5:15 PM - 7:15 PM
[MTT38-P03] Statistical analysis of the characteristics of the bolt from the blue lightning discharge
Keywords:lightning, bolt from the blue, MP-PAWR
The Bolt from the blue lightning discharge (BFB) is lightning that strikes where it is not raining on the ground. It can be said to be one of the dangerous types of lightning because it strikes where people tend to be less vigilant against lightning. However, the characteristics of BFB are still not well understood in Japan. In this study, we statistically investigated the characteristics of BFB using 3D lightning observation network (Tokyo LMA), Japanese Lightning Detection Network (JLDN), eXtended Radar Information Network (XRAIN), and Multi-parameter phased array weather radar (MP-PAWR) data. The analysis period of this study is 30 hours and 10 minutes of lightning that occurred in the Kanto region in the summers of 2020 and 2022.
This study investigated the following characteristics of BFB.
-How far is the BFB strike point from the rain area?
-Characteristics of the area where BFB occurs and its internal structure of thunderstorm
We defined the area near the ground where the rainfall intensity is 1mm/hr or more as the rain area by using XRAIN data, and extracted negative polarity lightning that struck outside the rain area using JLDN data, and 243 flashes were extracted. We examined 243 flashes using the 3D discharge path information of LMA, and confirmed that 65 flashes were BFBs. The distance between the strike point and the rain area for the BFB 65 flashes was 2.6 km on average, 1.4 km on median, and 11.2 km on maximum. All 65 flashes extracted as BFB started lightning discharge from region of vertically integrated ice (VII). From this, it may be possible to narrow down the warning area by using VII to set the BFB warning area, rather than setting the BFB warning area outward from the boundary of the rain area. As our future work, we plan to examine whether VII is useful for setting the BFB warning area or not.
This study investigated the following characteristics of BFB.
-How far is the BFB strike point from the rain area?
-Characteristics of the area where BFB occurs and its internal structure of thunderstorm
We defined the area near the ground where the rainfall intensity is 1mm/hr or more as the rain area by using XRAIN data, and extracted negative polarity lightning that struck outside the rain area using JLDN data, and 243 flashes were extracted. We examined 243 flashes using the 3D discharge path information of LMA, and confirmed that 65 flashes were BFBs. The distance between the strike point and the rain area for the BFB 65 flashes was 2.6 km on average, 1.4 km on median, and 11.2 km on maximum. All 65 flashes extracted as BFB started lightning discharge from region of vertically integrated ice (VII). From this, it may be possible to narrow down the warning area by using VII to set the BFB warning area, rather than setting the BFB warning area outward from the boundary of the rain area. As our future work, we plan to examine whether VII is useful for setting the BFB warning area or not.