Intercomparison of techniques to correct for attenuation of C-band weather radar signals

Abstract

Quantitative application of radar measurements at C band requires correction for attenuation. Algorithms to correct for attenuation and differential attenuation are evaluated based on theoretical analysis as well as radar data. The error structure of three different attenuation correction algorithms based on (a) reflectivity, (b) reflectivity and differential reflectivity, and (c) specific differential propagation phase is analyzed. The error structure of two algorithms to correct the differential attenuation based on (a) reflectivity and differential reflectivity, and (b) specific differential propagation phase is presented. Data from the polarimetric C-band Doppler radar POLDIRAD operated by DLR (Germany) are utilized to intercompare the attenuation and differential attenuation correction algorithms. Radar data and theoretical analysis show that the attenuation correction algorithm using reflectivity and differential reflectivity agrees well with the attenuation correction algorithm based on specific differential phase. Similarly, radar data and theoretical analysis indicate that the algorithms to correct for differential attenuation compare well with each other. In addition the fractional standard error of comparison between the algorithms to correct for attenuation and differential attenuation is in good agreement with theoretical results, providing an indirect verification of the accuracies of the algorithms.