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Study of the Mid‐Latitude Airglow Responses to Geomagnetic Storms Based on Long‐Term Observations in Japan With the TIMED Satellite and Ionosondes.

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Title: Study of the Mid‐Latitude Airglow Responses to Geomagnetic Storms Based on Long‐Term Observations in Japan With the TIMED Satellite and Ionosondes.
Authors: Hotta, Y.1 (AUTHOR) hotta.yuto@isee.nagoya-u.ac.jp, Shiokawa, K.1 (AUTHOR), Otsuka, Y.1 (AUTHOR), Nishioka, M.2 (AUTHOR), Yue, J.3,4 (AUTHOR)
Source: Journal of Geophysical Research. Space Physics. Mar2026, Vol. 131 Issue 3, p1-17. 17p.
Subject Terms: *Magnetic storms, *Oxygen, Ionosondes, Thermosphere, Atmospheric layers, Artificial satellites
Geographic Terms: Japan
Abstract: Variations in nighttime airglow at mid‐latitudes during geomagnetic disturbances reflect the propagation of atmospheric and plasma disturbances from polar heating as well as local chemical processes. However, their detailed mechanisms remain unclear. In this study, we analyzed the responses of six nighttime airglow emissions to geomagnetic storms using data from airglow temperature photometers at three locations in Japan (Rikubetsu (43.5°N, 143.8°E), Shigaraki (34.8°N, 136.1°E), and Sata (31.0°N, 130.7°E)) over a long‐term period from January 2004 to October 2023. The emissions include the OH Meinel band, O2 atmospheric band, O (557.7 nm), Na (589.3 nm) from the mesopause region, and O (630.0 and 777.4 nm) from the thermosphere. The main results show an increase in the intensity of the 557.7‐nm emission 2 days after geomagnetic storms in the mesopause region and an increase in the 630.0‐nm emission 1 day after storms in the thermosphere. Similar responses were observed in the O2 atmospheric band (mesopause region) and the 777.4‐nm emission (thermosphere) to those of 557.7‐nm and 630.0‐nm emissions, respectively. No significant changes were found in the rotational temperatures of OH and O2. The SABER instrument onboard the TIMED satellite observed a post‐storm increase in the atomic oxygen mixing ratio at altitudes of 90–100 km. We suggest that this atomic oxygen increase contributed to the enhanced 557.7‐nm emission in the mesopause region. Ionosondes over Japan observed rise of ionospheric altitudes and enhancements of foF2 1 day after storms. We discuss their possible relation to the observed thermospheric 630.0‐nm emission enhancements. Plain Language Summary: At night, a faint glow called nighttime airglow, invisible to the naked eye, spreads across the sky. This light is produced when atmospheric atoms and molecules energized by solar ultraviolet radiation, emit photons. Nighttime airglow is a phenomenon observed in the mesopause region, specifically at altitudes of 80–100 km (mesopause region), and within the thermosphere, at altitudes ranging from 200 to 400 km. In this study, we used nighttime airglow data observed at three sites in Japan from 2004 to 2023 to investigate how geomagnetic storms (caused by phenomena like solar storms) affect this light. Our findings revealed that one to 2 days after a geomagnetic storm, the intensity of specific airglow emissions increased at particular altitudes (around 90–100 km and in the thermosphere). We believe this phenomenon is related to a temporal increase in the mixing ratio of atmospheric oxygen in the mesopause region and changes in electron density in the thermosphere. These observed variations could provide important clues for understanding the state of the middle and upper atmosphere. Key Points: Superposed epoch analyses of nighttime airglow intensity and rotational temperature responses to geomagnetic storms were conductedAn increase in O (557.7 nm) intensity at two sites was observed 2 days after storms in the mesopause regionAn increase in O (630.0 nm) intensity at two sites was noticed 1 day after storms in the thermosphere [ABSTRACT FROM AUTHOR]
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Abstract:Variations in nighttime airglow at mid‐latitudes during geomagnetic disturbances reflect the propagation of atmospheric and plasma disturbances from polar heating as well as local chemical processes. However, their detailed mechanisms remain unclear. In this study, we analyzed the responses of six nighttime airglow emissions to geomagnetic storms using data from airglow temperature photometers at three locations in Japan (Rikubetsu (43.5°N, 143.8°E), Shigaraki (34.8°N, 136.1°E), and Sata (31.0°N, 130.7°E)) over a long‐term period from January 2004 to October 2023. The emissions include the OH Meinel band, O2 atmospheric band, O (557.7 nm), Na (589.3 nm) from the mesopause region, and O (630.0 and 777.4 nm) from the thermosphere. The main results show an increase in the intensity of the 557.7‐nm emission 2 days after geomagnetic storms in the mesopause region and an increase in the 630.0‐nm emission 1 day after storms in the thermosphere. Similar responses were observed in the O2 atmospheric band (mesopause region) and the 777.4‐nm emission (thermosphere) to those of 557.7‐nm and 630.0‐nm emissions, respectively. No significant changes were found in the rotational temperatures of OH and O2. The SABER instrument onboard the TIMED satellite observed a post‐storm increase in the atomic oxygen mixing ratio at altitudes of 90–100 km. We suggest that this atomic oxygen increase contributed to the enhanced 557.7‐nm emission in the mesopause region. Ionosondes over Japan observed rise of ionospheric altitudes and enhancements of foF2 1 day after storms. We discuss their possible relation to the observed thermospheric 630.0‐nm emission enhancements. Plain Language Summary: At night, a faint glow called nighttime airglow, invisible to the naked eye, spreads across the sky. This light is produced when atmospheric atoms and molecules energized by solar ultraviolet radiation, emit photons. Nighttime airglow is a phenomenon observed in the mesopause region, specifically at altitudes of 80–100 km (mesopause region), and within the thermosphere, at altitudes ranging from 200 to 400 km. In this study, we used nighttime airglow data observed at three sites in Japan from 2004 to 2023 to investigate how geomagnetic storms (caused by phenomena like solar storms) affect this light. Our findings revealed that one to 2 days after a geomagnetic storm, the intensity of specific airglow emissions increased at particular altitudes (around 90–100 km and in the thermosphere). We believe this phenomenon is related to a temporal increase in the mixing ratio of atmospheric oxygen in the mesopause region and changes in electron density in the thermosphere. These observed variations could provide important clues for understanding the state of the middle and upper atmosphere. Key Points: Superposed epoch analyses of nighttime airglow intensity and rotational temperature responses to geomagnetic storms were conductedAn increase in O (557.7 nm) intensity at two sites was observed 2 days after storms in the mesopause regionAn increase in O (630.0 nm) intensity at two sites was noticed 1 day after storms in the thermosphere [ABSTRACT FROM AUTHOR]
ISSN:21699380
DOI:10.1029/2025JA034616