[P-EM07_30PM1] Lightning and TLEs and their effects on the lower and middle atmosphere

★ [PEM07-02] 宇宙からの多波長光学観測による雷放電特性の推定

*足立 透¹、佐藤 光輝²、牛尾 知雄³、山崎 敦⁴、鈴木 睦⁴、菊池 雅行⁵、高橋 幸弘²、Inan Umran⁶、Linscott Ivan⁶、芳原 容英⁷、Cohen Morris⁶、Lu Gaopeng⁸、Cummer Steven⁸、Hsu Rue-Ron⁹、Chen Alfred⁹、Frey Harald¹⁰ (1.早稲田大学高等研究所、2.北海道大学理学研究院、3.大阪大学工学研究科、4.宇宙航空研究開発機構宇宙科学研究所、5.国立極地研究所、6.スタンフォード大学電気工学科、7.デューク大学電気コンピュータ工学科、8.国立成功大学物理学科、9.カリフォルニア大学バークレー校宇宙科学研究所、10.電気通信大学情報理工学部)

キーワード：lightning, CG, IC, satellite, remote sensing

The present study analyzes satellite optical data to evaluate the effectiveness of spaceborne spectrophotometric measurement in characterizing properties of lightning flash. The main data analyzed here are those obtained by FORMOSAT-2/ISUAL limb observation and ISS/GLIMS nadir observation. While ISUAL spectrophotometer observes optical emissions of 150-280, 316, 337, 392, 762, 600-900 nm at a sampling rate of 10 kHz, GLIMS observes emissions of 150-280, 337, 762, 600-900, 316, 392 nm at a rate of 20 kHz. These data for the first time derive fine spectral and temporal properties of lightning emission observed from space. By analyzing the ISUAL optical data and ground-based radio data, we found that spectral intensity ratio is a new parameter to discriminate intra-cloud (IC) and cloud-to-ground (CG) lightning discharges: the blue/red intensity ratio of CG strokes tends to be lower than that of IC pulses. We also found similar tendency in GLIMS lightning events. A case study showed that the color of lightning turned to red when a very bright impulsive emission, which is consistent with a ground return stroke, occurred. These results consistently suggest that the color of CG component is redder than that of IC component, and we explain this as a result of the Rayleigh scattering which effectively attenuates blue light emissions in the case of light sources located at lower-altitudes such as CGs. Using this technique, we will further examine the lightning characteristics on a global level, focusing on latitudinal dependences and land/ocean contrast for example.