A denser and elevated Martian nightside ionosphere during Mars season Ls 180–360°

Qin, Jun; Zou, Hong; Ye, Yuguang; Hao, Yongqiang

doi:10.1016/j.icarus.2022.115255

Cited by 3 publications

(2 citation statements)

References 51 publications

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“…The mean ionospheric electron density ( n e ) profiles at different SZA ranges are shown in Figure 1. Here we choose to present SZA ranges from 80 to 120°, since at regions with SZA < 115°, day‐to‐night plasma transport is the dominant plasma source of the nightside ionosphere, while at higher solar zenith angles, electron precipitation becomes the main source (Cui et al., 2015; Qin, Zou, Ye, et al., 2022; Withers, Fillingim, et al., 2012).…”

Section: Simulation Resultsmentioning

confidence: 99%

Effects of Solar Wind Density and Velocity Variations on the Martian Ionosphere and Plasma transport—A MHD Model Study

Song,

Lu,

Cao

et al. 2023

JGR Space Physics

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Solar wind dynamic pressure, consisting solar wind density nsw and velocity Vsw, is an important external driver that controls Martian plasma environment. In this study, a 3D magnetohydrodynamic model is applied to investigate the separate influences of solar wind density and velocity on the Martian ionosphere. The spatial distributions of ions in the dayside and near nightside ionosphere under different nsw and Vsw are analyzed, as well as the ion transport process. We find that for the same dynamic pressure condition, the ionosphere extends to higher altitudes under higher solar wind density, indicating that a solar wind velocity enhancement event is more efficient at compressing the Martian ionosphere. A higher Vsw will result in a stronger induced magnetic field, shielding the Martian ionosphere, preventing the penetration of solar wind particles. For the same dynamic pressure, increasing nsw (decreasing Vsw) leads to a higher horizontal ion velocity, facilitating day‐to‐night plasma transport. As a result, the ionosphere extends farther into the nightside. Also, the ion outflow flux is larger for high nsw, which may lead to a higher escape rate. Moreover, the strong crustal fields in the southern hemisphere also cause significant effect to the ionosphere, hindering horizontal ion transport. An additional outflow channel is also provided by the crustal field on the southern dayside, causing different responses of flow pattern between local and global scale while the solar wind condition is varied.

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Section: Simulation Resultsmentioning

confidence: 99%

Effects of Solar Wind Density and Velocity Variations on the Martian Ionosphere and Plasma transport—A MHD Model Study

Song,

Lu,

Cao

et al. 2023

JGR Space Physics

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“…Similarly, Yoshida et al (2021) detected sinusoidal seasonal variations in the number densities of and at an altitude of 200 km, with higher densities near perihelion and lower densities near aphelion. Furthermore, Qin et al (2022) ascertained a denser and elevated Martian nightside ionosphere during Mars season L s 180°-360°.…”

Section: Seasonal Variations Of Precipitating Ion Fluxmentioning

confidence: 99%

On the Seasonal Variations of the Ion Precipitation Down to the Upper Atmosphere of Mars

Qiu,

Yu,

Gong

et al. 2024

ApJ

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We investigate the seasonal variations of ion precipitation, utilizing observations from the Mars Atmosphere and Volatile Evolution mission spanning from 2014 January 4 to 2023 February 14. Our analysis reveals that a diminishing pattern characterizes the transition from Mars season L s 0°–180° to Mars season L s 180°–360°, manifesting as a reduction in precipitating ion fluxes. Additionally, we discern a significant influence of the crustal magnetic field on the seasonal variations in precipitating ion fluxes. Intriguingly, within regions where the crustal magnetic field exhibits a strong quasi-horizontal orientation, opposite seasonal trends become evident. The underlying physical mechanism driving these seasonal variations in ion precipitation is probably attributed to the mass loading effect that may decelerate the solar wind and influence the magnetic pileup. A detailed investigation is further demanded in the future.

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Discrete aurora and the nightside ionosphere of Mars: an EMM–MEX conjunction of FUV imaging, ionospheric radar sounding, and suprathermal electron measurements

Harada,

Fujiwara,

Lillis

et al. 2024

Earth Planets Space

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Since 2021, a new surge in discrete aurora detections at Mars has been observed by the Emirates Mars Ultraviolet Spectrometer (EMUS) onboard the Emirates Mars Mission (EMM) Hope Orbiter as EMUS started to regularly obtain synoptic auroral images with a high sensitivity. Here we report on a fortuitous conjunction between EMM and Mars Express (MEX) using far ultraviolet (FUV) imaging of discrete aurora by EMM EMUS, in situ measurements of suprathermal electrons by the MEX Analyzer of Space Plasma and Energetic Atoms Electron Spectrometer (ELS), and topside radar sounding of the nightside ionosphere by the MEX Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS). In this event, EMM EMUS imaged a clear discrete aurora signature around moderately strong crustal magnetic fields on the nightside near the dusk terminator, 11 min before which MEX MARSIS measured a prominent local enhancement of the peak electron density in the nightside ionosphere and MEX ELS observed an in situ enhancement of suprathermal electrons at the corresponding location. A remarkable geographic agreement is found between the enhancements of the aurora, ionosphere, and suprathermal electrons, suggesting that the enhanced ionization and auroral emission are caused concurrently by precipitating suprathermal electrons. Subsequent images indicate that the discrete aurora slightly changed its shape in 15 min and mostly disappeared in a few hours. The MEX MARSIS measurements of the auroral ionosphere display overlapping ionospheric and surface echoes indicative of horizontal gradients of the peak electron density. Analysis of the overlapping echoes implies that the auroral ionosphere and electron precipitation could be highly structured with horizontal spatial scales on the order of several tens of km. MEX MARSIS also observed a non-auroral ionospheric enhancement with a wider spatial extent than the local auroral enhancement, suggesting alternative sources of the enhanced nightside ionosphere such as plasma transport. The comparison between the ionospheric structures measured by MEX MARSIS, suprathermal electron flux measured by MEX ELS, and discrete auroral emission imaged by EMM EMUS underscores the complexity of the auroral and non-auroral nightside ionospheres. This motivates further investigations of their sources, transport, and connections to the magnetotail dynamics of Mars.

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A denser and elevated Martian nightside ionosphere during Mars season Ls 180–360°

Cited by 3 publications

References 51 publications

Effects of Solar Wind Density and Velocity Variations on the Martian Ionosphere and Plasma transport—A MHD Model Study

Effects of Solar Wind Density and Velocity Variations on the Martian Ionosphere and Plasma transport—A MHD Model Study

On the Seasonal Variations of the Ion Precipitation Down to the Upper Atmosphere of Mars

Discrete aurora and the nightside ionosphere of Mars: an EMM–MEX conjunction of FUV imaging, ionospheric radar sounding, and suprathermal electron measurements

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