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Titre : Water vapor tomography using global navigation satellites systems Type de document : Thèse/HDR Auteurs : Donat Perler, Auteur Editeur : Zurich : Schweizerischen Geodatischen Kommission / Commission Géodésique Suisse Année de publication : 2012 Collection : Geodätisch-Geophysikalische Arbeiten in der Schweiz, ISSN 0257-1722 num. 84 Importance : 188 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-908440-30-7 Note générale : Bibliographie
Doctoral ThesisLangues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] atmosphère terrestre
[Termes IGN] données GNSS
[Termes IGN] données météorologiques
[Termes IGN] modélisation spatiale
[Termes IGN] positionnement par GNSS
[Termes IGN] rayonnement électromagnétique
[Termes IGN] temps réel
[Termes IGN] teneur en vapeur d'eau
[Termes IGN] tomographie par GPS
[Termes IGN] vapeur d'eauIndex. décimale : 30.84 Applications de géodésie spatiale à l'atmosphère Résumé : (Auteur) Water vapor plays an important role in the atmosphere. It is involved in many atmospheric processes and is a major contributor to the atmospheric energy budget and as such is a key quantity in numerical weather prediction (NWP) models. In recent years, NWP models gain in importance in hazard mitigation. But to provide precise quantitative forecasts, especially with respect to precipitation, we need accurate knowledge of the water vapor distribution in the atmosphere. Ground-based Global Navigation Satellite System (GNSS) tomography is a technique which can provide highly resolved and accurate water vapor profiles in space and time.
The main objective of this thesis is to develop new tomographic algorithms which fulfill the requirements to assimilate refractivity measurements derived from GNSS into NWP models. A new tomography software called AWATOS 2 has been implemented. It is an assimilation system for point and integrated refractivity measurements. The tomographic model in AWATOS 2 is formulated as a Kalman filter and different voxel parameterizations are provided. The new trilinear and spline-based parameterizations allow a more accurate representation of the refractivity field without considerably increasing the number of unknowns. Advantages of these new parameterizations are a) more accurate results, b) point observations need not to be interpolated to the voxel centers and c) the tomographic solutions are at least C0-continuous in space. The stochastic prediction model implemented in AWATOS 2 relies on in-situ measurements and NWP model data. The prediction model is evaluated and adjusted with respect to data from the high-resolution NWP model COSMO-2 and from balloon soundings in Europe. In addition, AWATOS 2 provides a sophisticated simulation framework to carry out synthetic tests based on simple refractivity fields and on NWP model data. The algorithms of AWATOS 2 are assessed with synthetic tests and with real data in a longterm study using one year of data. The synthetic tests have confirmed the theoretical properties of the model such as a bias-free solution in case of bias-free input data, fast convergence rates, and the capability to resolve vertical structures in the wet refractivity field. In the long-term study, a root-mean-square (RMS) error of 3.0 ppm (0.4 gm3 absolute humidity) is achieved with respect to the NWP model COSMO-7. The investigations have shown that the newly introduced voxel parameterizations lead to significantly more accurate results than the classical constant parameterization.
The improvements are about 15% with respect to balloon soundings and 5% with respect to NWP analysis data. The performance of the trilinear and spline-based parameterizations are similar. Further investigations have revealed the importance of a bias correction model. A newly developed bias correction model has decreased the RMS error with respect to the NWP model analysis from 4.9 ppm (0.7 gm3) to 3.0 ppm (0.4 gm3) using the spline parameterization. For the other parameterizations, the improvements are significantly smaller. The systematic differences corrected here are mainly caused by a) systematic differences between GPS tropospheric path delays and the NWP model data and b) by discretization errors. Another error source is related to the departure of the NWP model’s topography from the true one which can amount to several hundred meters in alpine areas. Investigations have shown that processes near the Earth’s surface have a strong impact on the wet refractivity. Therefore, differences between the true topography and that of the NWP model can cause substantial errors. This topic has to be addressed if GNSS observations are assimilated into NWP models in complex terrain. Considerable progress has been made in the field of low-cost GNSS receivers in recent years allowing to build dense networks at low costs. Furthermore, the existing GNSSs are improved and new ones are being launched. These developments offer new possibilities in GNSS tomography. With error analyses, the potential of such improvements for GNSS tomography have been investigated The use of GPS together with Galileo has the potential to improve the formal accuracy of the GNSS tomography by 10-15% compared to a GPS-only solution. In Switzerland, equipping the SwissMetNet with GNSS receivers would increase the number of GNSS stations from 31 to 91. This would improve the formal accuracy of the tomographic solution by about 20-25%. The investigations have shown that the improvements obtained by a more dense network and additional GNSSs are cumulative. Placing the stations on different altitudes and choosing locations with good satellite visibility are important to achieve accurate results and should be considered in the design of GNSS networks.
All investigations have demonstrated that accurate 4D distributions of the wet refractivity in the troposphere can be estimated with GNSS tomography. The work has also revealed the possibilities and limitations of GNSS tomography in view of the assimilation into NWP models and proposes solution strategies to overcome the limitations.Note de contenu : 1 Introduction
1.1 Significance of tropospheric water vapor measurements
1.2 A short review of the research in GNSS tomography
1.3 Objectives and structure of the thesis
2 Introduction to the propagation of radio waves in the atmosphere
2.1 Propagation of radio waves in the atmosphere
2.2 Modeling the path delay
3 GNSS tomography with the software package AWATOS 2
3.1 Overview of AWATOS 2
3.2 Preprocessing of GNSS double difference delays
3.3 Discretization of the refractivity field and parameterization
3.4 Modeling the refractivity field with the Kalman filter approach
3.5 Simulation capabilities in AWATOS 2
4 Overview of the data sets
4.1 GPS data
4.2 Balloon soundings
4.3 Synoptic network SwissMetNet
4.4 Numerical weather prediction model COSMO
5 Description of the wet refractivity field
5.1 Tempo-spatial variation of the wet refractivity field
5.2 Discretization Error
5.3 Representation of the discretization error .
5.4 Investigations of the process noise using a random walk model
5.5 Conclusions
6 Comparison of balloon sounding data and GNSS-derived zenith path delays
6.1 Error budget of meteorological sensors
6.2 Intercomparison between zenith path delays of different sources
6.3 Conclusions
7 Potential of new GNSSs and dense networks in view of GNSS tomography
7.1 Configurations
7.2 Methods
7.3 Results and discussion
7.4 Conclusions
8 Simulation-based evaluation of the new tomographic algorithms
8.1 Theoretical considerations of the resolvability of vertical structures
8.2 Experiments with simulated data
8.3 Conclusions
9 Evaluation of the GPS tomography with a long-term study
9.1 Configuration and evaluation methods
9.2 Results and discussion
9.3 Bias correction model and its evaluation
9.4 Conclusions
10 Conclusions
11 OutlookNuméro de notice : 15546 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse étrangère DOI : 10.3929/ethz-a-006875504 En ligne : http://dx.doi.org/10.3929/ethz-a-006875504 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=62758 Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 15546-01 30.84 Livre Centre de documentation Géodésie Disponible Combination of different space-geodetic observations for regional ionosphere modeling / D. Dettmering in Journal of geodesy, vol 85 n° 12 (December 2011)
[article]
Titre : Combination of different space-geodetic observations for regional ionosphere modeling Type de document : Article/Communication Auteurs : D. Dettmering, Auteur ; M. Schmidt, Auteur ; Robert Heinkelmann, Auteur ; Manuela Seitz, Auteur Année de publication : 2011 Article en page(s) : pp 989 - 998 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] analyse combinatoire (maths)
[Termes IGN] B-Spline
[Termes IGN] correction ionosphérique
[Termes IGN] ionosphère
[Termes IGN] modèle ionosphérique
[Termes IGN] teneur totale en électronsRésumé : (Auteur) Most of the space-geodetic observation techniques can be used for modeling the distribution of free electrons in the Earth’s ionosphere. By combining different techniques one can take advantage of their different spatial and temporal distributions as well as their different observation characteristics and sensitivities concerning ionospheric parameter estimation. The present publication introduces a procedure for multi-dimensional ionospheric modeling. The model consists of a given reference part and an unknown correction part expanded in terms of B-spline functions. This approach is used to compute regional models of Vertical Total Electron Content (VTEC) based on the International Reference Ionosphere (IRI 2007) and GPS observations from terrestrial Global Navigation Satellite System (GNSS) reference stations, radio occultation data from Low Earth Orbiters (LEOs), dual-frequency radar altimetry measurements, and data obtained by Very Long Baseline Interferometry (VLBI). The approach overcomes deficiencies in the climatological IRI model and reaches the same level of accuracy than GNSS-based VTEC maps from IGS. In areas without GNSS observations (e.g., over the oceans) radio occultations and altimetry provide valuable measurements and further improve the VTEC maps. Moreover, the approach supplies information on the offsets between different observation techniques as well as on their different sensitivity for ionosphere modeling. Altogether, the present procedure helps to derive improved ionospheric corrections (e.g., for one-frequency radar altimeters) and at the same time it improves our knowledge on the Earth’s ionosphere. Numéro de notice : A2011-504 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-010-0423-1 Date de publication en ligne : 10/11/2011 En ligne : https://doi.org/10.1007/s00190-010-0423-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31398
in Journal of geodesy > vol 85 n° 12 (December 2011) . - pp 989 - 998[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 266-2011121 RAB Revue Centre de documentation En réserve L003 Disponible 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)
Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 266-2011121 RAB Revue Centre de documentation En réserve L003 Disponible The international reference ionosphere today and in the future / Dieter Bilitza in Journal of geodesy, vol 85 n° 12 (December 2011)
[article]
Titre : The international reference ionosphere today and in the future Type de document : Article/Communication Auteurs : Dieter Bilitza, Auteur ; L. Mckinnel, Auteur ; Bodo Reinisch, Auteur ; T. Fuller-Rowell, Auteur Année de publication : 2011 Article en page(s) : pp 909 - 920 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] International Reference Ionosphere
[Termes IGN] ionosphère
[Termes IGN] modèle empirique
[Termes IGN] modèle ionosphérique
[Termes IGN] teneur totale en électronsRésumé : (Auteur) The international reference ionosphere (IRI) is the internationally recognized and recommended standard for the specification of plasma parameters in Earth’s ionosphere. It describes monthly averages of electron density, electron temperature, ion temperature, ion composition, and several additional parameters in the altitude range from 60 to 1,500 km. A joint working group of the Committee on Space Research (COSPAR) and the International Union of Radio Science (URSI) is in charge of developing and improving the IRI model. As requested by COSPAR and URSI, IRI is an empirical model being based on most of the available and reliable data sources for the ionospheric plasma. The paper describes the latest version of the model and reviews efforts towards future improvements, including the development of new global models for the F2 peak density and height, and a new approach to describe the electron density in the topside and plasmasphere. Our emphasis will be on the electron density because it is the IRI parameter most relevant to geodetic techniques and studies. Annual IRI meetings are the main venue for the discussion of IRI activities, future improvements, and additions to the model. A new special IRI task force activity is focusing on the development of a real-time IRI (RT-IRI) by combining data assimilation techniques with the IRI model. A first RT-IRI task force meeting was held in 2009 in Colorado Springs. We will review the outcome of this meeting and the plans for the future. The IRI homepage is at http://www.IRI.gsfc.nasa.gov. Numéro de notice : A2011-502 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-010-0427-x Date de publication en ligne : 10/11/2011 En ligne : https://doi.org/10.1007/s00190-010-0427-x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31396
in Journal of geodesy > vol 85 n° 12 (December 2011) . - pp 909 - 920[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 266-2011121 RAB Revue Centre de documentation En réserve L003 Disponible 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)
[article]
Titre : The ionosphere : effects, GPS modeling and the benefits for space geodetic techniques Type de document : Article/Communication Auteurs : Manuel Hernández-Pajares, Auteur ; M. Juan, Auteur ; Jaume Sanz, Auteur ; et al., Auteur Année de publication : 2011 Article en page(s) : pp 887 - 907 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] données GNSS
[Termes IGN] données GPS
[Termes IGN] ionosphère
[Termes IGN] modèle ionosphérique
[Termes IGN] perturbation ionosphérique
[Termes IGN] propagation du signal
[Termes IGN] qualité du signal
[Termes IGN] signal GNSS
[Termes IGN] signal GPS
[Termes IGN] surveillance
[Termes IGN] teneur totale en électronsRésumé : (Auteur) The main goal of this paper is to provide a summary of our current knowledge of the ionosphere as it relates to space geodetic techniques, especially the most informative technology, global navigation satellite systems (GNSS), specifically the fully deployed and operational global positioning system (GPS). As such, the main relevant modeling points are discussed, and the corresponding results of ionospheric monitoring are related, which were mostly computed using GPS data and based on the direct experience of the authors. We address various phenomena such as horizontal and vertical ionospheric morphology in quiet conditions, traveling ionospheric disturbances, solar flares, ionospheric storms and scintillation. Finally, we also tackle the question of how improved knowledge of ionospheric conditions, especially in terms of an accurate understanding of the distribution of free electrons, can improve space geodetic techniques at different levels, such as higher-order ionospheric effects, precise GNSS navigation, single-antenna GNSS orientation and real-time GNSS meteorology. Numéro de notice : A2011-501 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-011-0508-5 Date de publication en ligne : 11/09/2011 En ligne : https://doi.org/10.1007/s00190-011-0508-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31395
in Journal of geodesy > vol 85 n° 12 (December 2011) . - pp 887 - 907[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 266-2011121 RAB Revue Centre de documentation En réserve L003 Disponible 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)PermalinkAccuracy assessment of the GPS-TEC calibration constants by means of a simulation technique / Jacques Conte in Journal of geodesy, vol 85 n° 10 (October 2011)PermalinkSimulation 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)PermalinkThe right attitude: Experimenting with GPS on board high-altitude balloons / P. Buist in GPS world, vol 22 n° 9 (September 2011)PermalinkPermalink4D GPS water vapor tomography: new parameterized approaches / Donat Perler in Journal of geodesy, vol 85 n° 8 (August 2011)Permalinkvol 85 n° 7 - July 2011 - CONT08 -continuous geodetic VLBI campaign 2008 August 12-26 2008 (Bulletin de Journal of geodesy) / Axel NothnagelPermalinkMulti-technique comparison of troposphere zenith delays and gradients during CONT08 / Kamil Teke in Journal of geodesy, vol 85 n° 7 (July 2011)Permalinkvol 99 n° 2 - 01/04/2011 - Austrian contribution to the XXV [25] general assembly of the International union of geodesy and geophysics (IUGG), [actes], June 27 - July 8, 2011, Melbourne, Australia (Bulletin de VGI, Österreichische Zeitschrift für Vermessung & GeoInformation) / Österreichische Gesellschaft für Vermessung und Geoinformation (Autriche)PermalinkGNSS and the Ionosphere: What's in Store for the Next Solar Maximum? / A. Jensen in GPS world, vol 22 n° 2 (February 2011)Permalink