Analysis and practice for observing artificially triggered lightning with a ground-based microwave radiometer

The paper presents a systematic description about the observation scheme analysis and practical observation of artificially triggered lightning with a ground-based microwave radiometer together with other discharging observation instruments at Guangzhou Field Experiment Site for Lightning research and testing in Conghua, Guangdong in the thunderstorm season of the 4 consecutive years from 2016 to 2019. The results from statistical analysis of the brightness temperature data observed from 2017 to 2019 show that: (1) The frequencies such as 28, 30, 51.25 and 51.76 GHz in atmospheric window are more likely to respond with outstanding brightness temperature pulses than other observation frequencies of the radiometer; (2) When the elevation angle is 30 degrees , the observation distance is relatively short (99 m in this study), and the "lightning observation mode" is adopted, the efficiency for a ground-based microwave radiometer to capture the lightning heating effect caused by artificially triggered lightning can be improved; (3) The observation efficiency of the 3 years as a whole is 71.4% but gradually increases year by year; (4) The radiometer observation data can be used to reveal the characteristics of lightning heating effects such as duration and lightning current integral; (5) Combined with the lightning current data measured by a coaxial shunt during the experiment, it was found that the estimated lightning heating effect durations based on 25 artificially triggered lightning observations are well consistent with the lightning current durations, as shown by the correlation coefficient of 0.73. This also implies that the radiometer working on the lightning observation mode presented by this paper can observe the lightning heating effect and estimate its duration.