Quantitative analysis of weather radar attenuation correction accuracy

At short wavelengths, especially X- and C-band, the radar signal is attenuated by the precipitation along its path. This constitutes a major source of error for radar rainfall estimation, in particular for intense precipitation. A recently developed stochastic simulator of range profiles of raindrop size distributions (DSD) provides a controlled experiment framework to investigate the accuracy and robustness of attenuation correction algorithms (Berne and Uijlenhoet, 2005). The work presented here focuses on the quantification of the influence of uncertainties concerning radar calibration, the parameterization of power law relations between the integral variables (radar reflectivity Z, rainfall intensity R and specific attenuation k), and total path integrated attenuation (PIA) estimations. The analysis concerns single frequency, incoherent and non-polarimetric radar systems. Two attenuation correction algorithms are studied: a forward scheme algorithm based on the analytical solution proposed by Hitschfeld and Bordan (1954) and a backward scheme algorithm based on the solution proposed by Marzoug and Amayenc (1994). From DSD range profiles, the corresponding profiles of integral radar variables are derived. Using a Monte Carlo approach, the accuracy and robustness of the two algorithms are quantified for the different sources of error previously mentioned.

References:

Berne, A. and R. Uijlenhoet, 2005: A stochastic model of range profiles of raindrop size distributions: Application to radar attenuation correction. Geophys. Res. Lett., 32, L10803, doi:10.1029/2004GL021899.

Hitschfeld, W., and J. Bordan (1954), Errors inherent in the radar measurement of rainfall at attenuating wavelengths, J. Meteorol., 11, 58-67.

Marzoug, M., and P. Amayenc (1994), A class of single- and dual-frequency algorithms for rain-rate profiling from a spaceborne radar. part I: Principle and tests from numerical simulations, J. Atmos. Oceanic Technol., 11(6), 1480-1506.