Differential Reflectivity Bias and Antenna Temperature

Differential reflectivity (Zdr) calibration for weather radars is an ongoing area of research. A accurate estimation of the Zdr bias is importat for both quantitative and qualitative interpretation of Zdr. It has recentely been shown that the Zdr bias is a function of the ambient tempaerature at the radar site (Hubbert, 2017, JTECH), however, the the specific cause of the temperature dependednt bias is not well understood. Numerical modeling of the NCAR's S-Pol (S-band Dual Polarimetric Radar) is carried out in an attemt to indentify the source of the Zdr bias. Modeling results and experimental data are presented to illustrate the concepts.