On the Effect of Radome Characteristics on Polarimetric Moments and Sun Measurements of a Weather Radar

摘要

This letter illustrates the effects that the regular pattern of the metallic unions of a four-panel radome had on the polarimetric variables [differential reflectivity Z(dr), copolar differential phase phi(dp) offset, and copolar correlation coefficient (rho(hv))] as well as on the sun measurements of a mobile X-band weather radar. In particular, we focus on the analysis of the spatial distribution of the biases and the temporal variability of the sun measurements. We show that the metallic unions result in a nonnegligible sinusoidal-like spatial variability of the estimated biases (on the order of 7 degrees-8 degrees for phi(dp) offset and 0.4-0.5 dB for Z(dr) bias), as well as a drop in rho(hv) in rain and a large temporal variability in the power measured by sun scans. These effects are compared with the measurements collected without a radome and with the measurements collected with a seamless monoblock radome on the same radar system. It is shown that operating without radome, when possible, has a positive impact on the data quality, largely reducing the spatial variability of the biases and increasing the rho(hv) in rain. Similar performances, without the inherent risks, can be obtained as well with a seamless radome. Nevertheless, regardless of the form of operation, we advocate for monitoring the data quality as accurately as possible if quantitative applications are desired.