Tomographic reconstruction of ionospheric electron density with European incoherent scatter radar verification

Raymund, T. D.; Pryse, S. E.; Kersley, L.; Heaton, J. A. T.

doi:10.1029/93rs01102

Cited by 59 publications

(42 citation statements)

References 8 publications

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“…Radio tomography has also been used to image the latitudinal structure of the trough. The method in this case suffers from limited ray-path geometry set by the configuration of the satellites and receivers (Yeh and Raymund, 1991) and requires a priori information to support the reconstruction process (Raymund et al, 1993). In another inversion application Mitchell and Spencer (2003) presented an algorithm using GPS observations that yielded the timeevolving, three-dimensional ionospheric electron concentration.…”

Section: Introductionmentioning

confidence: 99%

Modelling the main ionospheric trough using the Electron Density Assimilative Model (EDAM) with assimilated GPS TEC

et al. 2018

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Abstract. The main ionospheric trough is a large-scale spatial depletion in the electron density distribution at the interface between the high-and mid-latitude ionosphere. In western Europe it appears in early evening, progresses equatorward during the night, and retreats rapidly poleward at dawn. It exhibits substantial day-to-day variability and under conditions of increased geomagnetic activity it moves progressively to lower latitudes. Steep gradients on the trough-walls on either side of the trough minimum, and their variability, can cause problems for radio applications. Numerous studies have sought to characterize and quantify the trough behaviour.The Electron Density Assimilative Model (EDAM) models the ionosphere on a global scale. It assimilates observations into a background ionosphere, the International Reference Ionosphere 2007 (IRI2007), to provide a full 3-D representation of the ionospheric plasma distribution at specified times and days. This current investigation studied the capability of EDAM to model the ionosphere in the region of the main trough. Total electron content (TEC) measurements from 46 GPS stations in western Europe from September to December 2002 were assimilated into EDAM to provide a model of the ionosphere in the trough region. Vertical electron content profiles through the model revealed the trough and the detail of its structure. Statistical results are presented of the latitude of the trough minimum, TEC at the minimum and of other defined parameters that characterize the trough structure. The results are compared with previous observations made with the Navy Ionospheric Monitoring System (NIMS), and reveal the potential of EDAM to model the large-scale structure of the ionosphere.

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Section: Introductionmentioning

confidence: 99%

Modelling the main ionospheric trough using the Electron Density Assimilative Model (EDAM) with assimilated GPS TEC

et al. 2018

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“…Simultaneous TEC measurements were made from two stations by receiving phase coherent signals of 150 MHz and 400 MHz transmitted from a low Earth-orbiting Navy Navigational Satellite. Despite all the limitations of the experimental arrangement, the tomographic image could reveal the presence of a gradual, large-scale, northward electron density gradient, which was confirmed by independent measurements using the EISCAT radar (Raymund et al, 1993). Subsequently, several experiments were carried out in both the United Kingdom and Scandinavia, which demonstrated the potential of tomography to image large-scale ionospheric, features such as troughs in electron density found at auroral and subauroral latitudes (Kersley et al, 1997).…”

Section: Introductionmentioning

confidence: 65%

Simulation studies on the tomographic reconstruction of the equatorial and low-latitude ionosphere in the context of the Indian tomography experiment: CRABEX

et al. 2004

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Abstract. Equatorial ionosphere poses a challenge to any algorithm that is used for tomographic reconstruction because of the phenomena like the Equatorial Ionization Anomaly (EIA) and Equatorial Spread F (ESF). Any tomographic reconstruction of ionospheric density distributions in the equatorial region is not acceptable if it does not image these phenomena, which exhibit large spatial and temporal variability, to a reasonable accuracy. The accuracy of the reconstructed image generally depends on many factors, such as the satellite-receiver configuration, the ray path modelling, grid intersections and finally, the reconstruction algorithm. The present simulation study is performed to examine these in the context of the operational Coherent Radio Beacon Experiment (CRABEX) network just commenced in India. The feasibility of using this network for the studies of the equatorial and low-latitude ionosphere over Indian longitudes has been investigated through simulations. The electron density distributions that are characteristic of EIA and ESF are fed into various simulations and the reconstructed tomograms are investigated in terms of their reproducing capabilities. It is seen that, with the present receiver chain existing from 8.5 • N to 34 • N, it would be possible to obtain accurate images of EIA and the plasma bubbles. The Singular Value Decomposition (SVD) algorithm has been used for the inversion procedure in this study. As is known, by the very nature of ionospheric tomography experiments, the received data contain various kinds of errors, like the measurement and discretization errors. The sensitivity of the inversion algorithm, SVD in the present case, to these errors has also been investigated and quantified.

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“…These results encouraged the further analysis and development of this method (Raymund et al 1993;Foster et al 1994;Mitchell et al 1997;Yin et al 2004;Yizengaw et al 2007;Strangeways et al 2009;Amerian et al 2010). Generally, the tomographic models can be categorized as function based models and voxel based models.…”

Section: Introductionmentioning

confidence: 93%

“…Therefore, the application of regularization techniques for obtaining a reliable solution is needed. In the voxel based method; the ionosphere is developed into a set of cubic elements whose electron density is estimated using special reconstruction algorithms (Raymund et al 1993;Hansen et al 1997;Hernández-Pajares et al 1999;Colombo et al 1999). The rank deficiency of the system of simultaneous equations to be solved for estimating N e in every cubic element is an inherent property of the voxel based approach.…”

Section: Introductionmentioning

confidence: 99%

Development and analysis of 3D ionosphere modeling using base functions and GPS data over Iran

Razin

2015

Acta Geod Geophys

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In this study, a 3D-model of the electron density has been performed using the global positing system (GPS) measurements over Iran. 2D spherical harmonic functions and empirical orthogonal functions are used as base functions to model the horizontal and the vertical content of the electron density, respectively. The ionosonde data in Tehran (u = 35.7382°, k = 51.3851°) has been used for choosing an optimum value for the regularization parameter. To apply the method for constructing a 3D-image of the electron density, GPS measurements of the Iranian permanent GPS network (at 3-day in 2007) have been used. The instability of solution has been numerically analyzed and the Tikhonov method has been used for regularizing the solution. To come up with an optimum regularization parameter, the relative error in electron density profile computed from ionosonde measurements and their 3D model are minimized. The modeling region is between 24°to 40°N and 44°to 64°W. The result of 3D-Model has been compared to that of the international reference ionosphere model 2012 (IRI-2012). The data analysis shows that the latitudinal section of ionosphere electron density from 3D technique supports the expected time and height variations in ionosphere electron density. Moreover, these findings show that the height of maximum electron density is changed during the day and night and confirms the efficiency of multi-layer models in comparison to single-layer models. This method could recover 64-99 % of the ionosphere electron density.

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Tomographic reconstruction of ionospheric electron density with European incoherent scatter radar verification

Cited by 59 publications

References 8 publications

Modelling the main ionospheric trough using the Electron Density Assimilative Model (EDAM) with assimilated GPS TEC

Modelling the main ionospheric trough using the Electron Density Assimilative Model (EDAM) with assimilated GPS TEC

Simulation studies on the tomographic reconstruction of the equatorial and low-latitude ionosphere in the context of the Indian tomography experiment: CRABEX

Development and analysis of 3D ionosphere modeling using base functions and GPS data over Iran

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