scholarly journals Mars Global Surveyor radio science electron density profiles : Neutral atmosphere implications

2001 ◽  
Vol 28 (16) ◽  
pp. 3091-3094 ◽  
Author(s):  
Stephen W. Bougher ◽  
Steffi Engel ◽  
David P. Hinson ◽  
Jeffrey M. Forbes
Keyword(s):  
Electron Density ◽  
Neutral Atmosphere ◽  
Mars Global Surveyor ◽  
Density Profiles ◽  
Radio Science ◽  
Electron Density Profiles

scholarly journals Solar wind modulation of the Martian ionosphere observed by Mars Global Surveyor

2004 ◽  
Vol 22 (6) ◽  
pp. 2277-2281 ◽  
Author(s):  
J.-S. Wang ◽  
E. Nielsen
Keyword(s):  
Solar Wind ◽  
Electron Density ◽  
Neutral Atmosphere ◽  
Mars Global Surveyor ◽  
Ionospheric Electron Density ◽  
Density Profiles ◽  
Energetic Proton ◽  
Martian Ionosphere ◽  
Proton Precipitation ◽  
Electron Density Profiles

Abstract. Electron density profiles in the Martian ionosphere observed by the radio occultation experiment on board Mars Global Surveyor have been analyzed to determine if the densities are influenced by the solar wind. Evidence is presented that the altitude of the maximum ionospheric electron density shows a positive correlation to the energetic proton flux in the solar wind. The solar wind modulation of the Martian ionosphere can be attributed to heating of the neutral atmosphere by the solar wind energetic proton precipitation. The modulation is observed to be most prominent at high solar zenith angles. It is argued that this is consistent with the proposed modulation mechanism.

A Sporadic Third Layer in the Ionosphere of Mars

Science ◽  
2005 ◽  
Vol 310 (5749) ◽  
pp. 837-839 ◽  
Author(s):  
M. Pätzold ◽  
S. Tellmann ◽  
B. Häusler ◽  
D. Hinson ◽  
R. Schaa ◽  
...  
Keyword(s):  
Electron Density ◽  
Charge Exchange ◽  
Layer Structure ◽  
Electron Densities ◽  
Ionospheric Layer ◽  
Density Profiles ◽  
Mars Express ◽  
Radio Science ◽  
Martian Ionosphere ◽  
Electron Density Profiles

The daytime martian ionosphere has been observed as a two-layer structure with electron densities that peak at altitudes between about 110 and 130 kilometers. The Mars Express Orbiter Radio Science Experiment on the European Mars Express spacecraft observed, in 10 out of 120 electron density profiles, a third ionospheric layer at altitude ranges of 65 to 110 kilometers, where electron densities, on average, peaked at 0.8 × 1010 per cubic meter. Such a layer has been predicted to be permanent and continuous. Its origin has been attributed to ablation of meteors and charge exchange of magnesium and iron. Our observations imply that this layer is present sporadically and locally.

Mutual radio occultation experiment between ExoMars Trace Gas Orbiter and Mars Express: algorithms testing

2021 ◽  
Author(s):  
Bruno Nava ◽  
Yenca Migoya-Orue ◽  
Anton Kashcheyev ◽  
Beatriz Sánchez-Cano ◽  
Olivier Witasse ◽  
...  
Keyword(s):  
Experimental Data ◽  
Electron Density ◽  
Doppler Shift ◽  
Radio Occultation ◽  
Trace Gas ◽  
Neutral Atmosphere ◽  
Ionospheric Electron Density ◽  
Density Profiles ◽  
Mars Express ◽  
Electron Density Profiles

<p>Radio Occultation (RO) is a very powerful technique to probe a planetary atmosphere, in providing vertical density profiles of the neutral atmosphere and ionosphere. The standard method uses a radio link between a spacecraft and an Earth ground station. Nevertheless, the possibility to obtain information about the Martian atmosphere with mutual RO events, using data from NASA Mars Odyssey and Mars Reconnaissance Orbiters (MRO), has been demonstrated by Ao et al. (2015).<br />Taking advantage of two European spacecraft in orbit around Mars, the European Space Agency is currently preparing experiments of mutual RO between Mars Express (MEX) and the ExoMars Trace Gas Orbiter (TGO). In preparation of MEX and TGO data inversion and analysis, a simulation-based strategy has been adopted and an algorithm able to retrieve vertical electron density profiles from Doppler shift measurements has been implemented and validated. Subsequently, in order to test the mentioned algorithm with experimental data, the same three RO events considered in the paper by Ao et al. (2015) have been processed. In particular, for each RO event, having the information about the satellites’ orbit, the (excess) Doppler shift values corresponding to the Mars Odyssey-MRO ray-paths have been converted to bending angles as a function of impact parameter. Then, assuming a spherical symmetry (Fjeldbo et al., 1971) for the ionosphere electron density, the bending angles have been transformed (through Abel integral) to a vertical refractivity profile, which, in turn, has been converted to an ionospheric electron density profile.<br />In this work, the results obtained by the application of the mentioned inversion algorithm to experimental data will be presented, with particular focus on the retrieval of the ionospheric electron density profiles.</p> <p><strong>References</strong></p> <p>Ao, C. O., C. D. Edwards Jr., D. S. Kahan, X. Pi, S. W. Asmar, and A. J. Mannucci (2015), A first demonstration of Mars crosslink occultation measurements, Radio Sci., 50, 997–1007, doi:10.1002/2015RS005750.</p> <p>Fjeldbo, G., A. J. Kliore, and V. R. Eshleman (1971), The neutral atmosphere of Venus as studied with the Mariner V radio occultation<br />experiments, Astron. J., 76, 123–140.</p>

scholarly journals Assessment of electron density profiles over the Brazilian region using radio occultation data aided by global ionospheric maps

2020 ◽  
Author(s):  
Gabriel Jerez ◽  
Fabricio Prol ◽  
Daniele Alves ◽  
João Monico ◽  
Manuel Hernández-Pajares
Keyword(s):  
Refractive Index ◽  
Electron Density ◽  
Radio Occultation ◽  
Electron Content ◽  
Neutral Atmosphere ◽  
Density Profiles ◽  
Total Electron ◽  
Ionospheric Variability ◽  
Electron Density Profiles ◽  
Global Ionospheric Maps

<p>The development of GNSS (Global Navigation Satellite System) and LEO (Low Earth Orbiting) satellites missions enhanced new possibilities of the terrestrial atmosphere probing. The Radio Occultation (RO) technique can be used to retrieve profiles from the neutral and the ionized atmosphere. An important advantage of using RO data is the spatial distribution, which enables global coverage. The signal transmitted by GNSS satellites and tracked by receivers embedded at the LEO satellites is influenced by the atmosphere which causes signal refraction. Due to the signal and atmospheric interaction, instead of a straight line, the signal propagates as a curved line in the path between the transmitter and receiver. The satellites geometry allows the retrieval of atmospheric refractive index, which carries several characteristics from its composition, such as pressure and temperature of the neutral atmosphere, and electron density of the ionosphere. In 1995 GPS/MET (Global Positioning System/Meteorology) experiment was launched to prove the RO concept and, since then, several LEO missions with GNSS receiver embedded were developed, such as CHAMP (Challenging Mini-satellite Payload) (2001-2008), SAC-C (Satélite de Aplicaciones Cientificas-C) (2001-2013) and COSMIC (Constellation Observing System for Meteorology, Ionosphere and Climate) (2006-present). COSMIC is one of the RO missions with the greatest amount of atmospheric data available, mainly taking into account ionospheric information. In the RO technique, in general, the Abel retrieval is used to retrieve the refractive index. The Abel retrieval assumes a spherical symmetry of the atmosphere. When considering the electron density profiles, the main issue is related to regions with large horizontal gradients, where the spherical assumption presents the biggest degradation. In order to improve the ionospheric horizontal gradient used to retrieve electron density profiles, many researches have performed experiments using data from different sources. In this paper, we aimed to assess the electron density profiles over the Brazilian area (equatorial region), characterized by intense ionospheric variability, considering RO data and Global Ionospheric Maps (GIM). The data used is from COSMIC mission, in a period close to the last solar cycle peak (2013-2014). Ionosonde data were used as reference values to assess the RO with GIM aided data. Total Electron Content (TEC) data from GIM were used to estimate the variability of ionosphere between the ionosonde position and the profile locations. This research builds on a preliminary investigation related to the assessment of RO ionospheric profiles over a region under intense ionospheric variability, such as the Brazilian territory. Future works may take into consideration the use of other ionospheric information such as regional ionospheric maps, with higher resolution, and ionospheric tomography.</p>

Mutual radio occultation experiment between ExoMars Trace Gas Orbiter and Mars Express: feasibility study and preparation for the data analysis

2020 ◽  
Author(s):  
Bruno Nava ◽  
Anton Kashcheyev ◽  
Yenca Migoya-Orue ◽  
Sandro M. Radicella ◽  
Jacob Parrott ◽  
...  
Keyword(s):  
Data Processing ◽  
Electron Density ◽  
Doppler Shift ◽  
Radio Occultation ◽  
Trace Gas ◽  
Neutral Atmosphere ◽  
Ionospheric Electron Density ◽  
Density Profiles ◽  
Mars Express ◽  
Electron Density Profiles

<p>Radio Occultation is a very powerful technique to probe a planetary atmosphere, in providing vertical density profiles of the neutral atmosphere and ionosphere. The standard method uses a radio link at S and/or X band between a spacecraft and an Earth ground station. At Mars, such measurements are conducted since the 60s. The three most recent data sets are from MGS (1998-2006), Mars Express (since 2004) and MAVEN (since 2016). Taking advantage of two European spacecraft in orbit around Mars, the European Space Agency is currently preparing an experiment that consists of mutual radio occultations between Mars Express and the ExoMars Trace Gas Orbiter. Both spacecraft use UHF transceivers that are included primarily for communication between landers on the surface of Mars and the spacecraft, where the spacecraft act as relay orbiters to pass the data from the landers on to Earth. Therefore, these mutual occultations will be performed in the UHF range (centered around a frequency of 400 MHz). The feasibility of this technique on UHF was demonstrated between the NASA Mars Odyssey and Mars Reconnaissance Orbiters [Ao et al., 2015].</p><p>In this presentation, the advantages and challenges of this technique over the traditional spacecraft to Earth occultation measurements, the plans for conducting these experiments with Mars Express and the Trace Gas Orbiter, and the envisaged data processing technique will be briefly reviewed.</p><p>Before the data becomes available, and in order to prepare the data processing, a simulation-based strategy has been adopted to implement an algorithm able to retrieve vertical electron density profiles from Doppler shift measurements. More specifically, as a first step, simulated spacecraft orbits are calculated and a Chapman function is used to obtain the electron density of the Martian ionosphere. Subsequently, a numerical 3D ray-tracing algorithm [Kashcheyev et al., 2012] is applied to compute ray trajectories in the presence of the ionosphere and the relevant Doppler shift time series corresponding to the simulated radio occultation event. Then, assuming a spherical symmetry [Fjeldbo et al., 1971] for the ionosphere electron density, the (excess) Doppler data are converted to bending angles and impact parameters. Finally, the bending angle profile is inverted (through Abel integral) to a vertical refractivity profile, which, in turn, provides information about the ionospheric electron density.</p><p>For completeness, the simulation described above has been carried out with an exponential refractivity function defining the neutral atmosphere alone and with both the Chapman and the exponential refractivity functions to simulate the whole atmosphere of Mars.</p><p>The first results obtained by means of the mentioned approaches will be presented, with particular focus on the retrieval of the ionospheric electron density profiles.</p><p><strong>References</strong></p><p>Ao, C. O., C. D. Edwards Jr., D. S. Kahan, X. Pi, S. W. Asmar, and A. J. Mannucci (2015), A first demonstration of Mars crosslink occultation measurements, Radio Sci., 50, 997–1007, doi:10.1002/2015RS005750.</p><p>Fjeldbo, G., A. J. Kliore, and V. R. Eshleman (1971), The neutral atmosphere of Venus as studied with the Mariner V radio occultation experiments, Astron. J., 76, 123–140.</p><p>Kashcheyev, A., B. Nava, and S. M. Radicella (2012), Estimation of higher-order ionospheric errors in GNSS positioning using a realistic 3-D electron density model, Radio Sci., 47, RS4008, doi:10.1029/2011RS004976</p>

Electron density profiles above the F-layer

1973 ◽  
Vol 21 (9) ◽  
pp. 1581-1586
Author(s):  
Michael Anastassiadis ◽  
Georges Moraitis ◽  
Dimitris Matsoukas
Keyword(s):  
Electron Density ◽  
Density Profiles ◽  
Electron Density Profiles
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