[P-EM10] Space Weather and Space Climate

[PEM10-P15] Comparison of two methods of auroral altitude estimation based on two-point observations

*柳澤 球大朗¹、Daniel Whiter²、片岡 龍峰³、関 華奈子¹、三好 由純⁴、塩川 和夫⁴、Martin Connors⁵、中平 聡志⁶、鳥居 祥ニ⁷ (1.東京大学大学院理学系研究科、2.サウサンプトン大学、3.国立極地研究所、4.名古屋大学宇宙地球環境研究所、5.アサバスカ大学、6.国立研究開発法人宇宙航空研究開発機構、7.早稲田大学理工学術院総合研究所)

High-energy electrons trapped in the radiation belt can sometimes precipitate into the atmosphere, causing relativistic electron precipitation (REP) events. The emission altitude of the REP-related aurora depends on the energy of precipitating electrons or protons, which can contribute to identifying the possible wave mode which caused the REP. We have identified REP events using the CALorimetric Electron Telescope (CALET) experiment on-board the International Space Station (ISS), above identical all-sky cameras at two observation sites about 25 km apart in Athabasca, Canada. The two sites are Athabasca University Geophysical Observatory (AUGO, 54.71N and 113.31W) and Athabasca University Geospace Observatory (AUGSO, 54.60N and 113.64W), and both cameras are equipped with filters to select N₂⁺ emission at 427.8 nm. To estimate the emission altitude, we applied two different methods to analyze coincident auroral images with overlapping fields of view. In the first method, images are mapped onto a horizontal plane by assuming an emission altitude to find the maximum correlations (Kataoka et al., AnnGeo, 2013). In the second method, images are mapped onto the Earth’s magnetic field lines (Whiter et al., Geosci, 2013). Observations have been made since August 30, 2024. We report the latest results of the comparison of the two methods of auroral altitude estimation based on the data obtained from September, 2024 to May, 2025.