Altitude of pulsating arcs as inferred from tomographic measurements

• Published in: Earth, Planets and Space
• Main Authors: Vladimir Safargaleev, Tima Sergienko, Keisuke Hosokawa, Shin-ichiro Oyama, Yasunobu Ogawa, Yoshizumi Miyoshi, Satoshi Kurita, Ryochi Fujii
• Format: Article in Journal/Newspaper
• Language: English
• Published: SpringerOpen 2022
• Subjects: Pulsating auroras; Internal modulation; Altitude of auroras; Optical tomography; Geography. Anthropology. Recreation; G; Geodesy; QB275-343; Geology; QE1-996.5; Kiruna; Tjautjas
• Online Access: https://doi.org/10.1186/s40623-022-01592-8; https://doaj.org/article/5a01860ee85e42b0ac96394a317600b4

Abstract Data from three all-sky cameras in Kiruna and Tjautjas (Sweden) were used to estimate the altitude of pulsating arc-like forms using optical tomography. The event under consideration occurred during the substorm recovery phase and comprised both periodic luminosity variation of the on/off type with repetition periods of 3–6 s (main pulsations) and faster scintillation (approximately 2 Hz) during the “on” phase of the main pulsations. It is found that (1) the altitudes of the pulsating auroral arcs decrease during “on” intervals from ~ 95 km to ~ 92 km and (2) for two closely spaced arcs, internal modulation took place only in the lowest arc. The results may be interpreted in the frame of the traditional mechanism assuming electron scattering via VLF-wave/particle interaction in the equatorial magnetosphere, while the internal modulation may also be alternatively interpreted in the frame of the less-often inferred mechanism of field-aligned acceleration somewhere between the equatorial plane and ionosphere. Graphical Abstract