Detection of Electrification with Dual-Polarimetric Radar Signatures

As convective storms develop and become electrified, typically many ice crystals are produced. These ice crystals can become aligned by the electric field and obtain a mean canting angle that is away from the horizontal. Without electrification, ice crystals will align themselves horizontally due to aerodynamic forces, unless the ice crystals are very small (<30 microns with Brownian motion). If these ice crystals are in high enough concentrations, polarimetric radar can detect them with several variables. As such, previous authors have identified canted ice crystals with differential phase (φdp) and Linear Depolarization Ratio (LDR) for example. Here we investigate the use of the co-to-cross correlation coefficient (ρx) to detect canted ice crystals. We also investigate the temporal and spatial changes of the dual polarimetric variables in context of main charge regions and ice microphysics of investigated storms. The analysis is supported with measurements collected by NCAR's (National Center of Atmospheric Research) S-band polarimetric radar (S-Pol), and Colorado State University's (CSU) S-band polarimetric radar, CHILL. The data set and analysis is further augmented with data from CSU's LMA (Lightning Mapping Array).