[M-IS13] Atmospheric electricity: Application of technology for reducing disaster risks

[MIS13-03] Analyses about the magnitude of the charge neutralization by numerical simulations targeting on the lightning events over the Kanto area during summer of 2023.

*Yousuke Sato¹, Mitsuteru Sato¹, Masaru Inatsu¹, Atsushi Nagao², Yumiko Yamashita², Masuda Toshihisa², Naomichi Nakamura², Ikeda Takashi², Makoto Hosoda³, Farhan Mahmood³ (1.Faculty of Science, 2.NTT Space Environment and Energy Laboratories, 3.Technical Assistance and Support Center, Service Operation Department, NTT EAST Corporation)

Keywords:Bulk Lightning Model, Charge nautralization, Lightning

In this study, we investigated the seasonal variability of the charge neutralization in lightning events over the Kanto region during summer of 2023 using a bulk lightning model coupled with a meteorological model Scalable Computing for Advanced Library and Environment (SCALE). The numerical simulations were conducted to examine the differences in the seasonal variability of the magnitude of the charge neutralization estimated from the ground base measurement conducted by our group during the period (Sato et al. 2024). Our simulation successfully reproduced the measured difference between the magnitude of the charge neutralization in early summer i.e., from late June to the early July and that in the late summer, i.e., from late July to August. Based on the analyses for the results of the simulation, we elucidated the difference of the magnitude of the charge neutralization as following. In the early summer, the charge separation frequently occurs and results in the large charge density because the large amount of graupel, which is critical to the charge separation in the cloud, is generated under the unstable and moist condition. In such condition, the magnitude of the charge neutralization tends to be large. In contrast, the graupel amount and the charge separation were both small due to the relatively stable condition during the late summer, and as consequence, the magnitude of the charge neutralization is small in late summer.