scholarly journals Electron density profile modeling

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.

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

2011 ◽  
Vol 29 (2) ◽  
pp. 229-236 ◽  
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.

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

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.

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

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.

scholarly journals Model-based reproduction and validation of the total spectrum of solar flare and their impact on the global environment at the X9.3 event of September 6, 2017

2020 ◽  
Author(s):  
Kyoko Watanabe ◽  
Hidekatsu Jin ◽  
Shohei Nishimoto ◽  
Shinsuke Imada ◽  
Toshiki Kawai ◽  
...  
Keyword(s):  
Solar Flare ◽  
Ionospheric Disturbance ◽  
Ionization Rate ◽  
Electron Content ◽  
Total Electron ◽  
Flare Loop ◽  
Earth’S Atmosphere ◽  
Earth's Atmosphere ◽  
The Difference ◽  
Good Agreement

Abstract We tried to reproduce the total electron content (TEC) variation in the Earth's atmosphere from the temporal variation of the solar flare spectrum of the X9.3 flare on September 6, 2017. The flare spectrum of the Flare Irradiance Spectral Model (FISM) which is most widely used and the flare spectrum from the 1D hydrodynamic model which considers the physics of plasma in the flare loop are used in the GAIA model which is a simulation model of the Earth's whole atmosphere and ionosphere, and calculate the difference of TEC. And then, we compared these results with the observed TEC. When we used the FISM flare spectrum, difference of TEC from the background was in a good agreement with the observation. On the other hand, when the flare spectrum of the 1D-hydro model was used, the result varied depending on the presence or absence of the background. This difference which depends on the models is thought to represent which EUV radiation is primarily responsible for increasing TEC. From the flare spectrum obtained from these models and the calculation result of TEC fluctuation using GAIA, it is considered that the enhancement in EUV emission about 15 to 35 nm is mainly contributes to increasing TEC rather than that of X-ray emission that has been thought to be mainly responsible for sudden ionospheric disturbance (SID). Also, from the altitude/wavelength distribution of the ionization rate of Earth's atmosphere by GAIA, it was found that EUV radiation of about 15–35 nm affects a wide altitude range of 120–300 km, and TEC enhancement is mainly caused by ionization of nitrogen molecules. (265 words)

Assessment of the IRI-2016 and modified IRI 2016 models in China: Comparison with GNSS-TEC and ionosonde data

2020 ◽  
Author(s):  
wen zhang ◽  
xingliang Huo ◽  
haojie Liu
Keyword(s):  
Signal Propagation ◽  
Electron Density Profile ◽  
Electron Content ◽  
Vertical Total Electron Content ◽  
Electron Densities ◽  
Iri Model ◽  
Total Electron ◽  
Observation Network ◽  
The Difference ◽  
Gnss Data

<p>Ionosphere is one of the main errors in the signal propagation of global navigation system satellite (GNSS), and it is also the key issue of space weather. The International Reference Ionosphere (IRI) is the most important empirical model described the ionospheric characteristics, and it provides the monthly averages of electron densities and vertical total electron content (VTEC) in the altitude range of 50km-2000km. The IRI-2016 model is the latest version. But some studies showed that the accuracy of the IRI model is not high enough in China due to the use of fewer data sources. This paper will assess the performance of IRI-2016 model in China, and a modified IRI 2016 model by adjusting the driving parameters IG and RZ index of IRI2016 model with GNSS TEC data are also investigated. In this contribution, GNSS data from the Crustal Movement Observation Network of China (CMONC) are used to estimate TEC values, and the ionosonde data from three stations are used as references for the ionospheric electron densities. Three ionosonde stations are located at Beijing (BP440, 40.3°N/116.2°E), Wuhan (WU430, 30.5°N/114.4°E) and Sanya (SA418, 18.3°N/ 109.6°E). The above data respectively cover a period of 6 days in the high year (2015) and low year (2019) of solar activity.</p><p>The study shows that the biggest reason for the difference (DTEC) between GPS-TEC and IRI2016-TEC in China is that the poor estimation of NmF2 and hmF2 by IRI model, and the driving parameters IG and RZ index of IRI2016 can be updated by constraining DTEC. Finally, the performance of the modified IRI-2016 model is improved by the updated IG and RZ indexes as the short-term driving values of ionospheric parameters. The analysis show that the modified IRI-2016 model is more accurate at estimating both the TEC and the electron density profile than the original model.</p>

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.

scholarly journals Using scale heights derived from bottomside ionograms for modelling the IRI topside profile

2005 ◽  
Vol 2 ◽  
pp. 293-297 ◽  
Author(s):  
B. W. Reinisch ◽  
X. Huang ◽  
A. Belehaki ◽  
R. Ilma
Keyword(s):  
Signal Analysis ◽  
Electron Density Profile ◽  
Electron Content ◽  
Satellite Measurements ◽  
Total Electron ◽  
Incoherent Scatter ◽  
Low Altitude ◽  
Satellite Beacon ◽  
Layer Peak ◽  
Good Agreement

Abstract. Groundbased ionograms measure the Chapman scale height HT at the F2-layer peak that is used to construct the topside profile. After a brief review of the topside model extrapolation technique, comparisons are presented between the modeled profiles with incoherent scatter radar and satellite measurements for the mid latitude and equatorial ionosphere. The total electron content TEC, derived from measurements on satellite beacon signals, is compared with the height-integrated profiles ITEC from the ionograms. Good agreement is found with the ISR profiles and with results using the low altitude TOPEX satellite. The TEC values derived from GPS signal analysis are systematically larger than ITEC. It is suggested to use HT , routinely measured by a large number of Digisondes around the globe, for the construction of the IRI topside electron density profile.

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