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Termes IGN > sciences naturelles > sciences de la Terre et de l'univers > géosciences > géographie physique > météorologie > aérologie > atmosphère terrestre > ionosphère > modèle ionosphérique
modèle ionosphériqueSynonyme(s)modèle de propagation ionosphèrique |
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vol 85 n° 12 - December 2011 - Special issue : Ionosphere (Bulletin de Journal of geodesy) / M. Schmidt
[n° ou bulletin]
Titre : vol 85 n° 12 - December 2011 - Special issue : Ionosphere Type de document : Périodique Auteurs : M. Schmidt, Éditeur scientifique ; International association of geodesy, Auteur Année de publication : 2011 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] International Reference Ionosphere
[Termes IGN] ionosphère
[Termes IGN] modèle ionosphériqueAffiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Numéro de périodique En ligne : http://link.springer.com/journal/190/85/12/page/1 Format de la ressource électronique : URL sommaire Permalink : https://documentation.ensg.eu/index.php?lvl=bulletin_display&id=21768 [n° ou bulletin]Contient
- The ionosphere : effects, GPS modeling and the benefits for space geodetic techniques / Manuel Hernández-Pajares in Journal of geodesy, vol 85 n° 12 (December 2011)
- The international reference ionosphere today and in the future / Dieter Bilitza in Journal of geodesy, vol 85 n° 12 (December 2011)
- Validation of international reference ionosphere models using in situ measurements from GRACE K-band ranging system and CHAMP planar Langmuir probe / C. Lee in Journal of geodesy, vol 85 n° 12 (December 2011)
- Combination of different space-geodetic observations for regional ionosphere modeling / D. Dettmering in Journal of geodesy, vol 85 n° 12 (December 2011)
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Code-barres Cote Support Localisation Section Disponibilité 266-2011121 RAB Revue Centre de documentation En réserve L003 Disponible Simulation study of the influence of the ionospheric layer height in the thin layer ionospheric model / C. Brunini in Journal of geodesy, vol 85 n° 9 (September 2011)
[article]
Titre : Simulation study of the influence of the ionospheric layer height in the thin layer ionospheric model Type de document : Article/Communication Auteurs : C. Brunini, Auteur ; E. Camilion, Auteur ; F. Azpilicueta, Auteur Année de publication : 2011 Article en page(s) : pp 637 - 645 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] altitude
[Termes IGN] données GNSS
[Termes IGN] erreur systématique
[Termes IGN] modèle ionosphérique
[Termes IGN] propagation ionosphérique
[Termes IGN] simulation
[Termes IGN] teneur totale en électrons
[Termes IGN] variation saisonnièreRésumé : (Auteur) This work aims to contribute to the understanding of the influence of the ionospheric layer height (ILH) on the thin layer ionospheric model (TLIM) used to retrieve ionospheric information from the GNSS observations. Particular attention is paid to the errors caused on the estimation of the vertical total electron content (vTEC) and the GNSS satellites and receivers inter-frequency biases (IFB), by the use of an inappropriate ILH. The work relies upon numerical simulations performed with an empirical model of the Earth’s ionosphere: the model is used to create realistic but controlled ionospheric scenarios and the errors are evaluated after recovering those scenarios with the TLIM. The error assessment is performed in the Central and the northern part of the South American continents, a region where large errors are expected due to the combined actions of the Appleton Anomaly of the ionosphere and the South-Atlantic anomaly of the geomagnetic field. According to this study, there does not exist a unique ILH that cancels the vTEC error for the whole region under consideration. The ILH that cancels the regional mean vTEC error varies with the solar activity and season. The latitude-dependent conversion error propagates to the parameters of the model used to represent the latitudinal variation on the vTEC on the ionospheric layer, and to the IFB, when these values are simultaneously estimated from the observed sTEC. Besides, the ILH that cancels the regional mean vTEC error is different from the one that cancels the IFB error and the difference between both ILH varies with the solar activity and season. Numéro de notice : A2011-377 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-011-0470-2 Date de publication en ligne : 19/04/2011 En ligne : https://doi.org/10.1007/s00190-011-0470-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31156
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Code-barres Cote Support Localisation Section Disponibilité 266-2011091 RAB Revue Centre de documentation En réserve L003 Disponible Wide-area RTK: high precision positioning on a continental scale / Manuel Hernández-Pajares in Inside GNSS, vol 5 n° 2 (March - April 2010)
[article]
Titre : Wide-area RTK: high precision positioning on a continental scale Type de document : Article/Communication Auteurs : Manuel Hernández-Pajares, Auteur ; et al., Auteur Année de publication : 2010 Article en page(s) : 12 p. ; pp 35 - 46 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] atmosphère terrestre
[Termes IGN] correction du signal
[Termes IGN] modèle ionosphérique
[Termes IGN] positionnement cinématique en temps réel
[Termes IGN] propagation ionosphérique
[Termes IGN] récepteur GNSS
[Termes IGN] traitement de données GNSSRésumé : (Auteur) Real-time corrections at the decimeter level over an entire continent? The challenge lies in minimizing the ranging errors from signals propagating through the Earth’s atmosphere. European researchers describe how it can be done using a Wide Area Real-Time Kinematic concept that exploits the full geometry of the observations, a central processing facility, and undifferenced processing of measurements from widely space GNSS reference receivers to create a real-time ionospheric model of the signal slant delays. Copyright Gibbons Media & Research LLC Numéro de notice : A2010-619 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=33569
in Inside GNSS > vol 5 n° 2 (March - April 2010) . - 12 p. ; pp 35 - 46[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 159-2010021 SL Revue Centre de documentation Revues en salle Disponible Documents numériques
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Wide-area RTK ... - pdf éditeurAdobe Acrobat PDF Ionospheric modeling for precise GNSS applications / Y. Memarzadeh (2009)
Titre : Ionospheric modeling for precise GNSS applications Type de document : Monographie Auteurs : Y. Memarzadeh, Auteur Editeur : Delft : Netherlands Geodetic Commission NGC Année de publication : 2009 Collection : Netherlands Geodetic Commission Publications on Geodesy, ISSN 0165-1706 num. 71 Importance : 208 p. Format : 17 x 24 cm ISBN/ISSN/EAN : 978-90-6132-314-3 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] antenne GNSS
[Termes IGN] correction ionosphérique
[Termes IGN] double différence
[Termes IGN] modèle ionosphérique
[Termes IGN] positionnement différentiel
[Termes IGN] positionnement par GNSS
[Termes IGN] précision centimétrique
[Termes IGN] propagation du signal
[Termes IGN] propagation ionosphérique
[Termes IGN] simple différence
[Termes IGN] temps réel
[Termes IGN] teneur totale en électrons
[Termes IGN] traitement de données GNSSIndex. décimale : 30.61 Systèmes de Positionnement par Satellites du GNSS Résumé : (Auteur) The main objective of this thesis is to develop a procedure for modeling and predicting ionospheric Total Electron Content (TEC) for high precision differential GNSS applications. As the ionosphere is a highly dynamic medium, we believe that to have a reliable procedure it is necessary to transfer the high temporal resolution GNSS network data into the spatial domain. This objective led to the development of a recursive physics-based model for the regular TEC variations and an algorithm for real-time modeling of the medium-scale Traveling Ionospheric Disturbances (MS-TID). The research described in this thesis can roughly be divided into three parts.
The main application of these developments can be found in Network RTK. Network-RTK is a technique based on a network of reference receivers to provide cm-level positioning accuracy in real time for users in the field. To get centimeter accuracy after a short (minutes) initialization period the ionospheric delay for the user's receiver needs to be predicted very precisely between the ionospheric pierce points of the reference receivers at the double difference level. Having the cm-level accuracy in the ionospheric interpolation is crucial for the carrier phase ambiguity resolution by the user. To achieve high precision in the ionospheric interpolation, regular and irregular variability of TEC in time and space should be taken into account. The regular TEC variation, which can reach several hundreds TEC units, is mainly a function of solar zenith angle. The irregular (or non-repeatable) variations are mainly wavelike effects associated with Traveling Ionospheric Disturbances (TID).
Although TID effects on the TEC are of the order of 0.1 TEC unit, MS-TIDs, with a typical wavelength less than a few hundred kilometers, is one of the main obstacles for accurate spatial interpolation of ionospheric induced delays in a medium-scale reference GPS network. Since most of interpolation methods either use spatial linear (or quadratic) interpolation or fit a lower-order surface, the methods are not capable to model the phase-offset, caused by MS-TIDs, at distinct ionospheric pierce points. There are two major complications. Firstly, interpolation must be done at the double-difference level, which involves taking single differences between ionospheric delays for the same satellite between two different receivers, followed by differencing single differences for different satellites. This means that two different patches of the ionosphere are involved, each related to a different satellite, and each possibly associated with different TIDs. Secondly, for operational network RTK, a real-time strategy for TID detection and modeling is needed.
In the first part the performance of several empirical ionosphere models for the regular TEC variation, such as Klobuchar, NeQuick, and the IGS Global Ionosphere Maps (GIM) are studied in the mid-latitude region using GPS data. Our results show that the GIM was able to correct the absolute slant ionospheric delay to better than 80% under different geomagnetic conditions of the ionosphere. The NeQuick model, which performed better than the Klobuchar model, could correct about 60% of the slant ionospheric delay. NeQuick is a real-time ionospheric correction model for the future European Galileo navigation system. A key input parameter for NeQuick is the effective ionization parameter (Az), which will be provided as a second order polynomial in the Galileo broadcast message to single-frequency users. The coefficients of the polynomial will be estimated daily from at least 20 permanent Galileo monitoring stations. As Galileo is under development, we propose an alternative approach for estimating Az using Global Ionospheric Maps (GIM). The main advantages of the alternative approach over the standard approach are: (1) the alternative approach is more reliable, because, each IGS GIM is based on data of up to 300 GNSS stations world-wide and each IGS GIM is the combination of results of up to four analysis centers, (2) the coefficients are more representative for all regions on the world because they are computed from a world-wide grid instead of about 20 distinct locations, (3) with the alternative procedure it is possible to provide Az in a different representation, for instance using a higher order polynomial, grid, or other function types, and (4) the computational effort is much smaller assuming the IGS GIMs have already been computed.
In the second part a normal ionosphere is defined using Chapman's ion production theory to approximate the regular variability of the Earth's ionosphere. The normal ionosphere consists of lower and upper region. The lower region is formed in a photochemical equilibrium resulting in a Chapman layer. The upper region is formed in a diffusive equilibrium, whilst ignoring the geomagnetic field, resulting in a new Chapman like ionospheric layer. Integration of the continuity equation of the normal ionosphere over height leads to a Boundary Value Problem (BVP) for the temporal evolution of VTEC. Solution of the BVP results in a novel recursive model for the regular TEC variation as a function of solar zenith angle. The main motivation for developing this model is that the empirical models of the first part were either ill-suited or too complicated to model and predict the regular variation of TEC for high precision differential GNSS applications. The performance of the new model is tested at local and global scales using GIM. In general, despite the geomagnetic field was ignored, the cases analyzed show that the model gives a good overall representation of the regular variation of VTEC in the mid-latitude region under a geomagnetically quiet ionosphere. This is an important result that shows the potential of the model for a number of applications. Since the model has a recursive form it is ideally suited to use as time update equation in a dynamic data processing or Kalman filter. Another application is to use it for removing the geometry-dependent trend from time series of GPS-provided ionospheric delays to provide a pure TID observation, which is carried out in the third part of this thesis.
In the third part, a new algorithm for the real-time detection and modeling of MS-TID effects is developed. In order to eliminate effects from large-scale TIDs, the algorithm uses between-receiver single-difference (SD) ionospheric delays in a medium scale GPS network. Although single-differencing also eliminates to some extend the geometry-dependent trend, the remaining part cannot be neglected. In this thesis, we fit the SD data to the recursive model which was developed in the second part of the thesis. Any wavelike fluctuations in the data with respect to the model are assumed to be from MS-TID effects. The detrended SD data are the main input of the algorithm. The algorithm consists of six steps: initialization, detection, scraping, cross-correlation, parameter estimation, and ending. A MS-TID is assumed to be a planar longitudinal traveling wave with spatially independent amplitude that propagates in an ionospheric patch. All characteristic parameters of the MS-TID wave (e.g. period, phase velocity, propagation direction, and amplitude) are considered to be time dependent, while the Doppler-shift caused by the satellite motion is taken into account in the estimation step. The performance of the algorithm is tested with GPS data from a network. Although real TIDs are not perfect waves, the algorithm was able to model (in time and in space) the MS-TID to a large extend. The performance was found to be comparable with the Kriging interpolation method. This is an important first result, in part because these two methods are based on different principles, but also because there is still room for improvement in our algorithm. With our physics based model it is possible to avoid the planar wave approximation and take the phase-offset of the wave into account, something which is not possible with Kriging.Note de contenu : Curriculum Vitae Acknowledgments Notation and Symbols Acronyms
1 Introduction
1.1 Background
1.2 Research objectives
1.3 Outline of the thesis
1.4 Contributions of this research
2 The Earth's Atmosphere, Sun, and Geomagnetism
2.1 The Earth's Atmosphere .
2.1.1 Pressure, temperature and density variations
2.1.2 Diffusive equilibrium
2.1.3 Upper atmosphere .
2.2 The Sun
2.2.1 The Solar radiation
2.2.2 Variation of the radiation intensity
2.2.3 Solar radiations index (F10.7) .
2.3 Geomagnetism .
2.3.1 The earth's magnetic dipole field
2.3.2 The real geomagnetic field
2.3.3 Geomagnetic storm
2.3.4 Geomagnetic indices
3 Physics of the Earth's Ionosphere
3.1 Interaction of solar radiation with the Earth's upper atmosphere
3.2 Ionosphere formation theory
3.2.1 Plasma continuity equation
3.2.2 Ion production
3.2.3 Ion and electron disappearance .
3.2.4 Chapman layer
3.3 Transport process in the ionosphere .
3.3.1 Charged particle motion in a magnetic field .
3.3.2 Plasma diffusion .
3.3.3 Thermospheric wind .
3.3.4 Electromagnetic drift
3.4 Ionospheric stratification .
3.4.1 The D-Region
3.4.2 The E-Region
3.4.3 The F-Region
3.4.4 The topside region and the protonosphere .
3.4.5 Vertical electron density profile of the ionosphere
3.4.6 Characteristic parameters of the ionospheric regions
3.5 Spatial and temporal variability of the ionosphere
3.5.1 Regular variations
3.5.2 Geomagnetic regions .
3.6 Solar disturbances
3.6.1 Ionospheric disturbances .
3.6.2 Atmospheric gravity waves
3.6.3 Traveling ionospheric disturbances
4 Ionospheric delay measured from GNSS
4.1 Global Navigation Satellite Systems (GNSS) .
4.2 GNSS observation equations
4.2.1 Code or pseudo-range observation equation
4.2.2 Carrier beat phase observation equation
4.2.3 Simplifications of the observation equations
4.2.4 Tropospheric effects
4.3 Ionospheric propagation of GNSS signals .
4.3.1 Inhomogeneity of the ionosphere .
4.3.2 Dispersivity of the ionosphere .
4.3.3 Anisotropy of the ionosphere .
4.3.4 Ionospheric refractive index
4.3.5 Ionospheric first-, higher-order and bending effects . .
4.4 Ionospheric Total Electron Content (TEC)
4.4.1 A single-layer ionosphere approximation
4.4.2 Approximation of the higher-order and bending effects
4.5 Ionospheric models
4.5.1 Klobuchar model
4.5.2 Global Ionosphere Maps
4.6 Slant ionospheric delay measurements from GNSS
4.6.1 Network processing
4.6.2 Geometry-free linear combination 4.7 Summary
5 NeQuick 3D Ionospheric Electron Density Profiler
5.1 Ionospheric electron density model NeQuick
5.1.1 NeQuick model formulation for the bottom side (h < hmaXtF2)
5.1.2 NeQuick model formulation for the top side (hmax,F2 < /')
5.2 Characteristic parameters of the anchor points
5.2.1 Peak height of the F'2 region
5.2.2 Thickness parameters of the semi-Epstein layers
5.3 Providing the ionosonde parameters for NeQuick .
5.3.1 CCIR maps of /0F2 and M(3000)F2
5.3.2 Diagrammatic presentation of NeQuick
5.4 NeQuick for the Galileo navigation system
5.4.1 Effective Ionization Level (Az parameter) .
5.4.2 Estimation of the effective ionization level (nominal approach)
5.4.3 Improved version of NeQuick .
5.5 Estimation of the effective ionization level using GIM .
5.5.1 Estimation of the effective ionization level (alternative approach
5.5.2 Daily grid-based map of the effective ionization level
5.5.3 Az parameter for single point positioning .
5.6 Validation of the alternative approach .
5.6.1 Consistency of the approaches .
5.6.2 Modeling the spatial dependency of the Az parameter
5.6.3 Correlation between Az and F10.7
5.7 Performance of the NeQuick ionospheric model
5.7.1 Data specifications and processing
5.7.2 Comparison between the model errors .
5.8 Concluding remarks ..
6 Physics-Based Modeling of TEC
6.1 Normal ionosphere
6.1.1 Vertical electron density profile in the normal ionosphere . . . .
6.1.2 VTEC in the normal E-region .
6.1.3 VTEC in the normal F-region .
6.1.4 Combined VTEC of the normal ionosphere
6.1.5 Slant TEC in the normal ionosphere
6.2 Recursive model of VTEC in the normal ionosphere
6.2.1 Parametrization of the VTEC model .
6.2.2 Providing the model parameters
6.2.3 Functional model for estimating the parameters
6.2.4 Linearization of the functional model .
6.2.5 Least-squares solution of the model parameters
6.3 Performance of the VTEC model .
6.3.1 Local test of the VTEC model .
6.3.2 Global test of the VTEC model .
6.3.3 Applications of the VTEC model 6.4 Summary
7 Real-Time Modeling for Medium-Scale TID
7.1 Introduction
7.2 Medium-Scale Traveling Ionospheric Disturbances
7.3 Mechanical longitudinal wave equation
7.3.1 Traveling plane wave
7.3.2 Standing plane wave
7.4 GPS-provided TID observation .
7.4.1 Geometry-dependent trend of slant ionospheric delay
7.4.2 TID observation
7.4.3 Single-difference TID observation .
7.4.4 Double-difference TID observation .
7.5 TID observation equation .
7.5.1 Doppler-shift on TID observation .
7.6 Estimation of TID wave parameters
7.6.1 Period determination
7.6.2 TID wave vector determination
7.6.3 TID wave amplitude determination
7.7 Real-Time Medium-scale TID modeling
7.7.1 Initialization step
7.7.2 TID detection and scraping steps .
7.7.3 Cross correlation step .
7.7.4 TID parameter estimation .
7.7.5 TID ending .
7.7.6 Flowchart of the Real-Time TID modeling algorithm
7.7.7 Dependency on reference baseline .
7.7.8 Sensitivity to temporal resolution .
7.8 Implementation of the Real-Time TID modeling .
7.8.1 Case study: PRN 02
7.8.2 Case study: PRN 08
7.9 Conclusions and remarks
8 Conclusions and recommendations
8.1 Estimation of effective ionization for NeQuick .
8.2 Spatial and temporal variation of effective ionization level .
8.3 Performance of global TEC models
8.4 Model of temporal evolution of VTEC .
8.5 Modeling Medium-Scale Traveling Ionospheric Disturbances
Bibliography
IndexNuméro de notice : 15510 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Monographie Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=62743 Réservation
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Code-barres Cote Support Localisation Section Disponibilité 15510-01 30.61 Livre Centre de documentation Géodésie Disponible Ionospheric modeling: the key to GNSS ambiguity resolution / T. Richert in GPS world, vol 16 n° 6 (June 2005)
[article]
Titre : Ionospheric modeling: the key to GNSS ambiguity resolution Type de document : Article/Communication Auteurs : T. Richert, Auteur ; Naser El-Sheimy, Auteur Année de publication : 2005 Article en page(s) : pp 35 - 40 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] ambiguïté entière
[Termes IGN] diffusion du rayonnement
[Termes IGN] Global Navigation Satellite System
[Termes IGN] modèle ionosphérique
[Termes IGN] précision des données
[Termes IGN] précision géométrique (imagerie)
[Termes IGN] propagation ionosphérique
[Termes IGN] résolution d'ambiguïtéRésumé : (Editeur) The GPS carrier-phase observable is more than 100 times more precise than the code-based pseudorange observable. Unfortunatly, it is also ambigous. If we want to use the carrier phase as a range measurement in positioning or navigation, we must account somehow for the unknown integer number of cycles or turns of phase in the initial measurement when a GPS receiver locks onto satellite's L1 or L2 signal carrier. Mathematicians, scientists and engineering have developed clever techniques for helping these integer ambiguities either in real time or in post-processing collected data. However, the success of these techniques in correctly determining the ambiguities depends on several factors including wether a point or relative positioning technique is employed, the length of the baseline in relative positioning, and how well a variety of errors afflicting the measurements can be mitigated. One source of such errors is the ionosphere. In this month's column, we examine how ionospheric modeling helps in the resolution of carrier-phase ambiguities and how the rate of success in correctly determining the ambiguities will be much improved when GPS observations are combined with those of the future Gallileo system. Numéro de notice : A2005-279 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=27415
in GPS world > vol 16 n° 6 (June 2005) . - pp 35 - 40[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 067-05061 SL Revue Centre de documentation Revues en salle Disponible L'utilisation du GPS pour l'imagerie de l'ionosphère / J. Artru in Géochronique, n° 94 (juin - août 2005)PermalinkIonosphere modelling using carrier smoothed ionosphere observations from a regional GPS network / Yang Gao in Geomatica, vol 56 n° 2 (June 2002)PermalinkFast precise GPS positioning in the presence of ionospheric delays / Dennis Odijk (2002)PermalinkReal-time estimation of ionospheric delay using GPS measurements / L.S. Lin (1998)PermalinkEvaluation du nouveau modèle du Bernese software / Serge Botton in Bulletin d'information de l'Institut géographique national, n° 68 (octobre 1997)PermalinkEtude du comportement du contenu électronique total et de ses irrégularités dans une région de latitude moyenne / René Warnant (1996)PermalinkA recursive procedure for computation and quality control of GPS differential corrections / X. Jin (1995)PermalinkPermalinkModeling the ionosphere for an active control network of GPS stations / Y. Georgiadiou (1993)PermalinkProceedings of the symposium refraction of transatmospheric signals in geodesy / J.C. DE Munck (1992)Permalink