Effect of multiple scattering on the estimation of rainfall rates using dual-wavelength radar techniques

The effect of multiple scattering on the estimation of rainfall rates using incoherent backscattered power at two frequencies (16 and 34.8 GHz) is analyzed. Simulation of circularly polarized transmissions propagating through homogeneous rain is used to estimate the rainfall rates from echo power levels calculated with and without multiple scattering effects included. The results indicate that in homogeneous rain, the rainfall rate estimated using the multiple scattering calculation is always smaller than that using the conventional radar equation. The difference is significant for heavy rain cases. Since the multiple scattering process may exist in real rain situations, one must be careful in heavy rain cases when interpreting rainfall rates estimated using dual-wavelength algorithms