A Thunderstorm Identification Method Combining the Area of Graupel Distribution Region and Weather Radar Reflectivity

Abstract

Thunderstorm identification from weather radar data remains a fundamental problem in lightning nowcasting. In this study, a novel thunderstorm identification method combining the area of graupel distribution region and weather radar reflectivity is proposed. To optimize identification parameters of the identification method, the radar echoes with 312 thunderstorms in 17 weather processes in Nanjing area, China, from 2014 to 2015 were identified and tested to obtain the optimal identification parameters.The results indicate that the optimal parameter combination is to set the storm region identification reflectivity threshold at 0°C isothermal level to 30 dBZ and set the area of graupel distribution region to 2 km 2 . With such a parameter combination, the optimal identification results with the probability of detection of 91%, false alarm rate of 6.9%, and critical success index of 85.3% could be obtained. Moreover, the proposed thunderstorm identification method can also provide effective means for thunderstorm nowcasting.Plain Language Summary Thunderstorm is a kind of disastrous weather that often brings us great losses. If thunderstorms can be timely detected, we can take appropriate means to deal with them. Weather radar is considered as an efficient tool for detecting thunderstorms. It is an important problem in the application of weather radar to identify thunderstorms from radar echoes. In the present study, a new method for identifying thunderstorms using dual-polarization weather radar is proposed, which combines reflectivity with the integral area of graupel related to thunderstorm electrification to identify thunderstorms. The method is tested by 312 thunderstorms in 17 weather processes in Nanjing area, China, from 2014 to 2015. The test results show that the method has good thunderstorm identification performance.

Meteorological Aspects of Gamma‐Ray Glows in Winter Thunderstorms

“…In all the cases, a strong radar echo of more than 35 dBZ was observed above the site. Such a high reflectivity is suggestive of graupels and/or heavy rainfall (Dixon & Wiener, 1993; Johnson et al., 1998; Yang et al., 2020). While depending on the events, the horizontal diameter of the high‐reflectivity regions is typically a few kilometers.…”

Impact of Assimilating C‐Band Phased‐Array Radar Data With EnKF on the Forecast of Convection Initiation: A Case Study in Beijing, China

“…Yang et al. (2018) used 20 dBZ as the threshold to identify precipitation echoes. Here, we also consider composite Z first exceeding 20 dBZ as the criterion for convection formation (CF).…”

“…Figure 1 shows that the two boundary layer convergence lines in red rectangle kept approaching each other from 06:30 UTC to 06:42 UTC, and then collided and produced a precipitation echo exceeding 20 dBZ at 06:42 UTC. Yang et al (2018) used 20 dBZ as the threshold to identify precipitation echoes. Here, we also consider composite Z first exceeding 20 dBZ as the criterion for convection formation (CF).…”