Mars Express radio‐occultation data: A novel analysis approach

Grandin, Maxime; Blelly, Pierre‐Louis; Witasse, Olivier; Marchaudon, A.

doi:10.1002/2014ja020698

Cited by 8 publications

(14 citation statements)

References 26 publications

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“…First, radio occultation experiments can be used to derive electron density profiles, that is, electron densities as a function of the altitude, spanning the altitudes both below and above the peak altitude. These were performed using the Mariner 9 spacecraft (Kliore et al, , ; Withers, Weiner, et al, ), Mars Global Surveyor spacecraft (Hinson et al, ), Mars Express spacecraft (Grandin et al, ; Pätzold et al, ), and recently using the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft (Withers et al, ). The main disadvantage of these profiles is that their spatial coverage is restricted by geometric constraints imposed by the orbits of Earth and Mars (Tyler et al, ; Withers et al, ).…”

Section: Introductionmentioning

confidence: 99%

Characterizing Average Electron Densities in the Martian Dayside Upper Ionosphere

et al. 2019

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We use more than 10 years of the Martian topside ionospheric data measured by the Mars Advanced Radar for Subsurface and Ionosphere Sounding radar sounder on board the Mars Express spacecraft to derive an empirical model of electron densities from the peak altitude up to 325 km. Altogether, 16,044 electron density profiles obtained at spacecraft altitudes lower than 425 km and at solar zenith angles lower than 80° are included in the analysis. Each of the measured electron density profiles is accurately characterized by the peak electron density, peak altitude, and three additional parameters describing the profile shape above the peak: (i) steepness at high altitudes, (ii) main layer thickness, and (iii) transition altitude. The dependence of these parameters on relevant controlling factors (solar zenith angle, solar irradiance, crustal magnetic field magnitude, and Sun‐Mars distance) is evaluated, allowing for a formulation of a simple empirical model. Mars Atmosphere and Volatile EvolutioN Extreme Ultraviolet monitor data are used to show that the solar ionizing flux can be accurately approximated by the F10.7 index when taking into account the solar rotation. Electron densities predicted by the resulting empirical model are compared with electron densities locally evaluated based on the Mars Advanced Radar for Subsurface and Ionosphere Sounding measurements, with the Langmuir Probe and Waves electron density measurements on board the Mars Atmosphere and Volatile EvolutioN spacecraft, and with electron densities obtained by radio occultation measurements. Although the electron densities measured by the Langmuir Probe and Waves instrument are systematically somewhat lower than the model electron densities, consistent with former findings, the model performs reasonably well.

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Section: Introductionmentioning

confidence: 99%

Characterizing Average Electron Densities in the Martian Dayside Upper Ionosphere

et al. 2019

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“…The ground network of stations, including the ESA stations in Australia and the Deep Space Network (DSN) in America, Spain, and Australia (Pätzold et al, 2016) measured the downlink radio signals with both closed-and open-loop recording modes (Pätzold et al, 2004(Pätzold et al, , 2009). These data have been widely used by the community in investigations and data evaluations (Grandin et al, 2015;Marissa et al, 2016;Peter et al, 2014;Sánchezcano et al, 2012;Withers et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Optimization of the Mars ionospheric radio occultation retrieval

Wang

Yue

Wei

et al. 2018

Earth and Planetary Physics

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Electron density is a key parameter to characterize Martian ionospheric structure and dynamics. Based on the ephemeris and auxiliary information derived from the Spacecraft, Planet, Instruments, C‐matrix, and Events (SPICE) toolkit, we calculated the bending angle of signal path from the frequency residuals measured by the Mars Express Radio Science Experiment (MaRS) of the Mars Express (MEX) mission under the assumption of a spherically symmetric ionosphere. We stratified the ionosphere into layers and assumed a linear change of bending angle between layers, to derive profiles in radial distance of refractivity with the optimized parameters of upper integral limit of 4890 km and baseline correction boundary of 3690 km. Meanwhile, we also compared the retrieved electron density profiles between the frequency residuals of the single‐frequency and differential Doppler of the dual‐frequency. In total, ~640 electron density profiles of Martian ionosphere between April 2004 and April 2015 were retrieved successfully. There are 24 profiles identified manually that exhibit an additional sporadic layer occurrence below the normal two‐layers. We also found that the peak altitude of this layer increases with the main peak altitude.

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“…The amount of the electron density data from the dayside Martian ionosphere is nowadays considerably large. Entire electron density profiles (i.e., electron densities as a continuous function of the altitude) were obtained using radio occultation experiments from the Mars Global Surveyor (MGS) [Hinson et al, 1999] and Mars Express satellites [Pätzold et al, 2005;Grandin et al, 2014]. Moreover, the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) in the active ionosphere sounder (AIS) mode provides electron density profiles from the spacecraft altitude down to the altitude of the peak electron density in the ionosphere [Gurnett et al, 2005;Morgan et al, 2008;Sánchez-Cano et al, 2012;Morgan et al, 2013].…”

Section: Introductionmentioning

confidence: 99%

Empirical model of the Martian dayside ionosphere: Effects of crustal magnetic fields and solar ionizing flux at higher altitudes

et al. 2016

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We use electron density profiles measured by the Mars Advanced Radar for Subsurface and Ionosphere Sounding instrument on board the Mars Express spacecraft to investigate the effects of possible controlling parameters unconsidered in the empirical model of Němec et al. (2011, hereafter N11). Specifically, we focus on the effects of crustal magnetic fields and F10.7 proxy of the solar ionizing flux at higher altitudes. It is shown that while peak electron densities are nearly unaffected by crustal magnetic fields, electron densities at higher altitudes are significantly increased in areas of stronger magnetic fields. The magnetic field inclination appears to have only a marginal effect. Moreover, while the N11 empirical model accounted for the variable solar ionizing flux at low altitudes, the high‐altitude diffusive region was parameterized only by the solar zenith angle and the altitude. It is shown that this can lead to considerable inaccuracies. A simple correction of the N11 model, which takes into account both the crustal magnetic field magnitude and the effect of F10.7 at higher altitudes, is suggested.

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Mars Express radio‐occultation data: A novel analysis approach

Cited by 8 publications

References 26 publications

Characterizing Average Electron Densities in the Martian Dayside Upper Ionosphere

Characterizing Average Electron Densities in the Martian Dayside Upper Ionosphere

Optimization of the Mars ionospheric radio occultation retrieval

Empirical model of the Martian dayside ionosphere: Effects of crustal magnetic fields and solar ionizing flux at higher altitudes

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