Multiple-scattering-induced “ghost echoes” in GPM-DPR observations of a tornadic supercell

Evidences of multiple-scattering-induced pulse stretching for the signal of both frequencies of the Dual Precipitation Radar on board the Global Precipitation Measuring mission core satellite are presented based on collocated ground-based NEXRAD S-band observations of a tornadic supercell occurred over Texas on May 27th, 2014. While the ground-based observations highlight the presence of a tilted convective core the satellite observations show reflectivity profiles with similar slopes in the Ka and Ku radar reflectivity profiles, extending down to the surface in correspondence to the so called bounded weak-echo region, i.e. locations where precipitation is totally or almost entirely absent at the ground. A microphysical retrieval based upon the triple frequency (S-Ku-Ka) observations supports the idea that a dense ice core, located between 4 and 14 km, with particle sizes exceeding 2.5 cm and integrated ice contents exceeding 7.5 kg/m2 is the source of the “ghost-echoes” of the signal in the lower layers.