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The Thermospheric Column O/N2 Ratio
1Department of Physics and Astronomym, George Mason University, Fairfax, VA, USA.
Journal of Geophysical Research. Space Physics
|May 10, 2021
Summary
The O/N2 column density ratio, crucial for interpreting Earth's thermosphere using far ultraviolet (FUV) imaging, has had its meaning clarified. A new, simplified method improves its calculation from emission ratios for better thermospheric research.
Area of Science:
- Space Physics
- Atmospheric Science
- Geophysics
Background:
- The O/N2 column density ratio was introduced over 20 years ago to interpret thermospheric processes using far ultraviolet (FUV) imaging.
- This ratio is vital for understanding the global thermosphere but remains conceptually misunderstood and misapplied.
- It is a key measurement for current and future FUV remote sensing missions studying thermospheric variability.
Purpose of the Study:
- To review the historical context of the O/N2 column density ratio.
- To clarify the physical meaning of this geophysical quantity and resolve existing literature misunderstandings.
- To present a simplified, first-principles approach for deriving the O/N2 column density ratio.
Main Methods:
- Review of the original derivation of the O/N2 column density ratio from OI 135.6 nm and N2 Lyman-Birge-Hopfield (LBH) emissions.
- Analysis of algorithmic synthesis using precomputed models and table lookups.
- Development and application of a simplified methodology based on first principles.
Main Results:
- The study clarifies the conceptual meaning and application of the O/N2 column density ratio.
- A simplified approach to calculate the O/N2 column density ratio from emission ratios is proposed.
- This new method is being successfully applied to satellite data (e.g., Ionospheric CONnection satellite).
Conclusions:
- Clarification of the O/N2 column density ratio enhances its utility in thermospheric research.
- The simplified methodology offers a more generalized and accessible way to derive this key parameter.
- This work supports improved analysis of FUV remote sensing data for understanding thermospheric dynamics.
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