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

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.

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

Antarctic Science ◽

10.1017/s0954102096000430 ◽

1996 ◽

Vol 8 (3) ◽

pp. 297-302 ◽

Cited By ~ 4

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.

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The improved DGR analytical model of electron density height profile and total electron content in the ionosphere

Annals of Geophysics ◽

10.4401/ag-4130 ◽

1995 ◽

Vol 38 (1) ◽

Author(s):

S. M. Radicella ◽

M. L. Zhang

Keyword(s):

Electron Density ◽

Analytical Model ◽

Total Electron Content ◽

Density Profile ◽

Electron Density Profile ◽

Electron Content ◽

Height Profile ◽

Total Electron ◽

Improved Model

Tests of the analytical model of the electron density profile originally proposed by G, Di Giovanni and S.M. Radicella (DGR model) have shown the need to introduce improvements in order to obtain a model able to reproduce the ionosphere in a larger spectrum of geophysical and time conditions. The present paper reviews the steps toward such progress and presents the final formulation of the model. It gives also a brief re- view of tests of the improved model done by different authors.

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Gravity waves propagation in the thermosphere observed from electron density profile and total electron content measurements

Annals of Geophysics ◽

10.4401/ag-3830 ◽

1997 ◽

Vol 40 (6) ◽

Author(s):

M. Anzidei ◽

C. Bianchi ◽

L. Ciraolo ◽

M. Pezzopane ◽

C. Scotto

Keyword(s):

Electron Density ◽

Total Electron Content ◽

Gravity Waves ◽

Density Profile ◽

Electron Density Profile ◽

Electron Content ◽

Gps Receiver ◽

Total Electron ◽

Waves Propagation ◽

Short Periodicity

Ionospheric observations with five minute intervals between ionograms were made during a campaign from 19th to 23rd June 1996 at the Rome station (41.8N, 12.5E). The data obtained from ionospheric vertical sounding have been analysed together with the Total Electron Content (TEC) data obtained by the GPS receiver measurements. Both the apparatus were installed in the same station. Short periodicity phenomena occurring in the considered period were observed and interpreted as resulting from the propagation of AGWs in the thermosphere. TEC and electron density were then analysed during AGWs activity.

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Study of Total Electron Content and Electron Density Profile from Satellite Observations During Geomagnetic Storms

Journal of Nepal Physical Society ◽

10.3126/jnphyssoc.v5i1.26932 ◽

2019 ◽

Vol 5 (1) ◽

pp. 59-66

Author(s):

B. B. Rana ◽

N. P. Chapagain ◽

B. Adhikari ◽

D. Pandit ◽

K. Pudasainee ◽

...

Keyword(s):

Solar Wind ◽

Electron Density ◽

Total Electron Content ◽

Density Profile ◽

Geomagnetic Storms ◽

Electron Density Profile ◽

Wind Pressure ◽

Electron Content ◽

Total Electron ◽

Geomagnetic Indices

Total Electron Content (TEC) and electron density profile are the key parameters in the mitigation of ionospheric effects on radio wave communication system. In this study, the variations of TEC and electron density profile have been analyzed using satellite data from four different latitude-longitude sectors (13°N -17°N, 88°E - 98°E), (30°N - 50°N, 95°W - 120°W), (26°S - 29°S, 163°W - 167°W,) and (45°S - 60°S, 105°W-120°W) during different geomagnetic storms. The interplanetary magnetic field (Bz), solar wind velocity (Vsw), solar wind pressure (Psw) and geomagnetic indices, aurora index -AE, Kp and disturbed stormed time index (Dst) are also analyzed to distinguish their effects on TEC and electron density. The geomagnetic indices and solar wind parameters are correlated with the TEC and electron density. The study showed that the value of TEC and electron density vary significantly with different latitude, longitude, altitude and solar activities. The result also concludes that the electron density profile increases with the altitude, acquired peak value around 250km-300km and decreased beyond the altitude of 300 km.

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Topside ionospheric vertical electron density profile reconstruction using GPS and ionosonde data: possibilities for South Africa

Annales Geophysicae ◽

10.5194/angeo-29-229-2011 ◽

2011 ◽

Vol 29 (2) ◽

pp. 229-236 ◽

Cited By ~ 15

Author(s):

P. Sibanda ◽

L. A. McKinnell

Keyword(s):

South Africa ◽

Electron Density ◽

Geographic Location ◽

Electron Density Profile ◽

Empirical Modeling ◽

Topside Ionosphere ◽

Electron Content ◽

Total Electron ◽

Gps Tec ◽

Profile Reconstruction

Abstract. Successful empirical modeling of the topside ionosphere relies on the availability of good quality measured data. The Alouette, ISIS and Intercosmos-19 satellite missions provided large amounts of topside sounder data, but with limited coverage of relevant geophysical conditions (e.g., geographic location, diurnal, seasonal and solar activity) by each individual mission. Recently, methods for inferring the electron density distribution in the topside ionosphere from Global Positioning System (GPS)-based total electron content (TEC) measurements have been developed. This study is focused on the modeling efforts in South Africa and presents the implementation of a technique for reconstructing the topside ionospheric electron density (Ne) using a combination of GPS-TEC and ionosonde measurements and empirically obtained Upper Transition Height (UTH). The technique produces reasonable profiles as determined by the global models already in operation. With the added advantage that the constructed profiles are tied to reliable measured GPS-TEC and the empirically determined upper transition height, the technique offers a higher level of confidence in the resulting Ne profiles.

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Electron density profile modeling

Annals of Geophysics ◽

10.4401/ag-3990 ◽

1996 ◽

Vol 39 (3) ◽

Author(s):

R. G. Ezquer ◽

M. Mosert de Gonzalez ◽

T. Heredia

Keyword(s):

Electron Density ◽

Characteristic Point ◽

Base Point ◽

Electron Density Profile ◽

Electron Content ◽

Total Electron ◽

F Region ◽

Bottom Side ◽

The Difference ◽

Good Agreement

The Base Point Model (BPM) is used to model the electron density (N) profile in the ionosphere, This model assumes two Chapman profile expressions one for the bottomside and one for the topside, and requires a characteristic point called "F region base point". The comparison among the modeled and experimental bottom-side N profiles obtained from Tucuman (26,9°S; 65.4°W) ionosonde shows that, in general, there is a very good agreement within 30 km below the height of the maximum N(hm). Cases with a very good agreement for the entire N-profile are observed. The study of the electron content below hm and the Total Electron Content (TEC) measured over Tucuman shows that, the difference among predicted and measured TEC is due to the disagreement in the topside N-profile more than that observed in the bottomside N-profile.

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

Natural Hazards and Earth System Science ◽

10.5194/nhess-11-2341-2011 ◽

2011 ◽

Vol 11 (8) ◽

pp. 2341-2353 ◽

Cited By ~ 13

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.

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Estimation of the electron density profile in the D region from rocket measurement of VLF signals from a ground based transmitter

Electrical Engineering in Japan ◽

10.1002/ecja.4400641110 ◽

1981 ◽

Vol 64 (11) ◽

pp. 68-74

Author(s):

Isamu Nagano ◽

Masayoshi Mambo ◽

Tetsuo Fukami ◽

Koji Namba ◽

Iwane Kimura

Keyword(s):

Electron Density ◽

Density Profile ◽

Electron Density Profile ◽

Rocket Measurement ◽

D Region

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Radial density profile and stability of capillary discharge plasma waveguides of lengths up to 40 cm

High Power Laser Science and Engineering ◽

10.1017/hpl.2021.6 ◽

2021 ◽

Vol 9 ◽

Author(s):

M. Turner ◽

A. J. Gonsalves ◽

S. S. Bulanov ◽

C. Benedetti ◽

N. A. Bobrova ◽

...

Keyword(s):

Laser Pulse ◽

Electron Density ◽

Density Profile ◽

Pulse Propagation ◽

Spot Size ◽

Capillary Discharge ◽

Electron Density Profile ◽

Plasma Waveguide ◽

Wakefield Acceleration ◽

Plasma Wakefield

Abstract We measured the parameter reproducibility and radial electron density profile of capillary discharge waveguides with diameters of 650 $\mathrm{\mu} \mathrm{m}$ to 2 mm and lengths of 9 to 40 cm. To the best of the authors’ knowledge, 40 cm is the longest discharge capillary plasma waveguide to date. This length is important for $\ge$ 10 GeV electron energy gain in a single laser-driven plasma wakefield acceleration stage. Evaluation of waveguide parameter variations showed that their focusing strength was stable and reproducible to $<0.2$ % and their average on-axis plasma electron density to $<1$ %. These variations explain only a small fraction of laser-driven plasma wakefield acceleration electron bunch variations observed in experiments to date. Measurements of laser pulse centroid oscillations revealed that the radial channel profile rises faster than parabolic and is in excellent agreement with magnetohydrodynamic simulation results. We show that the effects of non-parabolic contributions on Gaussian pulse propagation were negligible when the pulse was approximately matched to the channel. However, they affected pulse propagation for a non-matched configuration in which the waveguide was used as a plasma telescope to change the focused laser pulse spot size.

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