抄録
The Z-R relationship (Z=aRb) between radar reflectivity factor Z and precipitation rate R has been used for operational radar measurements, but its coefficients (a, b) are known to be highly variable in time and space and also dependent on precipitation types. The Dual-frequency Precipitation Radar (DPR) is expected to instantaneously estimate the 2-moment drop size distribution (DSD) function and to finally derive global maps of (a, b). For this big goal, it is necessary to improve the accuracy of the instantaneous dual-frequency retrieval method. In this study, Mardiana’s method (MA04) is tested with a simulated DPR measurement dataset, and it is found that MA04 has negative bias which corresponds to 40% of the true precipitation rate. While the true equivalent radar reflectivity factor Ze does not change largely along the range, the estimates of Ze by MA04 tend to be smaller at lower range bins. MA04 is modified into three new methods. In the best method, the bias is limited to 18% of the truth.
