Influence of non-uniform radar beam filling on attenuation correction at C- and X-band

At short wavelengths, the attenuation of the radar signal due to precipitation along its path constitutes a major source of error for radar rainfall estimation. The different techniques developed to correct for this attenuation generally assume that the radar sampling volumes are homogeneously filled by rainfall. However, rainfall is highly variable over a large range of scales, and the influence of the heterogeneity within the radar sampling volume, also known as non-uniform beam filling (NUBF), needs to be quantified. A recently developed stochastic simulator of range profiles of raindrop size distributions (DSD) provides a controlled experiment framework to quantitatively investigate the influence of NUBF on attenuation correction. Using a Monte Carlo approach, we generate 1000 profiles of 30 km long, with an initial resolution of 25 m. By averaging the profiles, the resolution is progressively decreased to 5 km. Two attenuation correction algorithms are applied to the generated attenuated profiles, and the evolution of their performance with the decreasing resolution is quantified. In this work, we focus on incoherent non-polarimetric single-frequency groundbased radar systems, and NUBF only concerns the radial heterogeneity within the radar sampling volume. Section 2 is devoted to the description of the DSD simulator. In Section 3, the two attenuation correction algorithms are presented. The results are described and commented in Section 4.