Classification of Surface Precipitation Types Using Polarimetric Radar and Wet-Bulb Temperature Profile at KMA

The type of precipitation on the surface is an important meteorological factor that affects road traffic and aircraft operations. WRC (Weather Radar Center) has been providing hydrometeor classification index (HCI) using dual polarization radar to notify the type of precipitation. The HCI classifies hydrometeors into 14 types using the modified NCAR (National Center for Atmospheric Research) hydrometeor classification algorithm (HCA) according to the meteorological conditions over the Korean peninsula every 5 minutes based on HSR (Hybrid Surface Rainfall). However, since the distance between the HSR altitude and the ground varies from 500 m to 3 km, the phase of hydrometeor may change depending on the temperature condition when the hydrometeor particle falls. To address these issues, we developed an advanced surface precipitation types classification algorithm using the hydrometeor composite based on the HSR and the wet-bulb temperature profile.

Wet-bulb temperature profile was calculated from the short range numerical prediction model and divided into 4 types according to a structure of inversion layer that determines whether snow and ice crystal melt or not. We calculated the success index from the results of ground-based hydrometeor classification compared with the observed surface precipitation type to evaluate the performance of this algorithm.