Hisaki space telescope observations of the large oscillations of Martian hydrogen and oxygen upper atmospheres

Abstract

Analyzing extreme ultraviolet spectra of the Martian upper atmosphere obtained from the Hisaki space telescope, we found anti-correlation between hydrogen (HI Ly-β) and oxygen (OI 1356 Å and OI 1304 Å) airglow brightness during one of the major regional dust storms in Mars Year 33 (Masunaga et al., 2022). Ly-β brightness gradually increased by a factor of 2 over the observation period (LS=213°–232°) while oxygen airglow temporarily decreased by a factor of 3 during the dust storm period. We also found that their brightness varied alternately with a periodicity of ~6–8 days. The magnitude of their periodic airglow variations was ~20–50% for the whole disk, and the periodicity was consistent with that of atmospheric waves observed by the Curiosity Rover on the surface of Mars. These results suggest that hydrogen and oxygen abundances in the Martian upper atmosphere are highly controlled by dust- and wave-couplings between the lower and upper atmosphere, possibly altering the efficiency of hydrogen and oxygen escape from Mars. ReferenceMasunaga, K., N. Terada, N. Yoshida, Y. Nakamura, T. Kuroda, K. Yoshioka, Y. Suzuki, H. Nakagawa, T. Kimura, F. Tsuchiya, G. Murakami, A. Yamazaki, T. Usui, and I. Yoshikawa, Alternate oscillations of Martian hydrogen and oxygen upper atmospheres during a major dust storm, Nature Communications, 13, 6609, 2022