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Journal articles on the topic "ITRF00"
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Lestari, Dwi, and Bondan Galih Dewanto. "Analisis Pergeseran Titik Jaring Pemantau Candi Borobudur Mengacu ke ITRF 2008 Berdasarkan Data Pengamatan GPS pada Tahun 2003 dan 2012." JGISE: Journal of Geospatial Information Science and Engineering 3, no. 2 (November 25, 2020): 133. http://dx.doi.org/10.22146/jgise.60451.
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Pemantauan posisi Candi Borobudur bertujuan untuk menjaga warisan dunia. Salah satu caranya adalah dengan pembangunan bench mark (BM) atau titik kontrol untuk pemantauan deformasi menggunakan Global Positioning System (GPS). Pengukuran menggunakan teknologi GPS untuk pemantauan stabilitas Candi Borobudur telah dilakukan pada tahun 2002, 2003, dan 2012, menggunakan Global Kalman Filter VLBI dan analisis GPS dan mengacu pada ITRF2000 untuk menganalisis pergeseran horisontal. ITRF menuntut pemutakhiran data koordinat titik-titik kontrol secara periodik. Perbedaan penggunaan versi ITRF pada pengolahan data GPS berdampak pada perbedaan ketelitian estimasi posisi, besar kecepatan dan arah pergeseran titik-titik kontrol. Tujuan dari penelitian ini adalah untuk mengukur estimasi posisi, kecepatan, dan arah pergerakan dari titik control GPS berdasarkan data 2003 dan 2012 dan mengacu pada ITRF2008. Masing-masing kala melalui tahapan regional processing dan local processing. Koordinat dari hasil local processing GAMIT/GLOBK selanjutnya dibandingkan dengan koordinat hasil olahan mengacu ITRF2000 yang telah ditransformasi menjadi koordinat mengacu ITRF2008. Analisis pergeseran titik berdasarkan koordinat dan hasil dari data 2003 dan 2012. Penelitian ini menghasilkan bahwa perbedaan posisi dan akurasi pada pengolahan regional dan lokal mengindikasikan transformasi dari ITRF2000 ke ITRF2008 berada pada standar deviasi yang dihasilkan GAMIT dan GLOBK yang mengacu pada ITRF2008. Selanjutnya, rata-rata nilai pergeseran horisontal periode 2003 dan 2012 adalah 261 mm arah tenggara (SE) yang serupa dengan penggunaan ITRF2000 pada penelitian sebelumnya. Secara umum, perataan jaring Candi Borobudur yang mengacu pada ITRF 2008 lebih akurat dibandingkan penelitian sebelumnya yang mengacu pada ITRF2000.
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Carvalho, Alessandro Salles, William Rodrigo Dal Poz, and Ana Paula Camargo Larocca. "COMPATIBILIZAÇÃO DE REFERENCIAIS DE COORDENADAS E VELOCIDADES COM ESTIMATIVA DE PRECISÃO." Boletim de Ciências Geodésicas 21, no. 3 (September 2015): 590–609. http://dx.doi.org/10.1590/s1982-21702015000300033.
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Resumo:As transformações de coordenadas e velocidades entre as realizações do ITRS (International Terrestrial Reference System), bem como a atualização de coordenadas, tornar-se-ão tarefas rotineiras em levantamentos geodésicos devido ao emprego de sistemas de referência dinâmicos e ao movimento das placas tectônicas. Neste estudo foram realizadas compatibilizações de sistemas de referência (ITRF2000, ITRF2005 e ITRF2008) das coordenadas e velocidades com suas respectivas estimativas de precisão, via propagação de variância, de 11 estações distribuídas nas placas tectônicas Norte e Sul Americanas e da Eurásia. Foi verificado com base nas coordenadas nos ITRF2008, época 2005 e ITRF2005, época 2000, obtidas pelo IERS (International Earth Rotation and Reference System Service), que 54,55% das discrepâncias planimétricas são centimétricas e 45,45% decimétricas. Comparando as coordenadas no ITRF2008, época 2005,0 e no ITRF2000, época 1997,0 verificou-se discrepâncias planimétricas da ordem do decímetro para todas as estações. Confrontando as coordenadas ITRF2000, época 1997,0 obtidas pelo IERS com as calculadas com base nas transformações entre sistemas de referência e atualizações verifica-se discrepâncias planimétricas da ordem do milímetro em 72,73% dos casos e da ordem do centímetro em 27,27%. As análises realizadas confirmam a necessidade de atualizar e compatibilizar o referencial das coordenadas e velocidades para aumentar a acurácia do posicionamento
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Chujkova, N. A., T. G. Maximova, T. S. Chesnokova, and A. N. Grushinsky. "Earth crust vertical movements according to ITRF2000, ITRF2005, ITRF2008 and ITRF2014 coordinate systems and their comparing analysis." Geodesy and Geodynamics 9, no. 2 (March 2018): 109–14. http://dx.doi.org/10.1016/j.geog.2017.07.007.
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John Robinson P. "Multiple Attribute Group Decision Analysis for Intuitionistic Triangular and Trapezoidal Fuzzy Numbers." International Journal of Fuzzy System Applications 5, no. 3 (July 2016): 42–76. http://dx.doi.org/10.4018/ijfsa.2016070104.
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Solving Multiple Attribute Group Decision Making (MAGDM) problems has become one of the most important researches in recent days. In situations where the information or the data is of the form of an Intuitionistic Triangular Fuzzy Number (ITrFN) or Intuitionistic Trapezoidal Fuzzy Number (ITzFN), a new distance function is defined for ranking the alternatives in the decision making process. After processing the decision information through a sequence of arithmetic aggregation operators, namely, the Intuitionistic Triangular Fuzzy Weighted Arithmetic Averaging (ITrFWAA), Intuitionistic Triangular Fuzzy Ordered Weighted Averaging (ITrFOWA) operator and the Intuitionistic Triangular Fuzzy Hybrid Aggregation (ITrFHA) operator, the proposed distance function is utilized to rank the best alternative. A model is proposed to solve MAGDM problems using the developed distance formula defined for ITrFNs. Numerical illustration is provided and comparisons are made with some of the existing MAGDM models and ranking procedures.
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Moya Zamora, Jorge, Sara Bastos Gutiérrez, and Alvaro Álvarez Calderón. "Parámetros de transformación entre los marcos geodésicos CR05 y CR-SIRGAS contemplando diferentes soluciones ITRF." Revista Ingeniería 31, no. 1 (January 29, 2021): 21–50. http://dx.doi.org/10.15517/ri.v31i1.43854.
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La oficialización del marco CR-SIRGAS implica la necesidad de transformar la información vinculada al marco anterior a esta nueva referencia nacional. Se presentan los resultados de un análisis efectuado en la determinación de varios conjuntos de parámetros de transformación entre el antiguo marco geodésico CR05 y el marco geodésico CR-SIRGAS. Este proceso contempló el estudio de la transformación directa entre ambos marcos contemplando dos variantes, así como también, una secuencia de transformaciones igualmente en dos variantes considerando las soluciones ITRF que se han dado desde la implementación del CR05. Este proceso denominado transformación en escalera consideró la afectación que produjo el terremoto de Mw 7,6 en la península de Nicoya en agosto de 2012 [1] y [2] sobre los vértices de la red geodésica nacional activa y pasiva del CR05. Considerar los aspectos geométrico y físico es indispensable en una adecuada y correcta georreferenciación. Se usó el modelo de transformación baricéntrico [3] y [4] para seis parámetros: las tres traslaciones entre los orígenes y las tres rotaciones de los ejes [5]. En cada uno de los procesos de cálculo se analizaron los residuales en componentes topocéntricas [N, E, U]. Se ofrece como resultado dos conjuntos de seis parámetros de transformación desde el marco nacional CR05, época de referencia 2005,83, marco ITRF2000 al marco nacional CR-SIRGAS, época de referencia 2014,59, marco ITRF2008. Además, de dos conjuntos de seis parámetros entre CR05 y CR-SIRGAS contemplando diferentes soluciones ITRF y sus respectivas épocas. En cada determinación se expone el comportamiento de los residuales.
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RAMOS, MARCONY DE PAULO, WILLIAM RODRIGO DAL POZ, and ALESSANDRO SALLES CARVALHO. "ANÁLISE DAS POSSIBILIDADES DE TRANSFORMAÇÃO DE REFERENCIAL E ATUALIZAÇÃO DE COORDENADAS ESTIMADAS PELO PPP." Boletim de Ciências Geodésicas 22, no. 3 (September 2016): 389–404. http://dx.doi.org/10.1590/s1982-21702016000300022.
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O sistema de referência oficial adotado no Brasil é o SIRGAS2000 (densificação do ITRF2000) e foi realizado na época 2000,4. Desde a semana GPS 1709 (07/10/2012), o referencial adotado pelo IGS (International GNSS Service) para as efemérides precisas é o IGb08 (ITRF2008). Desse modo, os serviços que realizam o Posicionamento por Ponto Preciso (PPP) e empregam essas efemérides no processamento fornecem as coordenadas das estações nesse referencial e na época de coleta dos dados. Portanto, torna-se necessário realizar a transformação das coordenadas do IGb08 (ITRF2008, época de coleta dos dados) para o SIRGAS2000 (ITRF2000, época 2000,4). Para realizar essa tarefa existem, pelo menos, 45 possibilidades, pois há pelo menos 3 conjuntos de parâmetros de transformação que podem ser usados em conjunto com pelo menos 15 modelos de velocidade. O objetivo deste trabalho é avaliar essas possibilidades no IBGE-PPP. Foram processados dados de 86 estações da RBMC (Rede Brasileira de Monitoramento Contínuo dos Sistemas GNSS) coletados no dia (15/07/2013). Os resultados mostram que a melhor possibilidade de transformação de referencial e atualização de coordenadas, na média, é aquela que utiliza os parâmetros de transformação disponibilizados por Petit e Luzum (2010), juntamente com o modelo de velocidade MORVEL2010.
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Wei, Zhan, Zhu Shuang, Yang Bo, Wu Yanqiang, Liu Zhiguang, and Meng Xiangang. "Effects of the differences between the ITRF2000 and ITRF2005 models in GNSS data processing." Geodesy and Geodynamics 4, no. 4 (2013): 46–50. http://dx.doi.org/10.3724/sp.j.1246.2013.04046.
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Amirrudin, Muhammad Afiq, Ami Hassan Md Din, Nur Adilla Zulkifli, Muhammad Asyran Che Amat, and Mohammad Hanif Hamden. "ASSESSMENT OF THE ACCURACY AND PRECISION OF MyRTKnet REAL-TIME SERVICES." Jurnal Teknologi 83, no. 1 (December 7, 2020): 93–103. http://dx.doi.org/10.11113/jurnalteknologi.v83.13892.
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From a network of ninety-six (96) Continuously Operating Reference Stations (CORS), the Department of Survey and Mapping Malaysia (DSMM) has developed a reliable real-time data streaming service known as the Malaysia Real-Time Kinematic GNSS Network (MyRTKnet). MyRTKnet is now operating on Leica SpiderNet system that is configured to provide coordinate to users in Geocentric Datum of Malaysia 2000 (GDM2000). As the name implied, GDM2000 is a geocentric datum for Malaysia, developed based upon the International Terrestrial Reference Frame (ITRF) 2000 or ITRF2000. One could argue that the quality of coordinates provided by MyRTKnet are less optimal as the latest realisation of ITRF at present is ITRF2014. This study aims to investigate the accuracy and precision of the resultant coordinates from MyRTKnet real-time services through a comparison with the control-quality coordinates from a network of post-processed data at some independent points for positioning purpose. Meanwhile for mapping purpose, the coordinates from Network Real-Time Kinematic (NRTK) at selected Cadastral Reference Marks (CRM) points were compared with their known values. The results show that the observed points in ITRF2000 move approximately 37 cm away from the points in ITRF2014 due to the constant movement of Sundaland Block. Meanwhile for the assessment of NRTK technique, there is no significant displacement for coordinates in ITRF2000 but ITRF2014 with the values of 4.4 and 39.8 cm at KDOJ point, respectively. The discrepancy in ITRF2014 could be due to the improper datum transformation procedure.
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Satirapod, C., Wim J. F. Simons, E. Panumastrakul, and I. Trisirisatayawong. "Updating Thai Reference Frame to ITRF2005 Using GPS: Diversion Between ITRF2000 and 2005 in Southeast Asia." Survey Review 43, no. 319 (January 2011): 45–53. http://dx.doi.org/10.1179/003962610x12747001420906.
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Douša, Jan, and Pavel Václavovic. "Results of GPS reprocessing campaign (1996-2011) provided by Geodetic observatory Pecný." Geoinformatics FCE CTU 9 (December 22, 2012): 77–90. http://dx.doi.org/10.14311/gi.9.7.
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The paper presents the GOP first reprocessing results, which officially contributed to the EPN-repro1 project. It also describes the 15-year GOP cumulative solution providing station coordinates, velocities and their discontinuities over the period of 1996-2011. Repeatabilities estimated from cleaned long-term coordinate time-series reached 1-2 mm and 4-6 mm in horizontal and vertical component, respectively. We then showed the exploitation of GOP reprocessing results in the assessment of the EUREF ITRF2005 densification and the latest ITRS realization, ITRF2008. We identified and confirmed the North-South tilt (≈ 2mas) in the currently available European reference frame based on the EPN cumulative solution updated in GPS week 1600. The study showed a historical development of the tilt and its close relation to a weak velocity datum definition of this realization, which is very important for a long-term datum prediction. Selected EPN station coordinates, velocities and discontinuities of the latest ITRS realization (ITRF2008) were also assessed. Specific problems for some EPN stations were identified in the global reference frame. This emphasized further necessity to check all the stations before their use for datum definition for regional densifications.
Dissertations / Theses on the topic "ITRF00"
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Tiesler, Russell Colin, and n/a. "A Decade of GPS geodesy in the Australian region: a review of the GDA94 and its performance within a time series analysis of a 10 year data set in ITRF 2000." University of Canberra. Information Sciences & Engineering, 2005. http://erl.canberra.edu.au./public/adt-AUC20051202.114435.
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The University of Canberra (UC) has been involved in GPS processing since the late 1980s. This processing commenced with the GOTEX 1988 campaign and progressed through a series of project specific regional campaigns to the current daily processing of a distributed set of continuously operating sites for the determination of precise GPS station positions for user applications. Most of these earlier campaigns covered only short periods of time, ranging from a few weeks to multiple occupations of a few days to a time over one to two years.
With software developments, these multiple occupations were able to be combined to produce results from which crustal motion velocities could be extracted. This first became feasible with the processing of the Australian National Network (ANN), which yielded realistic tectonic velocities from two occupations (1992 and 1993) of sites 12 months apart. Subsequently, this was successfully extended by a further 12 months, with re-occupation of certain sites for a third time in 1994.
Analysis of the results indicated that the accuracy of determining the earth signals improved as the time span from first to last observation was increased. The same was true also for the determination of the position of global references sites. However, by current standards the results achieved were poor.
Consequently, the process was extended to combine the results of subsequent campaigns with the original ANN data set. From 1995 to 1999, campaigns were conducted across Australia, covering many State and tide gauge sites included in the original ANN solution. These provided additional multiple occupations to improve the determinations for both position and velocity. UC has maintained a data set of the global IGS sites, commencing with the IGS pilot campaign of 1992. Daily data sets for those global sites, which contained days common to the regional campaigns, were processed to produce our own independent global orbit and reference frame connection.
The motivation for doing so was fourfold.
�Firstly, to see if historic data could be reprocessed using current modern software and thus be able to be incorporated in this and other analysts research programs.
�Secondly, to compare the results of the reprocessing of the original data set using modern software with the original ANN solution and then validate both the solutions.
�Thirdly, to extend the timespan of observations processed to include more recent campaigns on as many original sites as possible. This to achieve a stronger solution upon which to base the determination of an Australian tectonic plate velocity model and provide quality assurance on the solution comparisons with re-observed sites.
�Fourthly, to develop a set of transformation parameters between current coordinate systems and the GDA94 system so as to be able to incorporate new results into the previous system.
The final selection of regional and global sessions, spanning from mid 1992 to late 2002, contained almost 1000 individual daily solutions. From this 10 year data span a well determined rigid plate tectonic motion model was produced for Australia. This site velocity model was needed to develop a transformation between the thesis solution in ITRF00 an the GDA94 solution in ITRF92. The significant advantage of the plate velocity model is that all Australian sites can now have computed a realistic velocity, rather than being given a value which has been interpolated between sites whose velocities had been determined over a one or two year span. This plate velocity model is compared with the current tectonic motion NNR-NUVEL-1A model and other recently published models.
To perform the comparison between the thesis solution in ITRF00 and the GDA solution in ITRF92 a transformation was developed between the two reference systems. This set of transformation parameters, in conjunction with the plate velocity model developed, enables site solutions at any epoch in the current ITRF00 to be converted onto the GDA94, and vice versa, with a simple, non-varying seven parameter transformation.
The comparisons between the solutions are analysed for both horizontal position and height consistency. There were 77 sites whose differences were compared. The horizontal consistency was within estimated precisions for 75 of the 77 sites. However, the vertical comparisons revealed many of the single epoch sites, especially in 1992, have inconsistent results between the two solutions. The heights from this thesis for some West Australian sites were compared with analysis done by DOLA and the height recoveries are very similar, indicating a weakness in the GDA94 solution for some of the single epoch sites. Some of these differences have been resolved but others are still under investigation.
This thesis describes the repocessing of the original ANN data set, the addition of later data sets, the results obtained, and the validation comparisons of the old and new solutions. As well as the plate velocity model, transformation is provided which enables the user to compute between the GDA94 system, and any epoch result in ITRF00.
Recommendations are made as to which sites need additional work. This includes sites which only need further analysis or investigation and those which require further observations to achieve a result which will have acceptable accuracy and reliability.
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Rebischung, Paul. "Can GNSS contribute to improving the ITRF definition ?" Observatoire de Paris, 2014. https://hal.science/tel-02095157.
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Les systèmes globaux de navigation par satellite (GNSS) jouent un rôle fondamental dans l’élaboration du repère international de référence terrestre (ITRF). Cependant, les GNSS ne se sont jusqu’à présent pas révélés aptes à déterminer de manière fiable l’échelle terrestre ni la position du centre de masse de la Terre (géocentre) et n’ont donc pas contribué à définir l’échelle de l’ITRF ni son origine. L’incapacité des GNSS à déterminer l’échelle terrestre indépendamment de biais conventionnels de centres de phase satellites est un problème bien connu. En revanche, leur incapacité à correctement observer le mouvement du géocentre restait jusqu’alors inexpliquée. Nous avons étudié cette question sous l’angle de la colinéarité entre paramètres d’un ajustement par moindres carrés. Pour prendre en compte plusieurs particularités du problème de la détermination du géocentre par GNSS, un diagnostic de colinéarité généralisé a été développé. Il a ainsi été mis en évidence que la détermination du géocentre par GNSS est sujette à de sérieux problèmes de colinéarité à cause de l’estimation simultanée de décalages d’horloges et de paramètres troposphériques dans les analyses de données GNSS. Différentes pistes ont finalement été étudiées en vue d’une possible future contribution des GNSS à la définition de l’échelle et de l’origine de l’ITRF : l’étalonnage de l’antenne d’au moins un satellite GNSS, l’invariabilité temporelle des biais de centres de phase satellites, l’analyse simultanée de données GNSS acquises par des stations terrestres et des satellites bas, la modélisation d’horloges satellites ultra-stables et la réduction des erreurs de modélisation orbitaleGlobal Navigation Satellite Systems (GNSS) play a fundamental role in the elaboration of the International Terrestrial Reference Frame (ITRF). However, GNSS have so far not proven able to reliably determine the terrestrial scale nor the location of the Earth’s center of mass (geocenter) and have thus not contributed to defining the ITRF scale nor its origin. The weak ability of GNSS to determine the terrestrial scale apart from conventional satellite phase center offsets is well understood. On the other hand, their inability to reliably monitor geocenter motion was so far not clearly explained. We investigated this question from the perspective of collinearity among the parameters of a least-squares regression. A generalized collinearity diagnosis was therefore developed and allows handling several peculiarities of the GNSS geocenter determination problem. It revealed that the determination of all three components of geocenter motion with GNSS suffers from serious collinearity issues due to the simultaneous estimation of epoch-wise station and satellite clock offsets and of tropospheric parameters in global GNSS data analyses. Several prospects were finally investigated in view of a possible future contribution of GNSS to the definition of the ITRF scale and origin: the antenna calibration of at least one GNSS satellite, the time invariability of the satellite phase center offsets, the simultaneous analysis of GNSS data collected by ground stations and low Earth orbiting satellites, the modelling of ultra-stable satellite clocks and the mitigation of orbit modelling errors
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Bruni, Sara. "Combination of GNSS and SLR measurements : contribution to the realization of the terrestrial reference frame." Thesis, Paris Sciences et Lettres (ComUE), 2016. http://www.theses.fr/2016PSLEO001/document.
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La mise en oeuvre exacte et précise du repère international de référence terrestre (ITRF) est une exigence fondamentale pour le développement des Sciences du Système Terre. La réalisation du référentiel mondial, en fait, concerne directement de nombreux domaines allant de la détermination précise des orbites des satellites, à la calibration des altimètres, à l'évaluation des étalonnages absolus d'antennes satellites pour le Global Navigation Satellite System (GNSS) et la validation des corrections du vecteur du centre de masse pour les véhicules spatiaux portant à bord des rétro-réflecteurs pour la technique de télémétrie laser sur satellite (SLR). En conséquence, toutes les études portant sur les mouvements de la surface de la Terre, y compris les océans et les calottes glaciaires, dépendent étroitement de la disponibilité d'un repère de référence fiable qui est fondamental pour référencer les mesures pertinentes. La réalisation de l'ITRF doit alors être périodiquement mise à jour, afin d'intégrer des nouvelles observations et progrès dans les procédures d'analyse des données et/ou des méthodes de combinaison. Toutes les nouvelles stratégies de calcul doivent viser l'amélioration de la réalisation des paramètres physiques du repère, à savoir l'origine et l'échelle, sur lesquels se fondent de façon critique un grand nombre d'études scientifiques et d'applications civiles. Ce travail se concentre sur le potentiel de combiner les observations GNSS et SLR par leur liens à bord de satellites GPS / GLONASS. En fait, les satellites GNSS équipés de rétro-réflecteurs peuvent être observés par les stations SLR, ce qui permet de déterminer les orbites des satellites à travers les deux signaux : optiques et à micro-ondes. En principe, la connexion inter-technique si réalisée pourrait être exploitée pour le calcul de l'ITRF en place des liens terrestres actuellement utilisés. Ces derniers sont connus pour être aujourd'hui un facteur limitant de la précision du repère en raison de leur distribution inhomogène et de leurs divergences avec les estimations de la géodésie spatiale en conséquence des erreurs systématiques dans les observations. Dans cette étude, la force du lien alternatif en orbite a été soigneusement analysée afin d'évaluer les performances de l'approche de combinaison sélectionnée dans les conditions opérationnelles disponibles. L'investigation porte sur la caractérisation de la précision, de la fiabilité et de la pertinence des paramètres combinés du repère de référenceThe accurate and precise implementation of the International Terrestrial Reference Frame (ITRF) is a fundamental requirement for the development of Earth System Sciences. The actual realization of the reference frame, in fact, directly impacts a number of different tasks ranging from precise satellite orbit determination to altimeter calibration, satellite antenna offset assessment for Global Navigation Satellite System (GNSS) and validation of center of mass corrections for spacecrafts carrying on board retro-reflectors for Satellite Laser Ranging (SLR). As a consequence, all the studies investigating motions of the Earth’s surface, including oceans and ice-sheets, strictly depend on the availability of a reliable TRF that is fundamental for geo-referencing the relevant measurements. ITRF realizations must then be periodically updated, in order to account for newly acquired observations and for upgrades in data analysis procedures and/or combination methods. Any innovative computation strategy should ameliorate the realization of the frame physical parameters, namely the origin and the scale, upon which a number of scientific applications critically rely. This work addresses the potential of combining GNSS and SLR observations via their co-location on board GPS/GLONASS satellites. GNSS vehicles equipped with retro-reflector arrays can be tracked by SLR ground stations, which allows determining the spacecraft orbits by means of both optical and microwave signals. In principle, the inter-technique connection so achieved could be exploited for the computation of the ITRF in place of terrestrial ties. These lasts are known to be currently a limiting factor of the frame accuracy because of their inhomogeneous distribution and of their discrepancies with space geodesy estimates due to technique systematic errors. In this study, the strength of the alternative link in orbit has been thoroughly investigated in order to evaluate the performances of the selected space tie approach under the available operational conditions. The analysis focuses on the characterization of the precision, the accuracy and the pertinence of the combined frame parameters
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Benoist, Clément. "Apport de la prise en compte de la dépendance spatiotemporelle des séries temporelles de positions GNSS à l'estimation d'un système de référence." Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLEO011.
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Tout positionnement global précis nécessite un repère de référence tel le repère international de référence terrestre (ITRF). La détermination de l’ITRF s’appuie sur des séries temporelles de positions d’instruments géodésiques, en particulier des stations GNSS permanentes. Les séries temporelles de positions de stations GNSS sont corrélées temporellement et spatialement. De nombreuses études ont caractérisé la dépendance temporelle de ces séries et son impact sur la détermination de repères de référence. En revanche, les corrélations spatiales (entre stations proches) des séries GNSS n’ont jusqu’à présent jamais été prises en compte dans le calcul de repères de référence. L’objectif de cette thèse est donc de proposer une méthodologie pour la prise en compte de ces corrélations spatiales et d’évaluer son apport.Les dépendances spatiales entre les séries de 195 stations GNSS sont tout d’abord évaluées à l’aide de variogrammes empiriques confirmant l’existence de corrélations jusqu’à des distances d’environ 5000 km. Des modèles de covariance exponentielle ne dépendant que de la distance inter-stations sont ajustés sur ces variogrammes empiriques.Une méthodologie basée sur un filtre de Kalman est ensuite développée pour prendre en compte les dépendances spatiales des séries GNSS dans le calcul d’un repère de référence. Trois modèles de dépendance spatiale sont proposés : un modèle ne tenant pas compte de la dépendance spatiale (cas actuel du calcul de l’ITRF), un modèle basé sur les covariances empiriques entre séries de différentes stations, et un modèle basé sur les fonctions de covariance exponentielle mentionnées ci-dessus. Ces différents modèles sont appliqués à trois jeux tests d’une dizaine de stations chacun situés en Europe, aux Caraïbes et sur la côte est des États-Unis. Les trois modèles sont évalués à l’aune d’un critère de validation croisée, c’est-à-dire sur leur capacité à prédire les positions des stations en l’absence de données. Les résultats sur les jeux tests d’Europe et des États-Unis montrent une amélioration considérable de cette capacité prédictive lorsque la dépendance spatiale des séries est prise en compte. Cette amélioration est maximale lorsque le modèle de covariance exponentielle est utilisé. L’amélioration est nettement moindre, mais toujours présente sur le jeu test des Caraïbes.Les trois modèles sont également évalués sur leur capacité à déterminer des vitesses de déplacement exactes à partir de séries temporelles de positions courtes. L’impact de la prise en compte de la dépendance spatiale des séries sur l’exactitude des vitesses estimées est significatif. Comme précédemment, l’amélioration est maximale lorsque le modèle de covariance exponentielle est utilisé.Cette thèse démontre ainsi l’intérêt de la prise en compte des dépendances spatiales entre séries GNSS pour la détermination de repères de référence. La méthodologie développée pourra être utilisée pour le calcul de futures versions de l’ITRFAny global and precise positioning requires a reference frame such as the International Terrestrial Reference Frame (ITRF). The determination of the ITRF relies on the position time series of various geodetic instruments, including in particular permanent GNSS stations. GNSS station position time series are known to be temporally and spatially correlated. Many authors have studied the temporal dependency of GNSS time series and its impact on the determination of terrestrial reference frames. On the other hand, the spatial correlations (i.e., between nearby stations) of GNSS time series have so far never been taken into account in the computation of terrestrial reference frames. The objective of this thesis is therefore to develop a methodology to account for the spatial correlations of GNSS time series, and evaluate its benefits.The spatial dependencies between the position time series of 195 GNSS stations are first evaluated by means of empirical variograms, which confirm the existence of correlations up to distances of about 5000 km. Exponential covariance models, depending only on the distance between stations, are adjusted to these empirical variograms.A methodology based on a Kalman filter is then developed to take into account the spatial dependencies of GNSS time series in the computation of a terrestrial reference frame. Three models of spatial dependency are proposed: a model which does not account for the spatial dependency between GNSS time series (current case of the ITRF computation), a model based on the empirical covariances between the time series of different stations, and a model based on the exponential covariance functions mentioned above.These different models are applied to three test cases of ten stations each, located in Europe, in the Caribbean, and along the east coast of the US. The three models are evaluated with regard to a cross-validation criterion, i.e., on their capacity to predict station positions in the absence of observations. The results obtained with the Europe and US test cases demonstrate a significant improvement of this predictive capacity when the spatial dependency of the series is taken into account. This improvement is highest when the exponential covariance model is used. The improvement is much lower, but still present with the Caribbean test case.The three models are also evaluated with regard to their capacity to determine accurate station velocities from short position time series. The impact of accounting for the spatial dependency between series on the accuracy of the estimated velocities is again significant. Like previously, the improvement is highest when the exponential covariance model is used.This thesis thus demonstrates the interest of accounting for the spatial dependency of GNSS station position time series in the determination of terrestrial reference frames. The developed methodology could be used in the computation of future ITRF versions
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Collilieux, Xavier. "Analyse des séries temporelles de positions des stations de géodésie spatiale : application au Repère International de Référence Terrestre (ITRF)." Observatoire de Paris (1667-....), 2008. https://hal.science/tel-02095044.
Full textAbstract:
Pour la première fois de son histoire, la dernière réalisation en date du Système International de Référence Terrestre, l'ITRF2005, a été générée à partir de séries temporelles de positions de stations des 4 grandes techniques de géodésie spatiale: le Système de Positionnement Global GPS, l'Interférométrie à Très Longue Base, VLBI, la Télémétrie Laser sur Satellite SLR et le système de détermination d'orbite précise de satellite DORIS. Le processus d'estimation de l'ITRF nécessite le calcul des positions et vitesses des stations de ces réseaux qui sont ensuite combinées à l'aide de rattachements locaux dans les sites co-localisés. Dès lors, la disponibilité de séries temporelles de positions permet non seulement la mesure de leurs variations temporelles mais aussi l'étude continuelle des biais globaux affectant les repères estimés. De plus, elle offre la possibilité d'étudier l'accord de ces techniques à un taux d'échantillonnage très élevé. Cette comparaison nécessite le retrait des biais globaux qui, cependant, introduit une erreur appelée "effet de réseau". Cet effet a été étudié à l'aide de données synthétiques et des méthodes permettant de le limiter ont été proposées. Elles ont été appliquées pour comparer les séries temporelles de hauteurs VLBI, SLR et GPS et différentes estimations du mouvement du géocentre. Ces analyses ont permis de mettre en évidence un accord certain à la fréquence annuelle, qui témoigne de la détection des phénomènes de surcharge agissant sur la croûte terrestre. L'utilisation d'un modèle de surcharge dans le processus d'estimation d'un repère séculaire est donc recommandéeFor the first time of its history, the latest to date realization of the International Terrestrial Reference System, the ITRF2005, has been generated from station position time series of the four main space geodetic techniques: the Global Positioning System (GPS), the Very Long Baseline Interferometry (VLBI), the Satellite Laser Ranging (SLR), and the Doppler Orbit determination and Radiopositioning Integrated by Satellite (DORIS). The ITRF computation process consists in stacking the station positions of each technique individually and then combining those using local ties. Meanwhile, time series of station positions allow investigating not only their temporal variations but also global biases that affect reference frame determination. In addition, the current ITRF computation process is a good opportunity to study the agreement of the station position estimations from the space geodetic techniques. To be comparable to each other, global biases which affect stations positions from each technique need to be properly estimated and removed. We have developed some methods to limit the aliasing effect which occurs during this estimation process. These methods have been applied to compare station height time series from VLBI, SLR, and GPS and geocenter motion time series. These analyses have highlighted a certain agreement at the annual frequency, which expresses the detection of loading effects. The use of a loading model in secular frame estimation process is therefore recommended
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Munghemezulu, Cilence. "Determination of geodetic velocity field parameters for the African tectonic plate using the technique of Global Navigation Satellite Systems." Diss., University of Pretoria, 2013. http://hdl.handle.net/2263/40360.
Full textAbstract:
Space geodesy is one of the disciplines that contributes uniquely to the global society; its applications have grown to such an extent that system Earth is better understood today. The current accuracy of the Global Navigation Satellite Systems (GNSS) technique is below centimetre level and this allows very accurate determination of velocity field parameters. This study focused on utilizing GNSS to determine the inter-continental plate velocity field for Africa in support of the African Geodetic Reference Frame (AFREF). Data spanning 12.4 years were processed in the International Terrestrial Reference Frame (ITRF2008) using GAMIT/GLOBK 10.4 (developed at the Massachusetts Institute of Technology). Primarily, processing of data focused on International GNSS Service (IGS) stations with a few non-IGS stations (which are of geodetic quality) included, such as Hamburg (HAMB) and Matjiesfontein (MATJ). The same data set was analysed using the Combination and Analyses of Terrestrial Reference Frame (CATREF) software developed at Institut National de l’Information Géographique et Forestière (IGN). Validation of the results was achieved through comparison of the velocity solution from this study with a solution obtained from a core of IGS GNSS stations processed by the Jet Propulsion Laboratory (JPL). No significant differences were evident between the GAMIT/GLOBK 10.4, CATREF and JPL solutions. The results from the Matjiesfontein station indicated that the proposed Matjiesfontein Observatory site shows no significant vertical or horizontal local motion; this information is valuable in that there is no obvious local site instability. The velocity field as derived by GNSS displays no unexpected deviations and supports current understanding of the motion of the Nubian, Somalian and Arabian plates. Furthermore, the comparison of the velocity vectors derived from the IGS station HRAO, Satellite Laser Ranging (SLR) MOBLAS-6 station and 26 m Very Long Baseline Interferometry (VLBI) telescope, which are collocated at the Hartebeesthoek Radio Astronomy Observatory (HartRAO) indicated good agreement and both techniques exhibit no significant vertical motion. This study also contributed to the first computation of the AFREF solution. It is envisaged that as more stations are added to the sparsely distributed current network, more accurate results and better tectonic models can be derived. The availability of station velocities will facilitate adjustments within the AFREF.Dissertation (MSc)--University of Pretoria, 2013.
gm2014
Geography, Geoinformatics and Meteorology
unrestricted
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Carbone, Rocco. "Il GNSS per il controllo delle deformazioni crostali." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2016.
Find full textAbstract:
Se pensiamo ad un generico punto sulla superficie terreste questo sarà soggetto allo spostamento nel tempo della propria posizione, a causa delle deformazioni della crosta terrestre. Se conosciamo l’intensità e la direzione dello spostamento possiamo esprimere la variazione delle coordinate del punto in un sistema di riferimento geodetico , in funzione del tempo. Varie teorie spiegano la causa di tali deformazioni crostali (ES. La Tettonica a Placche) , attribuendo l’origine a movimenti convettivi del mantello, determinati dalla variazione spaziale della densità ed al progressivo rilascio degli sforzi accumulati nella litosfera a causa del peso delle massi di ghiaccio che, hanno ricoperto parte della superficie terrestre nelle glaciazioni passate. Fin dagli anni’80 il GNSS è divento una tra le tecniche più idonee per andare a valutare lo spostamento della crosta terrestre rispetto ad un sistema di riferimento globale e regionale grazie all’elevato grado di precisione conseguibile.
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Santamaría-Gómez, Alvaro. "Estimation des mouvements verticaux de l'écorce terrestre par GPS dans un repère géocentrique, dans le cadre du projet TIGA." Phd thesis, Observatoire de Paris, 2010. http://tel.archives-ouvertes.fr/tel-00686823.
Full textAbstract:
Deux techniques complémentaires coexistent aujourd'hui pour observer les variations du niveau des mers. L'altimétrie par satellite permet une observation quasi globale avec un échantillonnage temporel et spatial régulier. Cependant, cette technique n'a pas plus de quelques décennies d'existence. A cause des variations inter-décennales du niveau des mers, elle ne donne donc pas accès aux signaux de longue période ou aux variations séculaires. Les variations du niveau des mers à long terme sont accessibles aujourd'hui que grâce aux mesures marégraphiques, certains marégraphes fournissant des enregistrements continus depuis le XIXème siècle. Cette technique constitue donc le seul moyen d'estimer, à partir de la mesure directe, les variations du niveau des mers pendant le XXème siècle, donnée qui représente un bon indicateur du changement climatique. Cependant, les estimations marégraphiques sont contaminées par des mouvements verticaux à long terme de la croûte terrestre. Afin d'obtenir les variations absolues à long terme du niveau des mers, les mouvements verticaux des marégraphes peuvent maintenant être déterminés par la technique GPS. Cette approche est explorée en pratique depuis 2001 par le projet pilote TIGA (Tide Gauge benchmark monitoring) du Service International des GNSS (IGS). Dès 2002, le Consortium ULR (Université de La Rochelle et Institut Géographique National) contribue à ce projet en tant que Centre d'Analyse TIGA. Actuellement, plus de 300 stations GPS globalement reparties sont traitées, parmi lesquelles plus de 200 sont co-localisées avec un marégraphe. Mes travaux de thèse s'inscrivent dans l'étude méthodologique visant à améliorer l'estimation des vitesses verticales des stations GPS. Une première étape de mes travaux a donc consisté en l'étude de la meilleure stratégie de traitement des données GPS. Différentes modélisations ont été testées comme, par exemple, les effets de variation de phase des antennes et du retard troposphérique. A cause du grand nombre de stations du réseau, une répartition en sous-réseaux est imposée pour le traitement. Une répartition optimale des stations GPS selon une approche dynamique a été élaborée et testée. Les résultats ont montré que cette procédure améliore grandement la qualité du traitement GPS. A l'issue de l'application de cette nouvelle stratégie de calcul, on a obtenu et exporté des produits dérivés comme les positions des stations, les orbites des satellites, les paramètres d'orientation de la Terre, et le mouvement apparent du géocentre, pour être combinés dans le cadre de la première campagne de retraitement des données GPS de l'IGS. La confrontation de ces produits avec les produits d'autres analyses de très haute qualité (la grande majorité des Centres d'Analyse IGS y participent) on fourni une validation de la stratégie de traitement GPS implémentée et aussi des indications pour de futures améliorations. La participation à cette campagne a permis en plus de densifier et d'étendre le repère international de référence terrestre (ITRF) aux marégraphes. La deuxième étape de mes travaux a consisté en l'étude de l'estimation de vitesses verticales GPS. L'effet couplé des signaux périodiques et des discontinuités sur les vitesses estimées a été mis en évidence, montrant la nécessité d'estimer ces paramètres d'une manière cohérente et rigoureuse. Particulièrement, l'effet des discontinuités a été signalé comme la source d'erreur la plus importante aujourd'hui pour l'estimation de vitesses. Les incertitudes réalistes des vitesses estimées ont été analysées en profondeur en prenant en compte le contenu de bruit corrélé dans les séries temporelles. En comparant rigoureusement les résultats de cette analyse avec la précédente solution ULR, on constate une réduction significative du contenu du bruit corrélé. Ceci est dû principalement à l'amélioration du traitement des données. Cette analyse du bruit a abouti à la démonstration que la corrélation temporelle des données retraitées de façon homogène dépend de l'époque des données. De cette façon, il a été démontré que le contenu du bruit dans les séries temporelles GPS longues s'explique principalement par le niveau de bruit des données les plus anciennes. Toutefois, pour obtenir l'incertitude formelle de vitesse la plus petite possible, il est nécessaire d'incorporer toutes les données disponibles. Il a été montré qu'en utilisant le modèle de bruit le plus approprié pour la série temporelle de chaque station, l'incertitude formelle du champ de vitesse estimé est en accord avec les différences de vitesse obtenues par rapport à la prochaine réalisation du repère international de référence terrestre, l'ITRF2008.
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Seitz, Manuela. "Kombination geodätischer Raumbeobachtungsverfahren zur Realisierung eines terrestrischen Referenzsystems." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-23388.
Full textAbstract:
Globale terrestrische Referenzsysteme und deren Realisierungen, die sogenannten Referenzrahmen, sind die Grundlage für die Beschreibung der Figur der Erde und ihrer Orientierung im Weltraum sowie für die Referenzierung von Vorgängen auf der Erdoberfläche und im nahen Umfeld der Erde. Die Realisierung des Internationalen Terrestrischen Referenzsystems ist eine der zentralen Aufgaben der Geodäsie. Sie erfolgt durch Kombination von Beobachtungsdaten geodätischer Raumbeobachtungsverfahren. Besondere Bedeutung kommen dabei dem Verfahren der Interferometrie auf sehr langen Basislinien, der Laserentfernungsmessung zu Satelliten sowie dem Globalen Positionierungssystem zu. Jedes dieser Verfahren weist besondere Stärken bei der Bestimmung geodätischer Parameter auf und trägt wesentlich zur Realisierung des Referenzsystems bei. In dieser Arbeit werden Methoden zur Berechnung einer zeitabhängigen und einer zeitunabhängigen Realisierung aus den Beobachtungen der genannten Verfahren entwickelt. Beide Ansätze basieren auf der Kombination bedingungsfreier Normalgleichungen, die aus der homogenen Auswertung der Beobachtungen resultierenden. Diese Vorgehensweise kann als gute Approximation der direkten Kombination der Beobachtungen angesehen werden, die bisher nicht erfolgreich umgesetzt werden konnte. Vom Internationalen Erdrotations- und Referenzsystemdienst (IERS) werden Referenzrahmen basierend auf zeitlich hochaufgelösten Eingangsdaten berechnet. Für die jüngste Lösung des IERS, den ITRF2005, wurden Stationskoordinaten und Erdrotationsparameter (Polkoordinaten und UT1-UTC) erstmalig konsistent ausgeglichen. Entsprechend diesem IERS-Standard werden auch in dieser Arbeit Eingangsdaten mit einer zeitlichen Auflösung von einem Tag beziehungsweise einer Woche verwendet. Zusätzlich zu den genannten Parametern werden Nutations- und bei der zeitunabhängigen Realisierung Troposphärenparameter berücksichtigt. Die zeitabhängige und die zeitunabhängige Realisierung unterscheiden sich hinsichtlich des Zeitraums, aus welchem Beobachtungen berücksichtigt werden und damit hinsichtlich ihrer Parametrisierung, ihres Informationsgehalts, ihres Gültigkeitsbereichs und ihrer Genauigkeit. Es werden spezifische Kombinationsmodelle entwickelt, die diese Eigenschaften berücksichtigen. Da sich Beobachtungen verschiedener Raumbeobachtungsverfahren in aller Regel nicht auf gemeinsame Referenzpunkte beziehen, müssen zur Kombination der Stationsnetze Differenzvektoren zwischen dicht beieinander liegenden Referenzpunkten verschiedener Verfahren eingeführt werden. Die gemessenen Differenzvektoren weisen teilweise große Diskrepanzen zu den Koordinatendifferenzen auf, die aus den Raumbeobachtungsverfahren bestimmt werden. Deshalb müssen geeignete gemessene Differenzvektoren für die Kombination ausgewählt werden. Zwei Kriterien werden für die Auswahl formuliert: Die Konsistenz der kombinierten Lösung soll maximal sein, und die Geometrie der verfahrensspezifischen Stationsnetze soll in der Kombination erhalten bleiben. Zur Quantifizierung der Konsistenz werden die Polkoordinaten herangezogen. Es wird gezeigt, dass diese sich in ihrer Eigenschaft als globale Parameter, die aus allen genannten Beobachtungsverfahren geschätzt werden können, hervorragend zur Beurteilung der Konsistenz eignen. Für beide Realisierungen wird nachgewiesen, dass die Kombination der verschiedenen Beobachtungsverfahren für die Mehrzahl der Parameter zu einer Genauigkeitssteigerung im Vergleich zu den verfahrensspezifischen Lösungen führt. Für einige der Parameter wird eine Verbesserung von 10\% und mehr erreicht. Es wird eine Methode zur Kombination von Troposphärenparametern entwickelt und für die Realisierung des zeitunabhängigen Referenzrahmens getestet. Die Kombination der Troposphärenparameter führt zu einer weiteren Verbesserung der Genauigkeit der kombinierten Lösung. Eine Gegenüberstellung des zeitabhängigen und des zeitunabhängigen Referenzrahmens zeigen die unterschiedlichen Potentiale beider Lösungen. Anhand der Ergebnisse der Arbeit werden Empfehlungen zur Verbesserung öffentlich bereitgestellter Kombinationsprodukte formuliert. Hervorzuheben ist dabei, dass die Kombination der Beobachtungsverfahren auf der Ebene der Normalgleichungen oder - wenn möglich - auf Ebene der Beobachtungsgleichungen durchgeführt werden sollte, und dass die speziellen Eigenschaften der Parameter im Kombinationsprozess besser genutzt werden solltenGlobal terrestrial reference systems and their realizations, the so called reference frames, are fundamental for the description of the Earth's shape and its orientation in space and for referencing changes on the Earth's surface and its planetary environment. The Realization of the International Terrestrial Reference System is one of the main tasks of geodesy. It is achieved by the combination of observation data of different space geodetic techniques. The most important techniques are the Very Long Baseline Interferometry, Satellite Laser Ranging and the Global Positioning System. Each of these techniques has individual strengths with respect to the estimation of geodetic parameters and contributes significantly to the realization of the terrestrial reference system. In this thesis methods are developed, which allow for the realization of a time-dependent as well as for a time-independent reference frame from space observation data. Both methods are based on the combination of free normal equations which result from the homogeneous analysis of the different observation types. This approach is a good approximation for the direct combination of observations, which has not yet been implemented successfully. The International Earth Rotation and Reference Systems Service (IERS) computes reference frames from input data with high temporal resolution. For the most recent solution, the ITRF2005, station coordinates and Earth rotation parameters (pole coordinates and UT1-UTC) were estimated consistently for the first time. In analogy to the IERS standards, input data with daily and weekly resolution are used in this work. In addition to the above mentioned parameters, nutation and troposphere parameters are considered. The time-dependent and the time-independent reference frame are based on observation data of different time spans (two years and one day respectively). Consequently, they are characterised by a different parameterisation and show discrepancies with respect to information content, validity, and accuracy. This requires the development of individual combination models for both realizations. Usually, observations of different space geodetic techniques do not refer to a common reference point. Neighbouring reference points of different techniques are combined by introducing terrestrial difference vectors. In some cases the comparison of the terrestrial difference vectors and the coordinate differences computed from the solutions of the space geodetic techniques show large discrepancies. Thus, the selection of difference vectors which are suitable for the combination is essential. Two criteria for the selection are formulated: The consistency of the combined solution shall be maximal and the geometry of the technique specific station networks shall not be changed by the combination. The consistency is quantified on the basis of the pole coordinates. It is demonstrated, that the pole coordinates are qualified to describe the consistency, since they are global parameters that can be estimated from the observations of all techniques. For both realizations it is shown, that the combination leads to an improvement of accuracy for most of the parameters compared to the technique specific solutions. For some parameters an improvement of 10\% or more is achieved. Additionally, a method for the combination of troposphere parameters is developed and tested for the computation of the time-independent reference frame. The computation of the troposphere parameters leads to a further increase of the accuracy of the combined solution. The comparison of the time-dependent and the time-independent reference frame discloses the individual potentials of both frames. Based on the results, recommendations for the improvement of official combination products are formulated. The most important suggestions are, that the combination of space geodetic techniques shall be performed on the level of normal equations, or if possible on the level of observations. Furthermore, the individual characteristics of the parameters should be used more effectively in the combination process
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Seitz, Manuela. "Kombination geodätischer Raumbeobachtungsverfahren zur Realisierung eines terrestrischen Referenzsystems." Doctoral thesis, Technische Universität Dresden, 2008. https://tud.qucosa.de/id/qucosa%3A25070.
Full textAbstract:
Globale terrestrische Referenzsysteme und deren Realisierungen, die sogenannten Referenzrahmen, sind die Grundlage für die Beschreibung der Figur der Erde und ihrer Orientierung im Weltraum sowie für die Referenzierung von Vorgängen auf der Erdoberfläche und im nahen Umfeld der Erde. Die Realisierung des Internationalen Terrestrischen Referenzsystems ist eine der zentralen Aufgaben der Geodäsie. Sie erfolgt durch Kombination von Beobachtungsdaten geodätischer Raumbeobachtungsverfahren. Besondere Bedeutung kommen dabei dem Verfahren der Interferometrie auf sehr langen Basislinien, der Laserentfernungsmessung zu Satelliten sowie dem Globalen Positionierungssystem zu. Jedes dieser Verfahren weist besondere Stärken bei der Bestimmung geodätischer Parameter auf und trägt wesentlich zur Realisierung des Referenzsystems bei.
In dieser Arbeit werden Methoden zur Berechnung einer zeitabhängigen und einer zeitunabhängigen Realisierung aus den Beobachtungen der genannten Verfahren entwickelt. Beide Ansätze basieren auf der Kombination bedingungsfreier Normalgleichungen, die aus der homogenen Auswertung der Beobachtungen resultierenden.
Diese Vorgehensweise kann als gute Approximation der direkten Kombination der Beobachtungen angesehen werden, die bisher nicht erfolgreich umgesetzt werden konnte.
Vom Internationalen Erdrotations- und Referenzsystemdienst (IERS) werden Referenzrahmen basierend auf zeitlich hochaufgelösten Eingangsdaten berechnet. Für die jüngste Lösung des IERS, den ITRF2005, wurden Stationskoordinaten und Erdrotationsparameter (Polkoordinaten und UT1-UTC) erstmalig konsistent ausgeglichen.
Entsprechend diesem IERS-Standard werden auch in dieser Arbeit Eingangsdaten mit einer zeitlichen Auflösung von einem Tag beziehungsweise einer Woche verwendet. Zusätzlich zu den genannten Parametern werden
Nutations- und bei der zeitunabhängigen Realisierung Troposphärenparameter berücksichtigt.
Die zeitabhängige und die zeitunabhängige Realisierung unterscheiden sich hinsichtlich des Zeitraums, aus welchem Beobachtungen berücksichtigt werden und damit hinsichtlich ihrer Parametrisierung, ihres Informationsgehalts, ihres Gültigkeitsbereichs und ihrer Genauigkeit.
Es werden spezifische
Kombinationsmodelle entwickelt, die diese Eigenschaften berücksichtigen.
Da sich Beobachtungen verschiedener Raumbeobachtungsverfahren in aller Regel nicht auf gemeinsame Referenzpunkte beziehen, müssen zur Kombination der Stationsnetze Differenzvektoren zwischen dicht beieinander liegenden Referenzpunkten verschiedener Verfahren eingeführt werden. Die gemessenen Differenzvektoren weisen teilweise große Diskrepanzen zu den Koordinatendifferenzen auf, die aus den Raumbeobachtungsverfahren bestimmt werden. Deshalb müssen geeignete gemessene Differenzvektoren für die Kombination ausgewählt werden. Zwei Kriterien werden für die Auswahl formuliert: Die Konsistenz der kombinierten Lösung soll maximal sein, und die Geometrie der verfahrensspezifischen Stationsnetze soll in der Kombination erhalten bleiben.
Zur Quantifizierung der Konsistenz werden die Polkoordinaten herangezogen.
Es wird gezeigt,
dass diese sich in ihrer Eigenschaft als globale Parameter, die aus allen genannten Beobachtungsverfahren geschätzt werden können, hervorragend zur Beurteilung der Konsistenz eignen.
Für beide Realisierungen wird nachgewiesen, dass die Kombination der verschiedenen Beobachtungsverfahren für die Mehrzahl der Parameter zu einer Genauigkeitssteigerung im Vergleich zu den verfahrensspezifischen Lösungen führt. Für einige der Parameter wird eine Verbesserung von 10\% und mehr erreicht.
Es wird eine Methode zur Kombination von Troposphärenparametern entwickelt und für die Realisierung des zeitunabhängigen Referenzrahmens getestet. Die Kombination der Troposphärenparameter führt zu einer weiteren Verbesserung der Genauigkeit der kombinierten Lösung.
Eine Gegenüberstellung des zeitabhängigen und des zeitunabhängigen Referenzrahmens zeigen die unterschiedlichen Potentiale beider Lösungen.
Anhand der Ergebnisse der Arbeit werden Empfehlungen zur Verbesserung öffentlich bereitgestellter Kombinationsprodukte formuliert. Hervorzuheben ist dabei, dass die Kombination der Beobachtungsverfahren auf der Ebene der Normalgleichungen oder - wenn möglich - auf Ebene der Beobachtungsgleichungen durchgeführt werden sollte, und dass die speziellen Eigenschaften der Parameter im Kombinationsprozess besser genutzt werden sollten.Global terrestrial reference systems and their realizations, the so called reference frames, are fundamental for the description of the Earth's shape and its orientation in space and for referencing changes on the Earth's surface and its planetary environment. The Realization of the International Terrestrial Reference System is one of the main tasks of geodesy. It is achieved by the combination of observation data of different space geodetic techniques. The most important techniques are the Very Long Baseline Interferometry, Satellite Laser Ranging and the Global Positioning System. Each of these techniques has individual strengths with respect to the estimation of geodetic parameters and contributes significantly to the realization of the terrestrial reference system. In this thesis methods are developed, which allow for the realization of a time-dependent as well as for a time-independent reference frame from space observation data. Both methods are based on the combination of free normal equations which result from the homogeneous analysis of the different observation types. This approach is a good approximation for the direct combination of observations, which has not yet been implemented successfully. The International Earth Rotation and Reference Systems Service (IERS) computes reference frames from input data with high temporal resolution. For the most recent solution, the ITRF2005, station coordinates and Earth rotation parameters (pole coordinates and UT1-UTC) were estimated consistently for the first time. In analogy to the IERS standards, input data with daily and weekly resolution are used in this work. In addition to the above mentioned parameters, nutation and troposphere parameters are considered. The time-dependent and the time-independent reference frame are based on observation data of different time spans (two years and one day respectively). Consequently, they are characterised by a different parameterisation and show discrepancies with respect to information content, validity, and accuracy. This requires the development of individual combination models for both realizations. Usually, observations of different space geodetic techniques do not refer to a common reference point. Neighbouring reference points of different techniques are combined by introducing terrestrial difference vectors. In some cases the comparison of the terrestrial difference vectors and the coordinate differences computed from the solutions of the space geodetic techniques show large discrepancies. Thus, the selection of difference vectors which are suitable for the combination is essential. Two criteria for the selection are formulated: The consistency of the combined solution shall be maximal and the geometry of the technique specific station networks shall not be changed by the combination. The consistency is quantified on the basis of the pole coordinates. It is demonstrated, that the pole coordinates are qualified to describe the consistency, since they are global parameters that can be estimated from the observations of all techniques. For both realizations it is shown, that the combination leads to an improvement of accuracy for most of the parameters compared to the technique specific solutions. For some parameters an improvement of 10\% or more is achieved. Additionally, a method for the combination of troposphere parameters is developed and tested for the computation of the time-independent reference frame. The computation of the troposphere parameters leads to a further increase of the accuracy of the combined solution. The comparison of the time-dependent and the time-independent reference frame discloses the individual potentials of both frames. Based on the results, recommendations for the improvement of official combination products are formulated. The most important suggestions are, that the combination of space geodetic techniques shall be performed on the level of normal equations, or if possible on the level of observations. Furthermore, the individual characteristics of the parameters should be used more effectively in the combination process.
Book chapters on the topic "ITRF00"
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Altamimi, Z., X. Collilieux, and C. Boucher. "Strengthes and Limitations of the ITRF: ITRF2005 and Beyond." In Geodetic Reference Frames, 73–79. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-00860-3_11.
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Altamimi, Z., X. Collilieux, and L. Métivier. "ITRF Combination: Theoretical and Practical Considerations and Lessons from ITRF2008." In Reference Frames for Applications in Geosciences, 7–12. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-32998-2_2.
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Altamimi, Z., P. Sillard, and C. Boucher. "ITRF2000: From Theory to Implementation." In International Association of Geodesy Symposia, 157–63. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/978-3-662-10735-5_21.
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Altamimi, Z. "The International Terrestrial Reference Frame (ITRF2005)." In Geodetic Reference Frames, 81–82. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-00860-3_12.
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Angermann, Detlef, Hermann Drewes, Michael Gerstl, Manuela Krügel, and Barbara Meisel. "DGFI Combination Methodology for ITRF2005 Computation." In Geodetic Reference Frames, 11–16. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-00860-3_2.
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Deleflie, F., D. Coulot, B. de Saint-Jean, O. Laurain, and P. Exertier. "GRGS Evaluation of ITRF2008, from SLR Data." In Reference Frames for Applications in Geosciences, 33–38. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-32998-2_6.
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Boucher, Claude, Zuheir Altamimi, and Patrick Sillard. "The ITRF96 Realization of the International Terrestrial Reference System." In Advances in Positioning and Reference Frames, 57–58. Berlin, Heidelberg: Springer Berlin Heidelberg, 1998. http://dx.doi.org/10.1007/978-3-662-03714-0_8.
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Dermanis, Athanasios. "On the Alternative Approaches to ITRF Formulation." In International Association of Geodesy Symposia, 223–29. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-37222-3_29.
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Sarti, P., C. Abbondanza, and Z. Altamimi. "Local Ties and Co-Location Sites: Some Considerations After the Release of ITRF2008." In Reference Frames for Applications in Geosciences, 75–80. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-32998-2_13.
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Ray, J. R., P. Rebischung, and R. Schmid. "Dependence of IGS Products on the ITRF Datum." In Reference Frames for Applications in Geosciences, 63–67. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-32998-2_11.
Full textConference papers on the topic "ITRF00"
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Moya Zamora, Jorge, and Sara Bastos. "Estimación de los parámetros de transformación al actual marco geodésico nacional de referencia CRSIRGAS." In I Congreso Internacional de Ciencias Exactas y Naturales. Universidad Nacional, 2019. http://dx.doi.org/10.15359/cicen.1.15.
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Con la promulgación del decreto ejecutivo 40692-MJP a inicio del año 2018 y su publicación en el diario oficial, el Instituto Geográfico Nacional de Costa Rica adopta como nuevo marco geodésico nacional el denominado CRSIRGAS. Este marco de referencia está materializado por la estaciones GNSS de operación continua que actualmente administra el IGN y que están vinculadas a la red internacional SIRGAS-CON y que son procesadas semanalmente como parte del mantenimiento del Marco Internacional de Terrestre de Referencia (ITRF). Sin embargo, aunque para el país, este representa un gran avance en materia de actualización geodésica, la promulgación del decreto señala que CRSIRGAS está vinculado al ITRF2008 a la época 2014,59. Lo anterior tiene una serie de implicaciones de tipo topográficas, catastrales, cartográficas, geodésicas y potencialmente legales, ya que de momento no se cuenta con los parámetros necesarios para poder efectuar los distintos procesos de transformación a esta nueva referencia. En este trabajo se exponen los primeros resultados obtenidos en la estimación de los parámetros de transformación entre las referencias geodésicas nacionales y el nuevo CRSIRGAS y de éste al actual ITRF14.
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Aleksejenko, Ivars, Maris Kalinka, Janis Balodis, Inese Janpaule, and Ksenija Kosenko. "LKS-92 coordinates transformation to ITRF2000." In The 9th International Conference "Environmental Engineering 2014". Vilnius, Lithuania: Vilnius Gediminas Technical University Press “Technika” 2014, 2014. http://dx.doi.org/10.3846/enviro.2014.186.
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Sindoni, Giampiero, Claudio Paris, Cristian Vendittozzi, Erricos C. Pavlis, Ignazio Ciufolini, and Antonio Paolozzi. "The Contribution of LARES to Global Climate Change Studies With Geodetic Satellites." In ASME 2015 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/smasis2015-8924.
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Satellite Laser Ranging (SLR) makes an important contribution to Earth science providing the most accurate measurement of the long-wavelength components of Earth’s gravity field, including their temporal variations. Furthermore, SLR data along with those from the other three geometric space techniques, Very Long Baseline Interferometry (VLBI), Global Navigation Satellite Systems (GNSS) and DORIS, generate and maintain the International Terrestrial Reference Frame (ITRF) that is used as a reference by all Earth Observing systems and beyond. As a result we obtain accurate station positions and linear velocities, a manifestation of tectonic plate movements important in earthquake studies and in geophysics in general. The “geodetic” satellites used in SLR are passive spheres characterized by very high density, with little else than gravity perturbing their orbits. As a result they define a very stable reference frame, defining primarily and uniquely the origin of the ITRF, and in equal shares, its scale. The ITRF is indeed used as “the” standard to which we can compare regional, GNSS-derived and alternate frames. The melting of global icecaps, ocean and atmospheric circulation, sea-level change, hydrological and internal Earth-mass redistribution are nowadays monitored using satellites. The observations and products of these missions are geolocated and referenced using the ITRF. This allows scientists to splice together records from various missions sometimes several years apart, to generate useful records for monitoring geophysical processes over several decades. The exchange of angular momentum between the atmosphere and solid Earth for example is measured and can be exploited for monitoring global change. LARES, an Italian Space Agency (ASI) satellite, is the latest geodetic satellite placed in orbit. Its main contribution is in the area of geodesy and the definition of the ITRF in particular and this presentation will discuss the improvements it will make in the aforementioned areas.
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Zhang, Mingchuan, Changqiao Xu, Jianfeng Guan, Qingtao Wu, Ruijuan Zheng, and Hongke Zhang. "B-iTRF: A novel bio-inspired trusted routing framework for wireless sensor networks." In 2014 IEEE Wireless Communications and Networking Conference (WCNC). IEEE, 2014. http://dx.doi.org/10.1109/wcnc.2014.6952678.
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B. Виноградов, A., A. B. Войтенко, and M. C. Куприянов. "Определение координат базовой станции "ВИСХАГИ", находящейся на территории г. Омска, в системе координат ITRF." In GeoSiberia 2007 - International Exhibition and Scientific Congress. European Association of Geoscientists & Engineers, 2007. http://dx.doi.org/10.3997/2214-4609.201403264.
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Zhang, Qinghua, Qinghua Zhang, Fengjuan Rong, Fengjuan Rong, Zhengsheng Chen, and Zhengsheng Chen. "Performance Analysis and Conversion Parameter Evaluation of WGS84/ITRF Ephemeris Framework Implemented by NGA and IGS." In International Workshop on Environment and Geoscience. SCITEPRESS - Science and Technology Publications, 2018. http://dx.doi.org/10.5220/0007430703800385.
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Kaminskis, Janis, Lubova Sulakova, Kalvis Salmins, Janis Kaulins, and Lauris Goldbergs. "SLR and GNSS Test Field for Global Geodetic Network Assessment in Riga." In 11th International Conference “Environmental Engineering”. VGTU Technika, 2020. http://dx.doi.org/10.3846/enviro.2020.718.
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The basic aim is to contribute to the world geodetic space in line with today’s scientific achievements. Riga geodynamic site is a thankful place for this, as it has long-term SLR observations and the longest GNSS records in Latvia. The goal is establishment of regional long-term geodetic monitoring station at LU Institute of Astronomy, Riga, Kandavas street 2, by joining at least two space geodetic technologies – the already installed laser-telescope LS-105 and GNSS − collocated, but not sufficiently linked. The capability of geodetic GNSS observations would uniquely complement Riga GNSS station and allow to determine more accurate coordinates of the LS-105 laser telescope and the long-term changes needed to accurately measure the positions of Earth satellites and other similar space objects. GNSS Observation Station will contribute to the development of positioning and position long-term change to accuracy of less than 1mm, one of the current global goals of GGOS. We plan to solve the problem with the exact position of the telescope LS-105 it will contribute to the development of scientific research and applied potential of the LU Satellite Laser Ranging station. From the national point of view geodetic station serves as an important point for Latvian National Geodetic Network, long term large infrastructure planning, engineering communications, cartography, etc. From a global perspective the station will be one of very few such stations in the region and the only one in the Baltics capable of valuable contribution to ITRF network. Preparatory work for the study has started by selecting and consolidating geodetic points for further measurements.