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Troposphere delays from space geodetic techniques, water vapor radiometers, and numerical weather models over a series of continuous VLBI campaigns / Kamil Teke in Journal of geodesy, vol 87 n° 10-12 (October - December 2013)
[article]
Titre : Troposphere delays from space geodetic techniques, water vapor radiometers, and numerical weather models over a series of continuous VLBI campaigns Type de document : Article/Communication Auteurs : Kamil Teke, Auteur ; Tobias Nilsson, Auteur ; Johannes Böhm , Auteur ; Thomas Hobiger, Auteur ; et al., Auteur ; Pascal Willis , Auteur Année de publication : 2013 Article en page(s) : pp 981 - 1001 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] campagne VLBI
[Termes IGN] données DORIS
[Termes IGN] données GNSS
[Termes IGN] données ITGB
[Termes IGN] gradient de troposphère
[Termes IGN] interférométrie à très grande base
[Termes IGN] modèle météorologique
[Termes IGN] propagation troposphérique
[Termes IGN] retard troposphériqueRésumé : (Auteur) Continuous, very long baseline interferometry (VLBI) campaigns over 2 weeks have been carried out repeatedly, i.e., CONT02 in October 2002, CONT05 in September 2005, CONT08 in August 2008, and CONT11 in September 2011, to demonstrate the highest accuracy the current VLBI was capable at that time. In this study, we have compared zenith total delays (ZTD) and troposphere gradients as consistently estimated from the observations of VLBI, Global Navigation Satellite Systems (GNSS), and Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) at VLBI sites participating in the CONT campaigns. We analyzed the CONT campaigns using the state-of-the-art software following common processing strategies as closely as possible. In parallel, ZTD and gradients were derived from numerical weather models, i.e., from the global European Centre for Medium-Range Weather Forecasts (ECMWF) analysis fields, the High Resolution Limited Area Model (European sites), the Japan Meteorological Agency-Operational Meso-Analysis Field (MANAL, over Japan), and the Cloud Resolving Storm Simulator (Tsukuba, Japan). Finally, zenith wet delays were estimated from the observations of water vapor radiometers (WVR) at sites where the WVR observables are available during the CONT sessions. The best ZTD agreement, interpreted as the smallest standard deviation, was found between GNSS and VLBI techniques to be about 5–6 mm at most of the co-located sites and CONT campaigns. We did not detect any significant improvement in the ZTD agreement between various techniques over time, except for DORIS and MANAL. On the other hand, the agreement and thus the accuracy of the troposphere parameters mainly depend on the amount of humidity in the atmosphere. Numéro de notice : A2013-670 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-013-0662-z Date de publication en ligne : 10/10/2013 En ligne : https://doi.org/10.1007/s00190-013-0662-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32806
in Journal of geodesy > vol 87 n° 10-12 (October - December 2013) . - pp 981 - 1001[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 266-2013101 SL Revue Centre de documentation Revues en salle Disponible Multi-technique comparison of troposphere zenith delays and gradients during CONT08 / Kamil Teke in Journal of geodesy, vol 85 n° 7 (July 2011)
[article]
Titre : Multi-technique comparison of troposphere zenith delays and gradients during CONT08 Type de document : Article/Communication Auteurs : Kamil Teke, Auteur ; Johannes Böhm , Auteur ; Tobias Nilsson, Auteur ; Harald Schuh, Auteur ; Peter Steigenberger, Auteur ; Rolf Dach, Auteur ; Robert Heinkelmann, Auteur ; Pascal Willis , Auteur ; et al., Auteur Année de publication : 2011 Article en page(s) : pp 395 - 413 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] analyse comparative
[Termes IGN] données DORIS
[Termes IGN] données GPS
[Termes IGN] données ITGB
[Termes IGN] données WVR
[Termes IGN] gradient de troposphère
[Termes IGN] retard troposphérique
[Termes IGN] troposphèreRésumé : (Auteur) CONT08 was a 15 days campaign of continuous Very Long Baseline Interferometry (VLBI) sessions during the second half of August 2008 carried out by the International VLBI Service for Geodesy and Astrometry (IVS). In this study, VLBI estimates of troposphere zenith total delays (ZTD) and gradients during CONT08 were compared with those derived from observations with the Global Positioning System (GPS), Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS), and water vapor radiometers (WVR) co-located with the VLBI radio telescopes. Similar geophysical models were used for the analysis of the space geodetic data, whereas the parameterization for the least-squares adjustment of the space geodetic techniques was optimized for each technique. In addition to space geodetic techniques and WVR, ZTD and gradients from numerical weather models (NWM) were used from the European Centre for Medium-Range Weather Forecasts (ECMWF) (all sites), the Japan Meteorological Agency (JMA) and Cloud Resolving Storm Simulator (CReSS) (Tsukuba), and the High Resolution Limited Area Model (HIRLAM) (European sites). Biases, standard deviations, and correlation coefficients were computed between the troposphere estimates of the various techniques for all eleven CONT08 co-located sites. ZTD from space geodetic techniques generally agree at the sub-centimetre level during CONT08, and—as expected—the best agreement is found for intra-technique comparisons: between the Vienna VLBI Software and the combined IVS solutions as well as between the Center for Orbit Determination (CODE) solution and an IGS PPP time series; both intra-technique comparisons are with standard deviations of about 3–6 mm. The best inter space geodetic technique agreement of ZTD during CONT08 is found between the combined IVS and the IGS solutions with a mean standard deviation of about 6 mm over all sites, whereas the agreement with numerical weather models is between 6 and 20 mm. The standard deviations are generally larger at low latitude sites because of higher humidity, and the latter is also the reason why the standard deviations are larger at northern hemisphere stations during CONT08 in comparison to CONT02 which was observed in October 2002. The assessment of the troposphere gradients from the different techniques is not as clear because of different time intervals, different estimation properties, or different observables. However, the best inter-technique agreement is found between the IVS combined gradients and the GPS solutions with standard deviations between 0.2 and 0.7 mm. Numéro de notice : A2011-331 Affiliation des auteurs : IGN+Ext (1940-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-010-0434-y Date de publication en ligne : 27/04/2011 En ligne : https://doi.org/10.1007/s00190-010-0434-y Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31110
in Journal of geodesy > vol 85 n° 7 (July 2011) . - pp 395 - 413[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 266-2011071 RAB Revue Centre de documentation En réserve L003 Disponible
Titre : Sub-daily parameter estimation in VLBI data analysis : Dissertation carried out in order to obtain the academic degree ”doctor of the technical sciences” under the supervision of o.Univ.-Prof. Dipl.-Ing. Dr.techn. Harald Schuh, presented at the Vienna University of Technology, Faculty of Mathematics and Geoinformation, Institute of Geodesy and Geophysics Type de document : Thèse/HDR Auteurs : Kamil Teke, Auteur ; Harald Schuh, Directeur de thèse Editeur : Vienne [Autriche] : Vienna University of Technology Année de publication : 2011 Importance : 275 p. Format : 21 x 30 cm Note générale : Bibliographie
thèse étrangèreLangues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] analyse comparative
[Termes IGN] compensation par moindres carrés
[Termes IGN] données ITGB
[Termes IGN] estimation des paramètres
[Termes IGN] estimation statistique
[Termes IGN] horloge
[Termes IGN] propagation troposphérique
[Termes IGN] rotation de la TerreIndex. décimale : THESE Thèses et HDR Résumé : (Auteur) The main objective of the work carried out within the scope of this thesis is the contribution to the VLBI2010 project of the International Very Long Baseline Interferometry (VLBI) Service for Geodesy and Astrometry (IVS) by means of developing a parameter estimation module (vie lsm) of Vienna VLBI Software (VieVS) which is capable of estimating accurate sub-daily VLBI geodetic parameters. The vie lsm module is based on the classical Gauss Markoff Least-Squares (LS) adjustment method by using continuous piece-wise linear offset (CPWLO) functions which are estimated at unique epochs, e.g. at integer hours, or at integer fractions or integer multiples of integer hours. The interval for CPWLO modelling of the parameters is usually set to values between one day to five minutes.
To investigate the sub-daily tidal motions of the VLBI antennas during IVS-CONT05, hourly CPWLO Terrestrial Reference Frame (TRF) coordinates of the antennas were estimated. Although all tidal displacements are computed from state-of-the-art geophysical models and reduced from the observations a priori to the adjustment, the radial amplitudes from the estimated hourly antenna coordinates can reach up to 1 cm (Kokee, HartRAO, Gilcreek, Westford, Svetloe, and Wettzell). To analyze the high frequency (sub-daily) Earth rotation parameter (HF-ERP) estimates of VieVS during IVS-CONT08, hourly CPWLO ERP were estimated. The Fourier spectra of the hourly VLBI and Global Positioning System (GPS) ERP estimates and the HFERP models during IVS-CONT08 are in a good agreement at prograde and retrograde 12 hours both for length of day (LOD) and polar motion. However, at 24 hour prograde polar motion the amplitude from GPS is larger by about 100 ìas than VLBI and larger by about 160 ìas than HF-ERP models. Additionally, VieVS LOD and polar motion estimates are noisier than from GPS. This may be due to the fact that no relative constraints between the CPWLO ERP estimates in VLBI analysis were introduced. The estimation of hourly source coordinates was rather intended as test study. As long as hourly CPWLO coordinates of two sources are estimated and the remaining sources are fixed to their a priori Celestial Reference Frame (CRF) i coordinates, parametrization of the Earth Orientation Parameters (EOP) is not critical for the estimated source coordinates. However, investigations on this issue need to be carried out in future, e.g. a lot can be learned from correlations between hourly source coordinates and the observation geometry.
The second aim of this thesis, which is also a very good test of the CPWLO estimates of troposphere zenith delays and gradients, is the contribution to combination studies in the framework of the Global Geodetic Observing System (GGOS) of the International Association of Geodesy (IAG) by multi-technique comparison of zenith total delays (ZTD) and troposphere gradients. In the scope of this issue, VLBI VieVS estimates of troposphere ZTD and gradients during IVS-CONT08 were compared with those derived from observations with the GPS, Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS), and water vapor radiometers (WVR) co-located with the VLBI radio telescopes. ZTD and gradients estimated by space geodetic techniques are compared to those computed by ray-tracing through the profiles of various Numerical Weather Models (NWM), such as the European Centre for Medium-Range Weather Forecasts (ECMWF) (all sites), the Japan Meteorological Agency (JMA) and Cloud Resolving Storm Simulator (CReSS) (Tsukuba in Japan), and the High Resolution Limited Area Model (HIRLAM) (European sites). The best inter space geodetic technique agreement of ZTD during IVS-CONT08 is found between the combined IVS and the International GNSS Service (IGS) solutions with a mean standard deviation of about 6 mm over all sites, whereas the agreement with numerical weather models is between 6 and 20 mm. The standard deviations are generally larger at low latitude sites because of higher humidity, and the latter is also the reason why the standard deviations are larger at northern hemisphere stations during IVS-CONT08 in comparison to IVS-CONT02 which was observed in October 2002. The assessment of the troposphere gradients from the different techniques is not as clear because of different time intervals, different estimation properties, or different observable. However, the best inter-technique agreement is found between the IVS combined gradients and the GPS solutions with standard deviations between 0.2 mm and 0.7 mm. As mentioned before all the comparisons and validation tests on the troposphere products during IVS-CONT08 presented in this thesis provide important information with respect to the planned combination and integration of various observing techniques in the framework of the Global Geodetic Observing System (GGOS) of the International Association of Geodesy (IAG).Note de contenu : 1 Introduction
1.1 VLBI Basics
1.2 Contribution of the thesis and research objectives
1.3 Outline of the thesis
2 VLBI delay model
2.1 Gravitational delay
2.2 Vacuum delay and geometric delay
2.3 Partial derivatives of the VLBI delay model with respect to EOP, antenna and source coordinates
2.4 Continuous piece-wise linear offset (CPWLO) functions for sub-daily parameter estimation
3 Least Squares (LS) Adjustment
3.1 Gauss Markoff model
3.2 Constraining parameters
3.3 Free Network Solution
3.4 Stacking normal equation systems
3.5 Parameter estimation in vie lsm
3.5.1 Handling outliers
4 VLBI clock error
4.1 Modelling and estimating VLBI clock errors based on CPWLO functions
4.1.1 Clock error model
4.1.2 Determining and modelling clock breaks
4.1.3 Clock break error on the VLBI observations and its propagation on estimated VLBI parameters
4.2 Frequency stabilities of the VLBI clocks
5 Troposphere delay
5.1 Troposphere mapping functions
5.2 Troposphere gradients
5.3 Troposphere delays in VieVS
6 Multi-technique comparison of troposphere zenith delays and gradients during IVSCONT
6.1 IVS-CONT08 co-located sites, techniques and solutions
6.1.1 Space geodetic solutions
6.1.2 Water Vapor Radiometer (WVR)
6.1.3 Numerical Weather Models (NWM)
6.2 Agreement criteria for the comparisons and troposphere ties
6.3 Intra-technique comparisons of ZTD
6.4 Inter-technique comparisons of ZTD
6.5 Comparison with IVS-CONT02
6.6 Troposphere gradients comparisons
7 VLBI Baseline Length Repeatability Tests of IVS-R1 and -R4 Sessions
7.1 IVS-R1 and -R4 sessions
7.2 Comparison of baseline length repeatabilities derived from different mapping functions and cut-off angles
8 Analyses of the TRF, EOP, and CRF VLBI estimates
8.1 Analysis of the tidal motions at VLBI antennas: Sub-daily CPWLO coordinate estimates versus tide models during IVS-CONT05
8.2 Analyses of the sub-daily ERP during IVS-CONT08: model versus observations
8.3 Analyses of the sub-daily coordinate time series of several defining sources in ICRF2 during IVS-CONT08
9 Conclusions and OutlookNuméro de notice : 14249 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse étrangère DOI : sans En ligne : https://repositum.tuwien.at/handle/20.500.12708/982 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=62653