地基35 GHz测云雷达回波强度的衰减订正研究

The attenuation correction for a 35 GHz ground-based cloud radar

为了订正大气和云对毫米波雷达信号的衰减,选取了层状云、降水性层状云及对流云个例,进行了衰减订正试验.根据雷达反射率因子Z与衰减系数k的经验关系,采用分级逐库订正法进行订正.结果表明,对于回波强度比较弱的层状云来说,订正后数据可靠性较高;对于降水回波来说,雨水及传播路径中的丰富水汽都会造成毫米波信号的严重衰减,因此降水云的衰减订正难度大.经过订正后,虽然还存在误差,但对毫米波雷达数据的质量有明显改善.

To correct the attenuation of radar echo at millimeter-wave band, stratus cloud, precipitating stratus cloud and convective cloud echo data were chosen as sample for the test. Method of bin-by-bin correction in the groups was used according to the empirical relationship between radar reflectivity factor Z and attenuation coefficient k. The results show that, in cases of stratus clouds with weak echo, the corrections are minor and these echoes are almost right. On the contrary, in case of rainfall, both water droplets and rich water vapor along the ray path will cause strong attenuation, and it is difficult to carry out the correction. After attenuation correction, the quality of millimeter wavelength radar data is definitely improved though difference is still existed.