Testing the drop‐size distribution‐based separation of stratiform and convective rain using radar and disdrometer data from a mid‐latitude coastal region

Abstract

Stratiform and convective rain are associated with different microphysical processes and generally produce drop‐size distributions (DSDs) with different characteristics. Previous studies using data from (a) a tropical coastal location, (b) a mid‐latitude continental location with semi‐arid climate, and (c) a sub‐tropical continental location, found that the two rain types could be separated in the NW–Dm space, where Dm is the mass‐weighted mean diameter and NW is the normalized intercept parameter. In this paper, we investigate the same separation technique using data and observations from a mid‐latitude coastal region. Three‐minute DSDs from disdrometer measurements are used for the NW‐ versus Dm‐based classification and are compared with simultaneous observations from an S‐band polarimetric radar 38 km away from the disdrometer site. Specifically, RHI (range‐height indicator) scans over the disdrometer were used for confirmation. Results show that there was no need to modify the separation criteria from previous studies. Three‐minute DSDs from the same location were used as input to scattering calculations to derive retrieval equations for NW and Dm for the S‐band radar using an improved technique and applied to the RHI scans to identify convective and stratiform rain regions. Two events are shown as illustrative examples.