Empirical Models of Ion Density Distribution in the Dayside Martian Ionosphere

Huang, Junrong; Cao, Y.; Cui, Jun; Hao, Yongqiang; Wu, Xiaoshu; Wan, Xiaoxia; Li, Q. ‐L.; Zhong, Jiahao; Wei, Yong

doi:10.1029/2021ja029226

Cited by 4 publications

(1 citation statement)

References 56 publications

(117 reference statements)

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“…Numerous data analysis efforts over the past several decades have revealed that solar EUV and SXR radiation is of great importance to atmospheric temperature (Forbes et al., 2008; Gu et al., 2020; Jain et al., 2015; Thiemann et al., 2015) and escape rate (Cui, Wu, et al., 2019; Lillis et al., 2017; Mayyasi et al., 2018). A notable outcome of this radiation is the production of a substantial ionosphere on the dayside of Mars via photoionization of atmospheric neutrals, as demonstrated clearly by the observed structural variations of both cold electrons (Fox & Yeager, 2009; Mendillo et al., 2006; Morgan et al., 2008; Němec et al., 2011) and ions (Huang et al., 2020, 2022; Thiemann et al., 2018; S. Q. Wu et al., 2022).…”

Section: Motivationmentioning

confidence: 99%

Disentangling Photoelectrons and Penetrating Solar Wind Electrons in the Dayside Martian Upper Atmosphere

Cao,

Cui,

et al. 2023

JGR Planets

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In situ produced photoelectrons and precipitating solar wind electrons are two distinct hot electron populations in the dayside Martian upper atmosphere. While each population has been known for decades, its relative contribution to the measured hot electron flux has not been adequately characterized up to now. In this study, we implement a two‐stream kinetic model to compute the hot electron flux for a open magnetic field configuration. By comparing model results to realistic data acquired by the Mars Atmosphere and Volatile Evolution mission, we show that the electron fluxes predicted by the pure photoelectron model are enormously underestimated, especially in the direction toward Mars, but the measurements can be adequately reproduced once solar wind electron precipitation is taken into account. Such a precipitation plays a crucial role above 180 km, not only for hot electrons at all energies that move toward Mars but also for electrons above 1,000 eV that move away from Mars due to the backscattering of precipitating electrons. In contrast, the hot electron population is predicted to be mostly composed of photoelectrons below 180 km. The significance of precipitating solar wind electrons is also evaluated, revealing an appreciable impact on the structure of the dayside Martian upper atmosphere at high altitudes, where electron impact ionization is enhanced by a factor of 7 and cold electron heating enhanced by a factor of 4.

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Section: Motivationmentioning

confidence: 99%

Disentangling Photoelectrons and Penetrating Solar Wind Electrons in the Dayside Martian Upper Atmosphere

Cao,

Cui,

et al. 2023

JGR Planets

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Photochemical escape of atomic C, N, and O during the 2018 global dust storm on Mars

Huang

Cui

et al. 2022

Monthly Notices of the Royal Astronomical Society

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Dust storm is an important meteorological phenomenon on Mars. By modifying the structure of the Martian atmosphere and ionosphere, it plays an indispensable role in the Martian photochemistry and atmospheric loss. This study is devoted to evaluating the effects of the 2018 global dust storm (GDS) on the photochemical escape of atomic C, N, and O on Mars based on multi-instrument measurements made by the Mars Atmosphere and Volatile EvolutioN spacecraft. The dataset is divided into the non-dusty and dusty stages, for which the hot atom production rates from a variety of channels are calculated. A one-dimensional Monte Carlo model is then constructed to obtain the escape probability profile for each channel. By combining the above results, we derive the photochemical escape rates, both prior to and during the GDS. Our calculations suggest that the GDS-induced C, N, and O escape is generally reduced by ∼30–$40\%$ relative to the quiet, pre-GDS state, in direct contrast to the well-known result of GDS-induced strong enhancement of atomic H escape. We further propose that the GDS-induced variation of photochemical escape essentially reflects the competition between two effects: the modification of hot atom production (enhancement for photodissociation or reduction for dissociative recombination) driven by the variation of the background atmosphere and the reduction of escape probability due to atmospheric expansion. During the GDS, the latter is usually more effective and responsible for the overall reduction of photochemical escape on Mars.

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Solar wind interaction with Mars: electric field morphology and source terms

Wang

Fatemi

Nilsson

et al. 2023

Monthly Notices of the Royal Astronomical Society

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The correlation between space environment conditions and the properties of escaping ions is a central topic of Mars research. Although empirical correlations have been visible in the data, a physics-based interpretation, rather than statistics-based pictures, has not been established yet. As a first effort, we investigate the electric field, the direct contributor to ion acceleration, in the Mars plasma environment from a hybrid plasma model (particle ions and fluid electrons). We use Amitis, a hybrid model combined with an observation-based ionospheric model, to simulate the Mars-solar wind interaction under nominal solar wind plasma conditions for perpendicular and Parker spiral directions of the interplanetary magnetic field (IMF). The simulations show 1) The electric field morphology is structured by the IMF direction and the different plasma domains in the solar wind-Mars interaction. 2) Asymmetry of the electric field between the hemispheres where the convective electric field points inward and outward, respectively, due to the mass loading and asymmetric draping of the magnetic field lines. 3) The motional electric field dominates in most regions, especially in the dayside magnetosheath. 4) The Hall term is an order of magnitude weaker and significant in the magnetotail and plasma boundaries for a perpendicular IMF case. The Hall term is relatively stronger for the Parker spiral case. 5) The ambipolar electric field, in principle, agrees with MAVEN measurements in the magnetosheath.

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Empirical Models of Ion Density Distribution in the Dayside Martian Ionosphere

Cited by 4 publications

References 56 publications

Disentangling Photoelectrons and Penetrating Solar Wind Electrons in the Dayside Martian Upper Atmosphere

Disentangling Photoelectrons and Penetrating Solar Wind Electrons in the Dayside Martian Upper Atmosphere

Photochemical escape of atomic C, N, and O during the 2018 global dust storm on Mars

Solar wind interaction with Mars: electric field morphology and source terms

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