AE33C-0510
The Associated Sferics of the ISUAL Blue Luminous Events
Wednesday, 16 December 2015
Poster Hall (Moscone South)
Jung-Kuang Chou1, Rue-Ron Hsu2, Han-Tzong Su3, Alfred Bing-Chih Chen3, Cheng-Ling Kuo4, Sung-Ming Huang1, Shu-Chun Chang3, Yen-Jung Wu3, Peng Kang-Ming3, Harald U Frey5, Yukihiro Takahashi6 and Lou-Chuang Lee7, (1)National Cheng Kung University, Tainan, Taiwan, (2)NCKU National Cheng Kung University, Physics, Tainan, Taiwan, (3)NCKU National Cheng Kung University, Tainan, Taiwan, (4)Institute of Space Science National Central University, Jhongli, Taiwan, (5)University of California Berkeley, Berkeley, CA, United States, (6)Hokkaido University, Sapporo, Japan, (7)Institute of Earth Sciences Academia Sinica, Taipei, Taiwan
Abstract:
ISUAL has recorded many mystic blue luminous events (BLEs) that emit clear middle ultraviolet to blue emissions (230−450 nm) but contain dim red emissions (653−754 nm). Most BLEs appear to be dot-like on the ISUAL images, and a few BLEs develop further into blue jets or type II gigantic jets (GJs). The associated sferics of the BLEs in the extremely low frequency to the very low frequency (ELF/VLF) band and the low frequency (LF) band exhibit similar features to those of the VLF/LF waveform for the narrow bipolar events (NBEs). The ISUAL BLE is conjectured to be the accompanied light emissions from the NBE-like event. Both positive and negative discharge polarity-types for the BLEs have been found. Based on the sferics and the ISUAL optical data, a NBE-like event is found to be related to a rapidly-flowing current of the initiation discharge in the thunderstorm, while a blue jet or a type II GJ is suggested to be associated with the slowly-varying current of the ensuing discharge. The selected six blue jets and one type II GJ occurring within 3,500 km from the NCKU sferics-detecting stations are inferred to be positive upward discharges. The spectral characteristics of BLEs resemble those of the emissions mostly from the non-thermal air plasmas produced by the locally-enhanced electric field, rather than those from the hot air plasmas in local thermodynamic equilibrium (LTE).
