Radar calibration using polarimetric observations with rain attenuation correction

While radar polarimetry has shown improvements in data quality, the accuracy in estimating rainfall rate remains limited by the calibration especially for reflectivity at horizontal polarization (Z_H) of the radar. Calibration of Z_H can be achieved using the relationship between Z_H, differential reflectivity (Z_DR), and specific differential propagation phase (K_DP). However, Z_DR and Z_H measurements can be decreased by rain attenuation along the radial direction especially for radars operating at C-band or higher frequencies. Thus, in this study, an attenuation correction is made for the two measurements before the calculation of theoretical K_DP, which is then integrated in the radial direction to yield a theoretical differential propagation phase ( Φ_DP). Differences between theoretical and observed Φ_DP at the end of rain path are attributable to the bias in Z_H measurements. Once the system bias in Z_H measurements is determined, this method can also estimate attenuation due to both the wet radome and heavy rainfall simultaneously in Z_DR and Z_H measurements.