HR: 0800h
AN: AE31B-0162    [Abstracts]
TI: Blue jet and grafted sprites observed in summertime, Japan
AU: Kanamori, T
EM: sonotaco@yahoo.co.jp
AF: SonotaCo Network, 3-20-4, Daita, Setagaya, 155 Japan
AU: * Takahashi, Y
EM: yukihiro@pat.geophys.tohoku.ac.jp
AF: Department of Geophysics, Tohoku University, Aramaki, Aoba-ku, Sendai, 980-8578 Japan
AU: Adachi, T
AF: Department of Geophysics, Tohoku University, Aramaki, Aoba-ku, Sendai, 980-8578 Japan
AU: Ohkubo, A
AF: Department of Geophysics, Tohoku University, Aramaki, Aoba-ku, Sendai, 980-8578 Japan
AU: Yamamoto, K
AF: Department of Geophysics, Tohoku University, Aramaki, Aoba-ku, Sendai, 980-8578 Japan
AU: Sato, M
AF: Riken, 2-1 Hirosawa, Wako, 351-0198 Japan
AU: Cummer, S A
AF: Electrical and Computer Engineering Department, Duke University, Hudson Hall 130, Durham, NC 27708 United States
AB: Jet-like phenomena associated with cloud-to-ground or intracloud lightning discharges were detected by normal video frame rate CCD cameras installed at two observation sites in Tokyo using a real time data processing software, named UFO Capture, on July 8, 2004. A blue starter event was found 0.2 after cloud flash. The blue jet event started 0.35 sec after the same cloud flash and extended upward, lasting for 0.38 sec with few re-enhancements in brightness. On a field image taken when the luminosity of jet peaked in time, two sprite clusters appeared at the top of the jet, like as a grafted tree. The estimated bottom and top heights of blue jet are 17 km and 46 km, respectively, while the top altitude of sprites is 80 km. These characteristics are consistent with parameters of blue jet, blue starter and sprites, reported in previous studies but the combination of the jet and grafted sprite feature would be the first case. We examined the polarity and charge moment of the lightning or possibly jet/sprites discharge using VLF and ELF waveforms recorded within a few hundred km from the events. The results suggest that both the grafted sprites and blue jet play some role to charge up the lower ionosphere, rather than to reduce the electric potential like as normal sprites caused by positive cloud to ground discharge.
DE: 2409 Current systems (2708)
DE: 2411 Electric fields (2712)
DE: 2427 Ionosphere/atmosphere interactions (0335)
DE: 0341 Middle atmosphere--constituent transport and chemistry (3334)
SC: Atmospheric and Space Electricity [AE]
MN: 2004 AGU Fall Meeting