96 / 2023-08-25 10:25:31

Study on the first lightning warning method of isolated thunderstorm cells in South China

the first lightning; radar; thunderstorm

雷电预警预报技术及其应用 > 雷电预警预报技术

This study improves the first lightning warning method of isolated thunderstorm cells based on observations during 2016/2017 in Southern China using S-band polarimetric radar and three independent lightning location systems. Conclusions are as follows: ( 1 ) The median value of horizontal reflectivity ( Z_H ) ≤15 dBZ below the melting layer is a good indicator for warning the first lightning when cloud is first detected by radar with the maximum value of composite reflectivity ≥ 5 dBZ. In analysis/test samples, the probability of detection ( POD ) is ~0.96/1, false alarm ratio ( FAR ) is ~0.32/0.38, critical skill index ( CSI ) is ~0.66/0.63, and the average leading time is ~21/12 min; ( 2 ) Methods of minimum echo ( 20 dBZ ) top height extends to −10°C and the 35 dBZ at −10°C are also well for identifying lightning occurrence. The POD is ~1/1, FAR is ~ 0.08/0.29, CSI is ~0.92/0.71 and the average leading time is ~8/5 min of the former algorithm in analysis/test samples. For the latter algorithm, the POD is ~1/1, FAR is ~ 0.06/0, CSI is ~0.94/1 and the average leading time is ~5/3 min in analysis/test samples. However, the differential reflectivity ( Z_DR ) column and the height of graupel are not as effective as the reflectivity information on warning the first lightning of thunderstorms in this study.