Pdf time varying computerized ionospheric tomography. Pdf our work addresses ionospheric radio tomography rt based on the low orbital lo and high orbital ho navigational systems and the radio. Constrained simultaneous algebraic reconstruction technique. At first sight, tomography appears to be the right choice.
We use a wavelet neural network with a particle swarm optimization training algorithm to solve pixelbased ionospheric tomography. A hybrid reconstruction algorithm for 3d ionospheric. At present, in the problems of ray radio tomography of the ionosphere, iterative algorithms are most popular, although noniterative algorithms are also used. An improved ionospheric tomography algorithm is developed for the tomographic reconstruction of the ionospheric electron density distribution based on the automatic search technology of relaxation. A notable example of applications is the reconstruction of computed tomography ct where crosssectional images of patients are obtained. Since existing algorithms are static reconstruction algorithms, the motion of the ionosphere becomes a source of image. This paper presents a modelindependent algorithm for tomography of the. Aug 12, 2015 tomographic reconstruction of ionospheric electron density during the storm of 56 august 2011 using multisource data skip to main content thank you for visiting. Computerized ionospheric tomography with the iri model orhan arikan a, feza arikan b, cemil b.
Tomographic reconstruction of ionospheric electron density. Regardless of the tomographic algorithm in use, the infor mation provided by satellite to ground measurements is poor. The rcm is a fast, efficient, and numerically stable ionospheric tomography algorithm. Ionosphere tomography is a typical illposed problem, and using the ionosphere priori information as the constraints to improve the state of normal equation is an effective approach to solve this. Adaptive smoothness constraint ionospheric tomography algorithm. This paper presents a new ionospheric reconstruction algorithm called the residual correction method rcm. Electron density profiles derived from groundbased gps. Ionospheric data assimilation methods for geodetic. A density value at a single grid cell provides sufficient additional a priori information to constrain the imaging of a horizontally stratified ionosphere. A new ionospheric estimation algorithm for sbas combining kriging and tomography juan blanch, todd walter, and per enge. Application of generalized singular value decomposition to ionospheric tomography k. Meanwhile, some efficient algorithms have been proposed to improve the accuracy and resolution of the reconstructed ionospheric images 20,21. We then discuss the use of tikhonov 1963 regularization in all four algorithms gcgls, mart,rl, and lspd and pre. These tecmeasurements can be inverted using a tomographic algorithm, after which the reconstructions can be compared with the truth to assess accuracy.
Orthogonal decomposition framework for ionospheric tomography algorithms orthogonal decomposition framework for ionospheric tomography algorithms sutton, eric. A new twostep algorithm for ionospheric tomography solution. In this paper, a regional ionospheric mapping and tomography rimt tool was developed, which can be used to retrieve 2d tec and 3d ionospheric electron density profiles using groundbased or spaceborne gps measurements. Analysis and validation of gpsmet radio occultation data. Pdf tomography reconstruction of ionospheric electron density. A hybrid reconstruction algorithm for 3d ionospheric tomography debao wen, yunbin yuan, jikun ou, kefei zhang, and kai liu abstractin this paper, a hybrid reconstruction algorithm hra is presented to solve the illposed inverse problem associated with 3d ionospheric stochastic tomography. According to the actual detecting condition of sparse receiver and limited projecting angle, polynomial interpolation method and projecting angle expansion. Ionospheric total electron content tec measurements, obtained simultaneously at several locations, can be processed using computerized tomography ct algorithms to. This paper compares the performance of three different reconstruction algorithms used for tomographic imaging of the ionosphere. Abstract an improved ionospheric tomography algorithm is developed for the tomographic reconstruction of the ionospheric electron density. However, the single layer model only reflects the variation of the ionosphere in the horizontal plane but neglects the variation along the altitude. Alternating minimization algorithms for transmission. The study highlights the critical role of the range of the background input to the algorithms.
Robertson and gerald l mader national geodetic survey, nosnoaa and cooperative institute for research in environmental sciences cires and noaa space environment center university of coloradonoaa, boulder, colorado 803090216, usa. According to the actual detecting condition of sparse receiver and limited projecting angle, polynomial interpolation method and projecting angle expansion method. A new ionospheric tomographic algorithm taking into. This was conventional tomographic imaging where the line integral data were approximated into a plane and inverted to reveal the electron density.
This new method is called ionospheric tomography based on the neural network itnn. Simulation studies on the tomographic reconstruction of. A realistic simulation framework to evaluate ionospheric. Thus, the observation equationobtainedusingdualfrequencycodemeasurements. Na, hua lee, and jian shen tomographic imaging of the ionosphere using bidirectional extrapolation algorithm, proc. Related electron energization in the ionosphere and the plasma sheet. Stanford university abstract one can divide the existing ionospheric methods for sbas in two categories. Reconstruction algorithm of computerized ionospheric tomography. A new ionospheric tomographic algorithm taking into account the variation of the ionosphere. To overcome this geometric deficiency, constraints or initial conditions of the ionosphere are imposed in the reconstruction method wen et al. Development and applications of ionospheric tomography. Rowaction methods for huge and sparse systems and their applications. Computerized tomography provides valuable information for imaging the ionospheric electron density distribution. The nature of these limitations is described in this paper.
The test cases chosen make use of experimental electron content observations obtained from a meridional chain of receivers in scandinavia at times when the european incoherent scatter radar facility provided independent measurements of electron density for. Tomographic reconstruction is a type of multidimensional inverse problem where the challenge is to yield an estimate of a specific system from a finite number of projections. Department of geomatics engineering the university of calgary calgary, alberta, canada t2n 1n4. This paper presents a modelindependent algorithm for tomography of the ionosphere. Some inversion techniques are based on 2 minimization algorithms i. A new approach is proposed for cit that aims to permit sparsity in the reconstruction coef. Numerical simulations to assess art and mart performance for. Computerized tomography ct techniques can be used to produce a twodimensional image of the electron density in the ionosphere.
To resolve it, an adaptive smoothness constraint ionospheric tomography algorithm is proposed in this work. Prior knowledge consists of the following pieces of information. Applying the technique of computer tomography to ionosphere detection, computerized ionospheric tomography cit can produce the large scale distribution of electron density in a two dimentional longitudinal section of ionosphere. Development and applications of ionospheric tomography ideals. Tomographic analysis of ionosphere and plasmasphere. An improved iterative algorithm for ionospheric tomography. The mathematical basis for tomographic imaging was laid down by johann radon. Pdf ionospheric tomography using navigation systems. Ionospheric correction using tomography stanford university. The new algorithm performs an adaptive adjustment for the constrained weight coefficients of the tomography system. On the other hand, the performance of the existing reconstruction algorithms based on the adaptive adjustment of the relaxation parameters needs to be further improved.
Tikhonov regularization and a standard approach is implemented here using spherical harmonics as a reference to compare the new method. Ionospheric tomography inverse algorithms are usually an illconditioned problem because the geometric distribution of continuously operating reference gps stations is not ideal for this task. A new ionospheric estimation algorithm for sbas combining. In addition, a unified discussion of some of the various reconstruction algorithms is presented. Due to the nonuniform and sparsity of ground gnss observation stations, the input data of the. A comparison of reconstruction techniques used in ionospheric. There are numerous algorithms, both direct and iterative, that solve sles 4 and 5. In this paper, a new fourier domain reconstruction algorithm is presented which utilizes the information contained in the known region of the spectrum to estimate the frequency samples in the missingcone area. The threedimensional ionospheric tomography algorithm with side rays was first presented in 2016 and applied to gnss water vapor tomography yao et al.
For emissions produced by radiative recombination of electrons. A modified threedimensional ionospheric tomography algorithm. Ionospheric tomography algorithms, international journal of. Reconstruction algorithm of computerized ionospheric. In other words, no particular algorithm is able to give a unique solution to the problem of ionospheric tomography. Erol c a bilkent university, department of electrical and electronics engineering, bilkent ankara 06800, turkey b hacettepe university, department of electrical and electronics engineering, beytepe ankara 06800, turkey. Computerized ionospheric tomography with the iri model.
State key laboratory of geodesy and earths dynamics, institute of geodesy and geophysics, chinese academy of sciences, wuhan 430077, china. Application of generalized singular value decomposition to. Global positioning system gps radio occultation signals received by a low earth orbit leo satellite provide information about the global distribution of electron density in the ionosphere. Introduction investigationsof ionospheric spatial plasma distributions are necessary in order to study the ionosphere and the physics of its processes. Therefore the former method usually method has higher time resolution than the latter one. Bayesian statistical ionospheric tomography improved by. Previous studies mainly focused on improving inversion algorithms to solve the illposed inversion functions, but they cannot be applied generally, moreover, the illposed problem has not been solved radically.
Convergent incremental optimization transfer algorithms. I is the brightness in units of rayleighs megaphotons s. In order to cope with such illconditioning, a new tomographic algorithm, termed twostep algorithm tsa, is presented. Algorithms and basis functions in tomographic reconstruction. Since the sle is underdetermined, we incorporate a prior information initial guess through the use of local time dependent empirical orthogonal functions eofs derived from international reference ionosphere iri2016 model.
Precise ionosphere modeling using regional gps network data. The ionosphere, as a medium for radio wave propagation, essentially influences the operation. Adaptive smoothness constraint ionospheric tomography. A new twostep algorithm for ionospheric tomography. Fullorbit ultraviolet ionospheric tomography and applications. Precise ionosphere modeling using regional gpsnetwork data. Erol c a bilkent university, department of electrical and electronics engineering, bilkent ankara 06800, turkey b hacettepe university, department of electrical and electronics engineering, beytepe ankara 06800, turkey c tubitak uekae, kavaklidere, ankara 06100, turkey. As a result, the ionosphere tomography method would allow for more precise exploration of the ionospheric characteristics and. A notable example of applications is the reconstruction of computed tomography ct where. Tomographic algorithms direct inversion discrete inverse theory dit many different mathematical techniques have been used by different workers finding an appropriate background ionosphere to initialise any algorithm is the key to ionospheric tomography use extension of dit method of fremouw et al.
Gridbased tomography, electron density, ionospheric profile, chapman function, gnss. Computerized ionospheric tomography cit is a technique to reconstruct the 2d, 3d or 4d ionospheric images bust and mitchell, 2008, razin, 2016. We applied the computerized ionospheric tomography cit algorithm to the tec dataset from this gps network for monitoring the regional ionosphere over. Tomographic reconstruction of ionospheric electron density during the storm of 56 august 2011 using multisource data skip to main content thank you for visiting. Rowaction methods for huge and sparse systems and their. Compared with traditional simultaneous algebraic reconstruction, this method facilitates. Ionospheric data assimilation methods for geodetic applications paul s.
Tomographic imaging of the ionosphere using bidirectional. The midas algorithms are based upon the oceanographic imaging techniques of munk and wunsch 1979. Computerized ionospheric tomography algorithms traditionally ignore the time variations of ionospheric distributions. Sensors 2020, 20, 2404 3 of 17 is the length of the th path in the th voxel. Orthogonal decomposition framework for ionospheric tomography.
To the lower ionosphere, occhipinti setted up a new method based on the raytracing tool tdr to invert the propagation time. A modelindependent algorithm for ionospheric tomography. Ionospheric tomography reconstruction based on global navigation satellite system observations is usually an illposed problem. Owing to the system configuration, the resolving capability of these systems is still limited. We examine two radio occultation inversion algorithms. Huo xingliang 1, yuan yunbin 1, ou jikun 1, li ying 1, li zishen 2, wang ningbo 1. Usually the voxel technique needs less gps measurements to model than the tomography technique required. Pdf an improved iterative algorithm for ionospheric.
This item appears in the following collections graduate dissertations and theses at illinois graduate theses and dissertations at illinois. In ionospheric tomography, when used to reconstruct the electron density pro. A case of study in a geomagnetic storm shuanggen jin1 and rui jin1, 2 1 shanghai astronomical observatory, chinese academy of sciences, shanghai 200030, china 2 graduate university of the chinese academy of sciences, beijing 49, china email. However, the efficiency of the ionospheric tomography is an issue. Dissertations and theses electrical and computer engineering. Ionospheric imaging using computerized tomography ideals. Satellite radio probing and radio tomography of the ionosphere. In this paper, isr scans are used to produce computer representations of the ionosphere that are then used to test an ionospheric imaging algorithm, with the aim of evaluating the accuracy and. Using sparse regularization for multiresolution tomography. In this study, a set of basis functions and reconstruction algorithms are used to investigate best fitting two dimensional tomographic images of ionosphere electron density in height and latitude for one satellite and one receiver pair. Twodimensional ionospheric tomography over the low. Spie 2027, advanced signal processing algorithms, architectures, and implementations iv. The tec, which is the main input to cit, is defined.
Electronic systems and signals research laboratory department of electrical and systems engineering washington university st. A new ionospheric tomographic algorithm indian academy of. A simple and relatively fast method csart is presented for tomographic reconstruction of the electron density distribution in the ionosphere using smooth fields. A modified threedimensional ionospheric tomography. Tomographic reconstruction of the ionosphere using ground. Algorithms and basis functions in tomographic reconstruction of ionospheric electron density ersin yavuz 1, feza ar.
The necessary data are transionospheric satellite beacon total electron content tec data recorded simultaneously at multiple ground stations. In satellite radio tomography, now commonly referred to as computerized ionospheric tomography cit, total electron content tec measurements are inverted and reconstructed to obtain a twodimensional electron density profile. To test the accuracy of the ionospheric tomography algorithms, a truth ionosphere is needed, with an associated data set of gnss tecmeasurements. Ionospheric tomography algorithms, international journal.
Ionosphere tomography using wavelet neural network and. In the problem of imaging a patient we shone xrays through their body. Since it does not use matrix algebra, it can be implemented in a lowlevel programming language, which speeds up applications significantly. Alternating minimization algorithms for transmission tomography joseph a. Read ionospheric tomography algorithms, international journal of imaging systems and technology on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. A new method of monitoring the ionosphere based on radio tomography can be. A new ionospheric tomographic algorithm constrained multiplicative algebraic reconstruction technique cmart. Therefore, it is very necessary to develop an ionospheric tomography algorithm with high ef. This absolute phase approach to the ray tomography of the ionosphere suffers from the problem of. A hybrid reconstruction algorithm for 3d ionospheric tomography.
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