Direct Comparisons of Polarimetric C-Band and S-Band Radar in Snow

Abstract

The Canadian Weather Radar Network is currently undergoing an upgrade to po- larimetric, S-Band radar systems. Forecasting experiences in Canada with the legacy C-Band radars lends to the idea that the narrow beamwidth of C-Band sys- tems is preferential for nowcasting the typical shallow lake-effect snow event. This idea is tested by comparing moments from King City radar, just north of Toronto, to the neighboring Buffalo, NY WSR-88D. By transforming the radar data from spherical coordinates to the Cartesian coordinate system, the two radars can be compared directly. Objective analysis indicates that the spatial patterns of reflec- tivity are very similiar, with King maintaining the obvious advantage in resolving fine scale features of lake-effect snow bands through a narrow physical beamwidth. Also, it is shown that comparatively, the mean reflectivity values obtained through this method are similiar, but King City maintains a slight advantage over Buffalo in detecting shallow snow-squalls. In regards to differential reflectivity, a case by case comparison is performed to determine any event biases from the King City radar. With biases removed, both radars indicate similiar mean values of differential re- flectivity, which agrees with theoretical expectations. Results also indicate that the bulk hydrometeor type in synoptic snowfalls tend towards pristine crystals, while lake-effect events tend towards aggregated snow.