Weather radar antenna pointing accuracy assessment: three method inter-comparison

The accuracy of weather radar antenna alignment is essential to correctly georeference radar measured variables and constitutes a primary factor in the quality control and characterization of radar observations and downstream products. In the present work, three widespread methods for quantifying the antenna pointing offsets in azimuth and elevation are reviewed and compared under actual operative conditions. The first methods performs an dedicated, offline scan of the Sun-disk and is implemented commercially by a number of weather radar manufacturers. The second method uses daily solar signatures identified in online radar data - so does not interrupt normal data acquisition. The third procedure correlates the measured ground clutter field with a field simulated using a radio-propagation model and a high-resolution digital elevation model. All three methods are currently operative for the weather radar network of the Meteorological Service of Catalonia (SMC). Pointing bias estimates gathered in a dedicated campaign from February to March 2014, during which the offline Sun-scanning procedure was run on a daily basis, allow a direct inter-comparison of the methods. This analysis reflects the advantages and limitations in each case. The discrepancies detected in this short term comparison are further investigated and clarified through the analysis of the bias estimates reported by the methods in the course of a one-year period. The results point out to a potential complementary application of two of the methods which will be discussed in the presentation.