Analysis of the self-consistency property in an Argentine polarimetric weather radar

Abstract

Accurate calibration of polarimetric weather radars is essential for quantitative precipitation estimation and hydrometeor classification. This work applies a method for the absolute calibration of horizontal reflectivity, ZH , based on theself-consistency principle of polarimetric variables in rain. Data from an operational C-band polarimetric radar in Argentina are used. The specific differential phase, KDP , is estimated from the propagation differential phase profile, ΦDP , using two approaches: linear regression fitting and moving average filtering followed by finite differencing. Simultaneously, KDP is estimated from measurements of horizontal reflectivity, ZH , and differential reflectivity, ZDR , using an empirical relationship derived from a precipitation rate model. An expression for the radar calibration constant, C, is derived from the analytical models of KDP . Initial results show differences between the twoapproaches to estimating KDP , and considerable scatter when compared with the KDP derived from ZH and ZDR , which is attributed to the low precipitation intensity in the analyzed event. Despite the variability, the method demonstrates potential for operational calibration without the need for external references. The implications of these results and directions for future work are discussed, including applying the method to more intense precipitation events to improve the robustness of the calibration constant estimation.