scholarly journals A Method for Determining the Electron Density Distribution about the F2 Peak of the Ionosphere

1972 ◽  
Vol 25 (3) ◽  
pp. 293
Author(s):  
PL Dyson
Keyword(s):  
Density Distribution ◽  
Electron Density ◽  
Electron Density Distribution ◽  
Ionospheric Electron Density ◽  
Density Profiles ◽  
Electron Density Profiles ◽  
Limited Accuracy ◽  
Ground Echoes

A method is given for extending the analysis of topside ionograms to yield ionospheric electron density profiles down to and below hmax, the peak of the F2 layer, by analysis of the ground echoes. Calculations using model ionospheres indicate that the accuracy of the method is not seriously affected by the assumptions made or by the limited accuracy with which ionograms can be scaled.

X-Ray Characterization of Ag Impurities in Na1-xAgxCl

2008 ◽  
Vol 278 ◽  
pp. 33-44 ◽  
Author(s):  
Ramachandran Saravanan ◽  
K.S. Syed Ali ◽  
M. Prema Rani ◽  
R. Saravanan
Keyword(s):  
Density Distribution ◽  
Electron Density ◽  
Electron Density Distribution ◽  
Entropy Method ◽  
Data Sets ◽  
Density Profiles ◽  
X Ray ◽  
Density Maps ◽  
Electron Density Profiles

The alkali halide Na1-xAgxCl, with two different compositions (x = 0.03 and 0.10), was studied with regard to the Ag impurities in terms of the bonding and electron density distribution. X-ray single crystal data sets have been used for the purpose. The present analysis focused on the electron density distribution and hence the interaction between the atoms is clearly revealed by maximum entropy method (MEM) and multipole analyses. The bonding in these systems has been studied using two-dimensional MEM electron density maps on the (100) and (110) planes and onedimensional electron density profiles along the [100], [110] and [111] directions. The mid-bond electron densities between atoms in these systems are found to be 0.175 e/Å3 and 0.183 e/Å3, respectively, for Na0.97Ag0.03Cl and Na0.90Ag0.10Cl. Multipole analysis of the structure has been performed for these two systems, with respect to the expansion/contraction of the ion involved.

scholarly journals Simultaneous multiplicative column-normalized method (SMART) for 3-D ionosphere tomography in comparison to other algebraic methods

2016 ◽  
Vol 34 (1) ◽  
pp. 97-115 ◽  
Author(s):  
T. Gerzen ◽  
D. Minkwitz
Keyword(s):  
Density Distribution ◽  
Electron Density ◽  
Electron Density Distribution ◽  
Correction Method ◽  
Comparative Case Study ◽  
Physical Processes ◽  
Density Profiles ◽  
Electron Density Profiles ◽  
Algebraic Reconstruction Techniques

Abstract. The accuracy and availability of satellite-based applications like GNSS positioning and remote sensing crucially depends on the knowledge of the ionospheric electron density distribution. The tomography of the ionosphere is one of the major tools to provide link specific ionospheric corrections as well as to study and monitor physical processes in the ionosphere. In this paper, we introduce a simultaneous multiplicative column-normalized method (SMART) for electron density reconstruction. Further, SMART+ is developed by combining SMART with a successive correction method. In this way, a balancing between the measurements of intersected and not intersected voxels is realised. The methods are compared with the well-known algebraic reconstruction techniques ART and SART. All the four methods are applied to reconstruct the 3-D electron density distribution by ingestion of ground-based GNSS TEC data into the NeQuick model. The comparative case study is implemented over Europe during two periods of the year 2011 covering quiet to disturbed ionospheric conditions. In particular, the performance of the methods is compared in terms of the convergence behaviour and the capability to reproduce sTEC and electron density profiles. For this purpose, independent sTEC data of four IGS stations and electron density profiles of four ionosonde stations are taken as reference. The results indicate that SMART significantly reduces the number of iterations necessary to achieve a predefined accuracy level. Further, SMART+ decreases the median of the absolute sTEC error up to 15, 22, 46 and 67 % compared to SMART, SART, ART and NeQuick respectively.

scholarly journals Assessment of precision in ionospheric electron density profiles retrieved by GPS radio occultations

2014 ◽  
Vol 54 (11) ◽  
pp. 2249-2258 ◽  
Author(s):  
P. Alexander ◽  
A. de la Torre ◽  
R. Hierro ◽  
P. Llamedo
Keyword(s):  
Electron Density ◽  
Ionospheric Electron Density ◽  
Density Profiles ◽  
Electron Density Profiles

Ionospheric electron density profiles at sunrise-sunset

1985 ◽  
Vol 5 (7) ◽  
pp. 13-20 ◽  
Author(s):  
T.L. Gulyaeva
Keyword(s):  
Electron Density ◽  
Ionospheric Electron Density ◽  
Density Profiles ◽  
Electron Density Profiles

scholarly journals Recovery and Validation of Mars Ionospheric Electron Density Profiles from Viking Orbiter Radio Occultation Observations

2020 ◽  
Vol 1 (1) ◽  
pp. 14
Author(s):  
Paul Withers ◽  
Marianna Felici ◽  
Casey Flynn ◽  
Marissa F. Vogt
Keyword(s):  
Electron Density ◽  
Radio Occultation ◽  
Ionospheric Electron Density ◽  
Density Profiles ◽  
Electron Density Profiles ◽  
Viking Orbiter

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>

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