Investigating Significant Model-Observation Discrepancies of Protonated Species in the Martian Ionosphere

Files

staf2229.pdf (2.57 MB)

Links to Files

https://academic.oup.com/mnras/article/545/4/staf2229/8381230

Permanent Link

https://doi.org/10.1093/mnras/staf2229
 http://hdl.handle.net/11603/41537

Collections

UMBC Center for Space Sciences and Technology (CSST) / Center for Research and Exploration in Space Sciences & Technology II (CRSST II)
UMBC Faculty Collection

Author/Creator

Author/Creator ORCID

https://orcid.org/0000-0002-2770-4820

Date

2025-12-16

Type of Work

journal articles
Text

Department

Program

Citation of Original Publication

Cheng, Long, Erik Vigren, Jun Cui, Shane Stone, and Mehdi Benna. "Investigating Significant Model-Observation Discrepancies of Protonated Species in the Martian Ionosphere". Monthly Notices of the Royal Astronomical Society 545, no. 4 (2026): staf2229. https://doi.org/10.1093/mnras/staf2229.

Rights

This work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.
Public Domain

Subjects

Abstract

Ions with mass-to-charge ratios from 2 to 150 have been measured in the Martian ionosphere by the Neutral Gas and Ion Mass Spectrometer (NGIMS) onboard the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission. Among these, protonated species at 31, 33, and 41 atomic mass units (amu) are observed at densities significantly higher than those predicted by photochemical models. In this study, we combine photochemical modeling with NGIMS measurements to investigate these discrepancies in the dayside ionosphere of Mars. For 41 amu ions, photochemical models predicts ArH⁺ densities more than one order of magnitude lower than NGIMS measurements. For 31 and 33 amu ions, modeled densities of HNO⁺ and HO₂⁺ are three orders of magnitude lower than observed values. We find that the vertical profiles reveal striking similarities among (a) the 31, 32, and 33 amu channels and (b) the 41, 42, 43, and 44 amu channels, which cannot be fully explained by interlinked chemical pathways and contributions from oxygen isotopes. Instead, we suggest that instrumental effects, specifically mass channel cross-talk from the strong 32 and 44 amu, provide a plausible explanation for the anomalously high densities reported at 31, 33, and 41 amu.