Using Polarimetric Radar Observations to Characterize First Echoes of Thunderstorms and Nonthunderstorms: A Comparative Study

Abstract

This work compares the characteristics of the first echoes of thunderstorms and nonthunderstorms retrieved from S‐band polarimetric radar observations. Observations of 57 (39) isolated thunderstorm (nonthunderstorm) cells with roughly equivalent aerosol and water vapor conditions but different convective available potential energy were obtained with a S‐band polarimetric radar and three independent lightning location systems during 2016/2017 in southern China. Storms with the first echoes were divided into three types based on echo top heights, namely, type 1 (below 0°C layer), type 2 (0°C to −10°C), and type 3 (above −10°C layer). Our observations show median values of radar reflectivity (ZH) and differential reflectivity (ZDR) of type 1 and type 2 in warm phase layer (below 0°C layer) are obviously greater in nonthunderstorms than in thunderstorms, but this feature is not significant in type 3 storms. In the mixed 1 phase layer (0°C to −10°C), median ZH in type 2 is greater in nonthunderstorms while median ZDR in type 3 is slightly smaller. In the mixed 2 phase layer (−10°C to −38°C), median ZH is greater in thunderstorms while median ZDR is smaller, and ZDR values in nonthunderstorms are closer to zero. Although results of ZDR comparisons in the mixed phase are likely affected by random errors and/or residual bias errors, these different signatures suggest different characteristics of liquid or ice particles between thunderstorms and nonthunderstorms. This study is expected to advance our understanding of physical processes responsible for the generation of the first flash.

Understanding the Effects of Aerosols on Electrification and Lightning Polarity in an Idealized Supercell Thunderstorm via Model Emulation

“…To investigate whether increasing the CCN concentration changes convection, Figure 2 shows the spatial distribution of radar reflectivity during different stages of the storm for different aerosol scenarios. Based on the characteristics of reflectivity and lightning activity (van den Broeke et al., 2008; Liu et al., 2021; Lu et al., 2022; C. Zhao et al., 2022), the different stages of storm development, that is, initial (Figures 2a, 2d, and 2g), developing (Figures 2b, 2e, and 2h), and pre‐mature (Figures 2c, 2f, and 2i), were identified. Convection developed later in the polluted run than in the Ctrl and clean cases.…”