Journal article
The Interconnected Relationship Between Hydrogen and Protons During Martian Proton Aurora Activity: A Combined MAVEN Remote Sensing and In Situ Analysis
Journal of geophysical research. Space physics, Vol.130(4), e2024JA032934
04/2025
DOI: 10.1029/2024JA032934
Abstract
We compare observations of hydrogen (H) and protons associated with Martian proton aurora activity, co‐evaluating remote sensing and in situ measurements during these events. Following the currently understood relationship between penetrating protons and H energetic neutral atoms (ENAs) in the formation of proton aurora, we observe an expected correlation between the H Lyman‐alpha (Ly‐α) emission enhancement (used herein as a proxy for H‐ENAs) and penetrating proton flux. However, we also observe a notable spread in the trend between these two data sets. We find that this spread is contemporaneous with one of two major impacting events: high dust activity or extreme solar activity. Proton aurora events exhibiting a relative excess in penetrating proton flux compared to Ly‐α enhancement tend to correspond with periods of high dust activity. Conversely, proton aurora events exhibiting a relative deficit of penetrating proton flux compared to Ly‐α enhancement are qualitatively associated with periods of extreme solar activity. Moreover, we find that the largest proton aurora events occur during concurrent dust storm and solar events, primarily due to the compounding intensified increase in H column density above the bow shock. Finally, we present a simplified empirical estimate for Ly‐α emission enhancement during proton aurora events based on the observed penetrating proton flux and a knowledge of local dust/solar activity at the time; this estimate provides a straightforward method for predicting auroral activity when direct observations are not possible or available. The results of this study advance our understanding of the interconnected relationship between H and protons during Martian proton aurora activity.
Plain Language Summary
Herein we evaluate concurrent observations of hydrogen and protons associated with Martian proton aurora, as observed by multiple instruments onboard the Mars Atmosphere and Volatile EvolutioN spacecraft. Based on known formation mechanisms of proton aurora, we expect to see a correlation between these two observations, which indeed is the case when the data sets are compared. However, we do not always observe a straightforward correlation between these observations. We explore reasons for this unexpected result within this paper. We find that times when we observe a significantly higher proton flux than expected compared to the proton aurora brightness (i.e., measured as “emission enhancement”) tend to correspond with periods of major dust activity on Mars. Alternatively, times when we observe substantially brighter proton aurora than expected compared to the proton flux are typically associated with periods of extreme solar activity. We also present a simplified correlation that can enable future studies to estimate the brightness of a proton aurora event using only the proton flux if direct measurements of hydrogen associated with proton aurora are not possible or available. The results of this study advance our understanding of the interconnected relationship between hydrogen and protons during proton aurora activity at Mars.
Key Points
We identify a correlation between H Lyman‐α emission enhancement & penetrating proton (H+) flux in ∼two Mars years of proton aurora events
Large offsets from expected correlations are associated with observed variability in H+/H ratios & contemporaneous with extreme dust storms or solar activity
A simple empirical estimate of proton aurora brightness based on penetrating H+ flux is presented for different atmospheric/solar conditions
Details
- Title: Subtitle
- The Interconnected Relationship Between Hydrogen and Protons During Martian Proton Aurora Activity: A Combined MAVEN Remote Sensing and In Situ Analysis
- Creators
- Andréa C. G. Hughes - George Mason UniversityMichael S. Chaffin - University of ColoradoEdwin J. Mierkiewicz - Embry‐Riddle Aeronautical UniversityGina A. DiBraccio - Goddard Space Flight CenterJasper Halekas - University of IowaSarah Henderson - Montana State UniversityNicholas Schneider - University of ColoradoJustin Deighan - University of ColoradoSonal Jain - University of ColoradoNorberto Romanelli - University of MarylandChristina O. Lee - University of California, BerkeleyMajd Mayyasi - Boston UniversityAli Rahmati - University of California, BerkeleyDavin Larson - University of California, BerkeleyShannon Curry - University of Colorado
- Resource Type
- Journal article
- Publication Details
- Journal of geophysical research. Space physics, Vol.130(4), e2024JA032934
- DOI
- 10.1029/2024JA032934
- ISSN
- 2169-9380
- eISSN
- 2169-9402
- Publisher
- Wiley
- Number of pages
- 14
- Grant note
- NASA (80GSFC21M0002)
- Language
- English
- Date published
- 04/2025
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984815906102771
Metrics
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