The Anatomy and Physics of ZDR Columns

Polarimetric radar observations of deep convective storms frequently reveal columnar enhancements of differential reflectivity (Z_DR). Such “Z_DR columns” can extend more than 3 km above the environmental 0 °C level and indicate supercooled liquid drops being lofted by the updraft. In this study, we use a sophisticated spectral bin microphysics model (the Hebrew University Cloud Model) to simulate a deep convective storm and its Z_DR columns. In doing so, we clarify the mechanism of initial Z_DR column formation, quantify its internal hydrometeor structure, and document its complete life cycle. In addition, we explore practical applications of Z_DR columns, demonstrating the relationship between Z_DR column height and updraft speed, and how increases in Z_DR column height are correlated to increased precipitation and hail at the surface after 10-15 minutes.