scholarly journals The Use of the Total Electron Content Measured by Navigation Satellites to Estimate Ionospheric Conditions

2016 ◽  
Vol 2016 ◽  
pp. 1-15 ◽  
Author(s):  
Olga Maltseva ◽  
Natalia Mozhaeva
Keyword(s):  
Total Electron Content ◽  
Critical Frequency ◽  
Global Scale ◽  
Maximum Density ◽  
Slab Thickness ◽  
Electron Content ◽  
Total Electron ◽  
Adequate Accuracy ◽  
Critical Frequency Fof2 ◽  
Experimental Values

Measurements of delays of the signals radiated by transmitters of navigational satellites allow us to obtain the total electron content (TEC). In addition, measurements of TEC allow solving problems such as development of local, regional, and global models of TEC and correction of ionospheric delay for increasing accuracy of positioning. Now, it is possible to set the task of calculation of critical frequency foF2 with the use of experimental values of TEC in a global scale. For this purpose it is necessary to know an equivalent slab thickness of the ionosphere τ which is a coefficient of proportionality between TEC and a maximum density of the ionosphere. The present paper is devoted to the analysis of investigation and utilization of this parameter. It is shown that (1) existing models of τ are not empirical and not always can provide an adequate accuracy of foF2 calculation, (2) experimental median τ(med) provides much larger accuracy of foF2 calculation than the empirical model and variations from day to day and allows filling gaps in the ionosonde data, and (3) it is possible to use a hyperbolic approximation and coefficient K(τ) for development of a global model of τ.

The ionospheric response to perturbation electric fields during the onset phase of geomagnetic storms

1992 ◽  
Vol 70 (7) ◽  
pp. 575-581 ◽  
Author(s):  
N. Jakowski ◽  
A. Jungstand ◽  
K. Schlegel ◽  
H. Kohl ◽  
K. Rinnert
Keyword(s):  
Total Electron Content ◽  
Electric Fields ◽  
Geomagnetic Storms ◽  
Slab Thickness ◽  
Electron Content ◽  
Total Electron ◽  
Total Electron Content Data ◽  
Critical Frequency Fof2 ◽  
Eiscat Radar ◽  
Onset Phase

The generation and propagation of ionospheric storms are studied by analyzing EISCAT radar, and vertical-sounding and total-electron-content data obtained under different geophysical conditions. Both, case studies as well as the average storm pattern of percentage deviations of different ionospheric parameters from their corresponding reference values such as total electron content, F2-layer critical frequency foF2, F2-layer height hmF2, and slab thickness τ indicate the action of a perturbation electric field during the first few hours during the onset phase of geomagnetic storms. Considering the onset phase of the storm on July 28–29, 1987 evidence has been found that high-latitude electric fields may penetrate to lower latitudes before the ring current has developed. In most cases this process is accompanied by a positive phase in the upper ionosphere and F2-layer ionization. Different mechanisms are assumed to be responsible for the daytime and nighttime behaviour, respectively. The negative phase propagates equatorward with velocities in the order of 70–350 m s−1 following a strong heating of the thermosphere and ionosphere due to the auroral electrojet.

scholarly journals Obtaining Ionospheric Conditions according to Data of Navigation Satellites

2015 ◽  
Vol 2015 ◽  
pp. 1-16 ◽  
Author(s):  
Olga Maltseva ◽  
Natalia Mozhaeva
Keyword(s):  
Critical Frequency ◽  
Bench Mark ◽  
Slab Thickness ◽  
Electron Content ◽  
Efficiency Coefficient ◽  
Low Latitude ◽  
Total Electron ◽  
Average Value ◽  
Middle Latitudes ◽  
Critical Frequency Fof2

Defining ionospheric conditions, the deviation of the observational value of the total electron content TEC(obs), measured by means of navigation satellites, from a median is a bench mark. According to more than 40 ionospheric stations during April 2014 it is shown that synchronism of change of deviations of TEC and critical frequency foF2 of the ionosphere is kept under quiet and moderate disturbed conditions. This fact allows to use a median of the equivalent slab thicknessτ(med) as a reliable calibration factor to calculate foF2 from TEC(obs). The efficiency coefficient of joint use ofτ(med) and TEC(obs) changes from 1.5 to 4 with average value 2.2 across the globe. The highest coefficient corresponds to middle latitudes, however the estimations obtained for high- and low-latitude areas indicate possibility to useτ(med) and TEC(obs) in these areas.

scholarly journals Neural network based model for global Total Electron Content forecasting

2020 ◽  
Vol 10 ◽  
pp. 11 ◽  
Author(s):  
Claudio Cesaroni ◽  
Luca Spogli ◽  
Angela Aragon-Angel ◽  
Michele Fiocca ◽  
Varuliator Dear ◽  
...  
Keyword(s):  
Neural Network ◽  
Total Electron Content ◽  
Geomagnetic Storms ◽  
Single Point ◽  
Global Scale ◽  
External Input ◽  
Electron Content ◽  
International Gnss Service ◽  
Total Electron ◽  
Grid Points

We introduce a novel empirical model to forecast, 24 h in advance, the Total Electron Content (TEC) at global scale. The technique leverages on the Global Ionospheric Map (GIM), provided by the International GNSS Service (IGS), and applies a nonlinear autoregressive neural network with external input (NARX) to selected GIM grid points for the 24 h single-point TEC forecasting, taking into account the actual and forecasted geomagnetic conditions. To extend the forecasting at a global scale, the technique makes use of the NeQuick2 Model fed by an effective sunspot number R12 (R12eff), estimated by minimizing the root mean square error (RMSE) between NARX output and NeQuick2 applied at the same GIM grid points. The novel approach is able to reproduce the features of the ionosphere especially during disturbed periods. The performance of the forecasting approach is extensively tested under different geospatial conditions, against both TEC maps products by UPC (Universitat Politècnica de Catalunya) and independent TEC data from Jason-3 spacecraft. The testing results are very satisfactory in terms of RMSE, as it has been found to range between 3 and 5 TECu. RMSE depend on the latitude sectors, time of the day, geomagnetic conditions, and provide a statistical estimation of the accuracy of the 24-h forecasting technique even over the oceans. The validation of the forecasting during five geomagnetic storms reveals that the model performance is not deteriorated during disturbed periods. This 24-h empirical approach is currently implemented on the Ionosphere Prediction Service (IPS), a prototype platform to support different classes of GNSS users.

scholarly journals Ionospheric total electron content and slab thickness determined in Australia

Radio Science ◽  
1997 ◽  
Vol 32 (4) ◽  
pp. 1635-1643 ◽  
Author(s):  
A. M. Breed ◽  
G. L. Goodwin ◽  
A-M. Vandenberg ◽  
E. A. Essex ◽  
K. J. W. Lynn ◽  
...  
Keyword(s):  
Total Electron Content ◽  
Slab Thickness ◽  
Electron Content ◽  
Total Electron ◽  
Ionospheric Total Electron Content

GPS satellite measurements: ionospheric slab thickness and total electron content

1995 ◽  
Vol 57 (14) ◽  
pp. 1723-1732 ◽  
Author(s):  
G.L. Goodwin ◽  
J.H. Silby ◽  
K.J.W. Lynn ◽  
A.M. Breed ◽  
E.A. Essex
Keyword(s):  
Total Electron Content ◽  
Slab Thickness ◽  
Electron Content ◽  
Satellite Measurements ◽  
Total Electron

scholarly journals Statistical analysis of ionospheric total electron content (TEC): long-term estimation of extreme TEC in Japan

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Michi Nishioka ◽  
Susumu Saito ◽  
Chihiro Tao ◽  
Daikou Shiota ◽  
Takuya Tsugawa ◽  
...  
Keyword(s):  
Total Electron Content ◽  
Communication Systems ◽  
Extreme Values ◽  
Cumulative Distribution ◽  
Propagation Path ◽  
Slab Thickness ◽  
Electron Content ◽  
Data Set ◽  
Total Electron ◽  
Ionospheric Total Electron Content

AbstractIonospheric total electron content (TEC) is one of the key parameters for users of radio-based systems, such as the Global Navigation Satellite System, high-frequency communication systems, and space-based remote sensing systems, since total ionospheric delay is proportional to TEC through the propagation path. It is important to know extreme TEC values in readiness for hazardous ionospheric conditions. The purpose of this study is to estimate extreme TEC values with occurrences of once per year, 10 years, and hundred years in Japan. In order to estimate the extreme values of TEC, a cumulative distribution function of daily TEC is derived using 22 years of TEC data from 1997 to 2018. The extreme values corresponding to once per year and 10 years are 90 and 110 TECU, respectively, in Tokyo, Japan. On the other hand, the 22-year data set is not sufficient to estimate the once-per-100-year value. Thus, we use the 62-year data set of manually scaled ionosonde data for the critical frequency of the F-layer (foF2) at Kokubunji in Tokyo. First, we study the relationship between TEC and foF2 for 22 years and investigate the slab thickness. Then the result is applied to the statistical distribution of foF2 data for 62 years. In this study, two methods are applied to estimate the extreme TEC value. In the first method, the distribution of slab thickness is artificially inflated to estimate extreme TEC values. In the second method, extreme slab thicknesses are applied to estimate extreme TEC values. The result shows that the once-per-100-year TEC is about 150–190 TECU at Tokyo. The value is also estimated to be 180–230 TECU in Kagoshima and 120–150 TECU in Hokkaido, in the southern and northern parts of Japan, respectively.

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