Validation and Evaluation of Ocean Calibration Accuracy of FY-3G Precipitation Measurement Radar
FY-3G precipitation satellite launched in April 2023 is the first dedicated precipitation measurement satellite in China.The dual-frequency precipitation measurement radar(PMR)is the core instrument on the satellite.Because the backscattering performance of the vast ocean area is relatively stable,the calibra-tion accuracy of the on-orbit radar can be tested by studying the backscattering cross-section of the sea sur-face.FY-3G PMR level 1 data in July 2023 and GPM DPR(global precipitation measurement,dual-fre-quency precipitation radar)level 2A data are used to analyze the mean value and mean square error of the global sea surface backscattering cross section under no-rain conditions to evaluate the radar performance.At the same time,the theoretical model of ocean surface backscattering is studied to simulate the sea sur-face backscattering cross-section under the condition of no rain,and the sea surface backscattering cross-section is compared with the actual radar measurement,so as to realize the preliminary evaluation of FY-3G PMR calibration accuracy.Furthermore,the accuracy of FY-3G PMR calibration is evaluated by the ocean calibration test results of GPM DPR data.Test results of ocean calibration accuracy show that when the incidence angle of FY-3G PMR Ku-band is less than 15°,the deviation between the observed value and the model simulation value is small.The deviation of FY-3G PMR ranges from 1.65 to 2.73 dB,while the standard deviation ranges from 0.74 to 1.82 dB.The deviation of FY-3G PMR Ka-band at an 18° incidence is less than 0.27 dB,and the standard deviation of the deviation is 3.49 dB.The calibration deviation of FY-3G PMR and GPM DPR is relatively constant,with the difference is primarily attributed to the back-scattering statistical characteristics of the data itself.The stability of the backscattering data of FY-3G PMR Ku-and Ka-band sea surfaces at each incidence angle is comparable to that of GPM DPR.Gas attenu-ation is not considered at the moment.In the future,the impact of gas attenuation on the Ku-and Ka-band ocean calibration accuracy validation will be further evaluated,and the systematic deviation of FY-3G PMR will be corrected.
万方数据
维普
