Drop-size distributions of raindrops by polarization radar and simultaneous measurements with disdrometer, windprofiler and PMS probes

Multiparameter polarimetric weather radars offer the possibility of estimating raindrop size distribution directly. The retrieved parameters of exponential drop-size distributions are compared with discrete drop-size spectra obtained from a vertical-pointing radar (windprofiler type), airborne particle measuring systems (PMS) probes and a disdrometer. The windprofiler and PMS probes allow simultaneous measurements at almost the same location. This unique data set shows that radar-estimated drop-size distributions can be retrieved with the same quality as distributions from other standard instruments. Results obtained with a C-band radar during the CLEOPATRA (Cloud Experiment Oberpfaffenhofen and Transports) campaign in southern Germany are confirmed by measurements with an S-band radar in southern England. The quality of the estimated rain rate is high, but differences in quantity can be caused not only by differences in the instrumental set-up but also by deviation from an exponential shape of the drop-size distribution.