Radar-based Hail Detection: Impact of Height Assignment Errors on the Measured Vertical Profiles of Reflectivity

Most hail detection algorithms for single-polarization radars are based on the analysis of the vertical profiles of reflectivity. These profiles are estimated from the volumic data generated by a scanning at multiple elevations. Beside the usual sources of errors affecting the radar reflectivity, the estimated vertical profiles are also affected by the uncertainties in the trajectories of the radar beams. This results in uncertainties in the height assignment of the measured reflectivities, and thus introduces errors in the measured vertical profiles.

To get a first idea of the effect of these errors on the estimated probability of hail (POH), RMI (Belgium) and KNMI (The Netherlands) have started a study in which the volumic data from the radars of Wideumont and De Bilt are compared, as well as the derived probability of hail.