z_DR increases by about 0.4¹.5 dB,Z decreases by about 1² dBZ,and?_hv decreases by<0.01,and both of them reach the extreme value at the center of the lightning rod.An abnormality in the rotating joint causes the Z_DR to change unevenly in the horizontal direction,and the abnormality of the pitch joint causes the Z_DR to have a large difference between the high and low elevation angles.The Z_DR,?_hv and?_DP at the distance of the ground echo are more sensitive than Z, where?_hv is less than 0.85 and Z_DR is lower than minus 1 dB.?2?According to the variation of the polarization parameters along the azimuth,the correction curve can be used to make the Z_DR increase and the?_hv decrease in the azimuth affected by the lightning rod to be more continuous with the surrounding azimuth echo,and the Z_DR value after the rotation joint is removed is 0 dB.Nearby, it is also closer to the light rain feature.?3?The average value of the attenuation coefficient experimentally fitted by the precipitation process of Beijing on July 20,2016 is 0.26 dB?°?^-1,and the variation range of the attenuation coefficient value is from 0.20 dB?°?^-11 to 0.31 dB?°?^-1.In addition,the measured value of the water film loss of the radome varies within the theoretical range.Generally,the water film loss of the radome is small compared with the rain zone in the case of heavy precipitation?the difference is one order of magnitude?.The system deviation of the X-band radar reflectivity also fluctuates with time.The average system deviation of BJXCP station and BJXTZ station is 0dB,BJXSY is 2 dB and BJXFS is-1dB.?4?The rain zone attenuation correction results using dynamic,static and foreign fixed coefficients show that the X-band radar echo intensity quality can be significantly improved?the improvement level of MAD,CC and SD is more than 40%?.Among these methods,the dynamic method can better complete the comprehensive correction of the real-time observation reflectivity when the precipitation is strong, and the static method can have a better correction effect on the short-term heavy precipitation data that has occurred.However,if the foreign attenuation coefficient is used as the rain zone attenuation correction,excessive correction or insufficient correction will occur,which will affect the correction effect.