Electron Density Reconstruction by Ionospheric Tomography from the combination of GNSS and Upcoming LEO Constellations

2021 ◽  
Author(s):  
Xiaodong Ren ◽  
Dengkui Mei ◽  
Xiaohong Zhang ◽  
Mohamed Freeshah ◽  
Si Xiong
Keyword(s):  
Electron Density ◽  
Ionospheric Tomography

scholarly journals EISCAT verification in the development of ionospheric tomography

1996 ◽  
Vol 14 (12) ◽  
pp. 1413-1421 ◽  
Author(s):  
I. K. Walker ◽  
J. A. T. Heaton ◽  
L. Kersley ◽  
C. N. Mitchell ◽  
S. E. Pryse ◽  
...  
Keyword(s):  
Electron Density ◽  
Tomographic Reconstruction ◽  
Tomographic Image ◽  
High Latitudes ◽  
Ionospheric Electron Density ◽  
Ionospheric Tomography ◽  
Eiscat Radar

Abstract. This paper highlights the important role played by the EISCAT radar for verification in the development of tomographic techniques to produce images of ionospheric electron density. A brief review is given of some of the stages in the application of tomographic reconstruction techniques to the ionosphere. Results are presented to illustrate the effectiveness of the method in imaging ionospheric structures at high latitudes. In addition, the results include the first tomographic image of the ionosphere for a region extending from mid-latitudes over mainland Scandinavia to high latitudes above Svalbard.

scholarly journals A New Method for Ionospheric Tomography and Its Assessment by Ionosonde Electron Density, GPS TEC, and Single-Frequency PPP

2019 ◽  
Vol 57 (5) ◽  
pp. 2571-2582 ◽  
Author(s):  
Fabricio dos Santos Prol ◽  
Paulo de Oliveira Camargo ◽  
Manuel Hernandez-Pajares ◽  
Marcio Tadeu de Assis Honorato Muella
Keyword(s):  
Electron Density ◽  
New Method ◽  
Single Frequency ◽  
Ionospheric Tomography ◽  
Gps Tec

Toward ionospheric tomography in Antarctica: first steps and comparison with dynasonde observations

1996 ◽  
Vol 8 (3) ◽  
pp. 297-302 ◽  
Author(s):  
J.A.T. Heaton ◽  
G.O.L. Jones ◽  
L. Kersley
Keyword(s):  
Electron Density ◽  
Total Electron Content ◽  
Satellite System ◽  
Electron Density Profile ◽  
Electron Content ◽  
Total Electron ◽  
Ionospheric Tomography ◽  
Contour Maps ◽  
Tomographic Method ◽  
Independent Observations

Total electron content (TEC) measurements obtained at two Antarctic stations over nine months beginning early in 1994 have been analysed as a first step to performing ionospheric tomography. Two receiving systems were deployed at the Faraday and Halley research stations operated by the British Antarctic Survey to monitor signals from a random selection of passes of satellites in the Navy Navigational Satellite System. The resultant measurements of total electron content have been inverted and combined with ionosonde measurements of true height and foF2 to yield two-dimensional contour maps of ionospheric electron density. In spite of the poor geometry of the observations, some 130 satellite passes were found to be suitable for reconstruction using the techniques developed for ionospheric tomography. The contour maps of plasma density have been compared with independent observations of the vertical electron density profile measured by the dynasonde ionospheric sounder located at Halley. An example is presented of a deep trough investigated by the technique, illustrating the potential of the tomographic method for study of an extended spatial region of the ionosphere over inhospitable terrain.

scholarly journals Neural network based tomographic approach to detect earthquake-related ionospheric anomalies

2011 ◽  
Vol 11 (8) ◽  
pp. 2341-2353 ◽  
Author(s):  
S. Hirooka ◽  
K. Hattori ◽  
M. Nishihashi ◽  
T. Takeda
Keyword(s):  
Neural Network ◽  
Electron Density ◽  
Electron Content ◽  
Total Electron ◽  
Ionospheric Tomography ◽  
Maximum Electron Density ◽  
Southern Side ◽  
Global Ionosphere Map ◽  
Residual Minimization ◽  
Tomographic Approach

Abstract. A tomographic approach is used to investigate the fine structure of electron density in the ionosphere. In the present paper, the Residual Minimization Training Neural Network (RMTNN) method is selected as the ionospheric tomography with which to investigate the detailed structure that may be associated with earthquakes. The 2007 Southern Sumatra earthquake (M = 8.5) was selected because significant decreases in the Total Electron Content (TEC) have been confirmed by GPS and global ionosphere map (GIM) analyses. The results of the RMTNN approach are consistent with those of TEC approaches. With respect to the analyzed earthquake, we observed significant decreases at heights of 250–400 km, especially at 330 km. However, the height that yields the maximum electron density does not change. In the obtained structures, the regions of decrease are located on the southwest and southeast sides of the Integrated Electron Content (IEC) (altitudes in the range of 400–550 km) and on the southern side of the IEC (altitudes in the range of 250–400 km). The global tendency is that the decreased region expands to the east with increasing altitude and concentrates in the Southern hemisphere over the epicenter. These results indicate that the RMTNN method is applicable to the estimation of ionospheric electron density.

Electron density structures in the polar cap imaged by ionospheric tomography

1998 ◽  
Vol 22 (9) ◽  
pp. 1385-1389 ◽  
Author(s):  
S.E Pryse ◽  
L Kersley ◽  
M.J Williams
Keyword(s):  
Electron Density ◽  
Polar Cap ◽  
Ionospheric Tomography

scholarly journals A Review of Voxel-Based Computerized Ionospheric Tomography with GNSS Ground Receivers

2021 ◽  
Vol 13 (17) ◽  
pp. 3432
Author(s):  
Weijun Lu ◽  
Guanyi Ma ◽  
Qingtao Wan
Keyword(s):  
Electron Density ◽  
Algebraic Method ◽  
Coefficient Matrix ◽  
Satellite System ◽  
Space Physics ◽  
Event Analysis ◽  
Radio Waves ◽  
Ionospheric Tomography ◽  
Additional Information ◽  
Computerized Ionospheric Tomography

Ionized by solar radiation, the ionosphere causes a phase rotation or time delay to trans-ionospheric radio waves. Reconstruction of ionospheric electron density profiles with global navigation satellite system (GNSS) observations has become an indispensable technique for various purposes ranging from space physics studies to radio applications. This paper conducts a comprehensive review on the development of voxel-based computerized ionospheric tomography (CIT) in the last 30 years. A brief introduction is given in chronological order starting from the first report of CIT with simulation to the newly proposed voxel-based algorithms for ionospheric event analysis. The statement of the tomographic geometry and voxel models are outlined with the ill-posed and ill-conditioned nature of CIT addressed. With the additional information from other instrumental observations or initial models supplemented to make the coefficient matrix less ill-conditioned, equation constructions are categorized into constraints, virtual data assimilation and multi-source observation fusion. Then, the paper classifies and assesses the voxel-based CIT algorithms of the algebraic method, statistical approach and artificial neural networks for equation solving or electron density estimation. The advantages and limitations of the algorithms are also pointed out. Moreover, the paper illustrates the representative height profiles and two-dimensional images of ionospheric electron densities from CIT. Ionospheric disturbances studied with CIT are presented. It also demonstrates how the CIT benefits ionospheric correction and ionospheric monitoring. Finally, some suggestions are provided for further research about voxel-based CIT.

scholarly journals Probing discrete auroral arcs by ionospheric tomography

1998 ◽  
Vol 16 (5) ◽  
pp. 574-582 ◽  
Author(s):  
J. Moen ◽  
S. T. Berry ◽  
L. Kersley ◽  
B. Lybekk
Keyword(s):  
Electron Density ◽  
Optical Observations ◽  
Precipitation Event ◽  
Radio Science ◽  
Ionospheric Tomography ◽  
Ionospheric Physics ◽  
Radio Signals ◽  
A Chain ◽  
Auroral Phenomena ◽  
Auroral Arcs

Abstract. Optical observations of 557.7 nm and 630.0 nm emissions from discrete auroral arcs in the post-noon sector have been related to localised field-aligned enhancements in the spatial distribution of E- and F-layer electron density respectively seen in images reconstructed by ionospheric tomography. Results from two case studies are presented in which meridian scanning photometer and all-sky camera observations on Svalbard have been compared to electron-density structures found by tomographic inversion of measurements made by reception of radio signals at a chain of four stations at high latitude. The F-layer features are long-lived and show exact correspondence to the red-line emissions. Transient arcs in green-line intensity result in E-region structures that are resolved in one case, but not in another where the dynamic auroral forms are separated by less than one degree of latitude. The signature of an inverted-V precipitation event is clearly evident in one example.Key words. Ionosphere (Auroral ionosphere) · Magnetospheric physics (Auroral phenomena) · Radio science (Ionospheric physics)

scholarly journals Determination of the vertical electron-density profile in ionospheric tomography: experimental results

1997 ◽  
Vol 15 (6) ◽  
pp. 747-752 ◽  
Author(s):  
C. N. Mitchell ◽  
L. Kersley ◽  
J. A. T. Heaton ◽  
S. E. Pryse
Keyword(s):  
Electron Density ◽  
Density Profile ◽  
Vertical Profile ◽  
Fundamental Problem ◽  
Selection Criterion ◽  
Electron Density Profile ◽  
Electron Content ◽  
Reconstruction Process ◽  
Total Electron ◽  
Ionospheric Tomography

Abstract. The reconstruction of the vertical electron-density profile is a fundamental problem in ionospheric tomography. Lack of near-horizontal ray paths limits the information available on the vertical profile, so that the resultant image of electron density is biased in a horizontal sense. The vertical profile is of great importance as it affects the authenticity of the entire tomographic image. A new method is described whereby the vertical profile is selected using relative total-electron-content measurements. The new reconstruction process has been developed from modelling studies. A range of background ionospheres, representing many possible peak heights, scale heights and electron densities are formed from a Chapman profile on the bottomside with a range of topside profiles. The iterative reconstruction process is performed on all of these background ionospheres and a numerical selection criterion employed to select the final image. The resulting tomographic images show excellent agreement in electron density when compared with independent verification provided by the EISCAT radar.

White-Light Coronal Structures: Streamers and CMEs

1994 ◽  
Vol 144 ◽  
pp. 82
Author(s):  
E. Hildner
Keyword(s):  
Emission Line ◽  
Electron Density ◽  
White Light ◽  
Coronal Mass Ejections ◽  
X Rays ◽  
Solar Cycles ◽  
Temperature Function ◽  
X Ray ◽  
Eclipse Observations ◽  
Coronal Structures

AbstractOver the last twenty years, orbiting coronagraphs have vastly increased the amount of observational material for the whitelight corona. Spanning almost two solar cycles, and augmented by ground-based K-coronameter, emission-line, and eclipse observations, these data allow us to assess,inter alia: the typical and atypical behavior of the corona; how the corona evolves on time scales from minutes to a decade; and (in some respects) the relation between photospheric, coronal, and interplanetary features. This talk will review recent results on these three topics. A remark or two will attempt to relate the whitelight corona between 1.5 and 6 R⊙to the corona seen at lower altitudes in soft X-rays (e.g., with Yohkoh). The whitelight emission depends only on integrated electron density independent of temperature, whereas the soft X-ray emission depends upon the integral of electron density squared times a temperature function. The properties of coronal mass ejections (CMEs) will be reviewed briefly and their relationships to other solar and interplanetary phenomena will be noted.

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