Long-term radar observations of the melting layer of precipitation and their interpretation

Abstract

In this study, 600 h of vertically pointing X-band radar data and 50 h of UHF boundary layer wind profiler data were processed and analyzed to characterize quantitatively the structure and the causes of the radar signature from melting precipitation. Five classes of vertical profiles of reflectivity in rain were identified, with three of them having precipitation undergoing a transition between the solid and liquid phase. Only one of them, albiet the most common, showed a radar brightband signature. The classical brightband explanation accounts for less than half of the observed reflectivity enhancement; the difference could be explained by effects associated with the shape and density of melting snowflakes and, to a smaller extent, by precipitation growth in the melting layer and aggregation in the early stages of the melting followed by breakup in the final stages. -from Authors