14:45 〜 15:00
[MIS06-05] Lightning activities during the quasi-stationary band-shaped precipitation systems
キーワード：極端降水、雷、線状降水帯
Recently heavy rainfall events are increasing in Japan. Especially during the Baiu-Meiyu rainfall season, heavy rainfall associated with quasi-stationary band-shaped precipitation systems frequently has been occurred. Fatalities reached more than 100 due to flash floods and landslides by some events. We deployed 25 lightning and weather observation systems over the Southeast Asia, western north Pacific islands and Japan to monitor the lightning activities over these regions. In this study, lightning activities were focused on the quasi-stationary band-shaped precipitation systems in 2023.
During July 10, 2023, heavy rainfall was observed over northern Kyushu Island in Japan and rainfall amount reached 266 mm within 12 hours. Lightning was very active during the heavy rainfall. Active lightning clouds were formed over the East China Sea, propagated eastward, reached northern Kyusyu Island and then provided heavy rainfall. Active lightning clouds can be traced back to China continent. Lightning activity has a potential of precursor of heavy rainfall.
Another heavy rainfall was observed over Shikoku Island in Japan during August 9 to 10, 2023 and rainfall amount reached 638 mm within 24 hours. On the other hand, lightning activities were very weak during this case. We analyzed the difference of environmental conditions between the two cases. During the heavy rainfall in northern Kyushu case, west-southwesterly low-level wind provided moisture into the convective clouds. The origin of the moisture can be traced back to China continent. Rich amount of aerosol may lead to create more graupel in the clouds for favorable conditions for lightnings. However, heavy rainfall in Shikoku Island case, south-southeasterly low-level wind was dominant which was blown from the open ocean over the Pacific Ocean. Poor amount of aerosol moisture may suppress creating graupel in the clouds for lightning. It is similar to our previous study that we observed less lightning activity in the tropical cyclone generated far from southeast Asian islands.
During July 10, 2023, heavy rainfall was observed over northern Kyushu Island in Japan and rainfall amount reached 266 mm within 12 hours. Lightning was very active during the heavy rainfall. Active lightning clouds were formed over the East China Sea, propagated eastward, reached northern Kyusyu Island and then provided heavy rainfall. Active lightning clouds can be traced back to China continent. Lightning activity has a potential of precursor of heavy rainfall.
Another heavy rainfall was observed over Shikoku Island in Japan during August 9 to 10, 2023 and rainfall amount reached 638 mm within 24 hours. On the other hand, lightning activities were very weak during this case. We analyzed the difference of environmental conditions between the two cases. During the heavy rainfall in northern Kyushu case, west-southwesterly low-level wind provided moisture into the convective clouds. The origin of the moisture can be traced back to China continent. Rich amount of aerosol may lead to create more graupel in the clouds for favorable conditions for lightnings. However, heavy rainfall in Shikoku Island case, south-southeasterly low-level wind was dominant which was blown from the open ocean over the Pacific Ocean. Poor amount of aerosol moisture may suppress creating graupel in the clouds for lightning. It is similar to our previous study that we observed less lightning activity in the tropical cyclone generated far from southeast Asian islands.