Measurement Report: Aircraft-Ground Observation Study of a Spring Snowstorm Event in the North China Plain: Cloud Microphysical Characteristics and Precipitation Vertical Structure

Abstract. Studies on the characteristics of snowfall cloud systems contribute to understanding the mechanisms of snow formation and development. In this study, based on observations from King Air 350 and ground–based radar, the microphysical characteristics and vertical structure of precipitation during a spring snowstorm with thunderstorm on March 16, 2023 in the North China Plain are investigated. High concentrations of ice crystals (up to 131.1 L^-1) and limited small-scale cloud droplets (less than 10 cm^-3) was observed in the stratiform cloud area. In regions with heavy snowfall and elevated thunderstorm, the liquid water content in the upper cloud layer (∼-18 °C) is significantly higher than in other areas. Precipitations in these regions exhibited a vertical structure of aggregates and vertical ice crystals above, supercooled water in the middle, and graupel below. During the mid-phase of precipitation in Shangqiu, snow particles partially melted within the warm layer (1.8–2.4 km), increasing the equivalent reflectance factor (Z_e) and doppler velocity (V). And then it refreeze in the sub-zero temperature zone and finally completely melt into liquid droplets below 0.7 km. In the early and late stages, snow melting into wet snowflakes below 0.5 km significantly enhanced the Z_e, V and spectrum width (W). During the late stage, updrafts promoted ice crystal growth and accumulation at 1.5–2.3 km, leading to a peak in Z_e and positive value of V. The vertical structure and phase evolution of precipitation revealed here are significant for understanding the microphysical processes during hydrometeors falling, providing insights to improve precipitation type prediction accuracy.