Exploring the Long-Term Relationship Between Thermospheric ∑O/N<sub>2</sub> and Solar EUV Flux

Column O/N<sub>2</sub> ratio (∑O/N<sub>2</sub>), a physical quantity representing thermospheric disturbances, is influenced by solar extreme ultraviolet radiation flux (Q<sub>EUV</sub>) changes. Investigating the correlation between these two factors is essential...

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Bibliographic Details
Main Authors: Hao Li, Cunying Xiao, Kuan Li, Zewei Wang, Xiaoqi Wu, Yang Yu, Luo Xiao
Format: Article
Language:English
Published: MDPI AG 2025-02-01
Series:Remote Sensing
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Online Access:https://www.mdpi.com/2072-4292/17/4/574
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Summary:Column O/N<sub>2</sub> ratio (∑O/N<sub>2</sub>), a physical quantity representing thermospheric disturbances, is influenced by solar extreme ultraviolet radiation flux (Q<sub>EUV</sub>) changes. Investigating the correlation between these two factors is essential for understanding the evolution of the thermosphere. This study examines the correlation and periodic variations of ∑O/N<sub>2</sub> and Q<sub>EUV</sub> across different phases of solar activity, using data from the Global Ultraviolet Imager (GUVI) spanning from 2002 to 2022. A correlation analysis reveals a positive relationship between ∑O/N<sub>2</sub> and Q<sub>EUV</sub>. The function fitting results show that the magnitude of changes in ∑O/N<sub>2</sub> due to Q<sub>EUV</sub> variations is approximately 30% of the mean ∑O/N<sub>2</sub>. A wavelet analysis reveals their coherence in periodic components of 27-day, annual, and 11-year periods. These results are significant for studying the Sun–Earth coupling mechanism and understanding the impact of space weather on the thermosphere.
ISSN:2072-4292