Electrified Cloud Areas Observed in the SHV and LDR Radar Modes

Strong in-cloud electric fields align ice particles that can be observed with polarization diversity radars. Radar data collected in the simultaneous transmission mode, wherein horizontally and vertically polarized waves are simultaneously transmitted and received (SHV), and in a mode whereby a single-polarization wave is transmitted and dual (orthogonal)-polarization waves are received simultaneously [linear depolarization (LDR) mode] are analyzed. The necessary time delay between the SHV and LDR modes for our radar was about 1–4 min. The data show that the areas of canted crystals from the LDR mode are larger than those from the SHV mode, thereby indicating that the LDR mode is more sensitive to canted ice cloud particles than the SHV mode. The data also demonstrate that the differential phase and correlation coefficient in the LDR mode are indicative of canted cloud crystals and that these variables often are more sensitive to canted crystals than the linear depolarization ratio studied earlier. Rapidly scanning radars such as those with a phased array antenna could operate sequentially in the SHV and LDR modes and thus better detect cloud volumes characterized by enhanced electric fields.