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A bias-free geodetic boundary value problem approach to height datum unification / Alireza A. Ardalan in Journal of geodesy, vol 84 n° 2 (February 2010)
[article]
Titre : A bias-free geodetic boundary value problem approach to height datum unification Type de document : Article/Communication Auteurs : Alireza A. Ardalan, Auteur ; R. Karimi, Auteur ; Markku Poutanen, Auteur Année de publication : 2010 Article en page(s) : pp 123 - 134 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] cote géopotentielle
[Termes IGN] erreur systématique
[Termes IGN] Finlande
[Termes IGN] géoïde local
[Termes IGN] hauteur ellipsoïdale
[Termes IGN] problème des valeurs limites
[Termes IGN] réseau altimétrique local
[Termes IGN] système de référence altimétriqueRésumé : (Auteur) A geodetic boundary value problem (GBVP) approach has been formulated which can be used for solving the problem of height datum unification. The developed technique is applied to a test area in Southwest Finland with approximate size of 1.5° x 3° and the bias of the corresponding local height datum (local geoid) with respect to the geoid is computed. For this purpose the bias-free potential difference and gravity difference observations of the test area are used and the offset (bias) of the height datum, i.e., Finnish Height Datum 2000 (N2000) fixed to Normaal Amsterdams Peil (NAP) as origin point, with respect to the geoid is computed. The results of this computation show that potential of the origin point of N2000, i.e., NAP, is (62636857.68 1 0.5) (m2/s2) and as such is (0.191 1 0.003) (m) under the geoid defined by W 0 = 62636855.8 (m2/s2). As the validity test of our methodology, the test area is divided into two parts and the corresponding potential difference and gravity difference observations are introduced into our GBVP separately and the bias of height datums of the two parts are computed with respect to the geoid. Obtaining approximately the same bias values for the height datums of the two parts being part of one height datum with one origin point proves the validity of our approach. Besides, the latter test shows the capability of our methodology for patch-wise application. Copyright Springer Numéro de notice : A2010-107 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-009-0348-8 Date de publication en ligne : 10/10/2009 En ligne : https://doi.org/10.1007/s00190-009-0348-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30303
in Journal of geodesy > vol 84 n° 2 (February 2010) . - pp 123 - 134[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 266-2010021 SL Revue Centre de documentation Revues en salle Disponible Fundamental gravity network of the Republic Croatia in the function of control and improving of national and European geoid model / I. Grgic (01/01/2010)
contenu dans Second proceedings of the Croatian Geodetic Institute for the period 2006-2009 / Croatian geodetic institute (2010)
Titre : Fundamental gravity network of the Republic Croatia in the function of control and improving of national and European geoid model Type de document : Article/Communication Auteurs : I. Grgic, Auteur ; B. Barisic, Auteur ; Tomislav Basic, Auteur ; et al., Auteur Editeur : Zagreb [Croatie] : Croatian geodetic institute Année de publication : 01/01/2010 Conférence : CGI 2009, 2nd proceedings of the Croatian Geodetic Institute for the period 2006-2009 Zagreb Croatie Importance : pp 82 - 94 Note générale : Bibliographie Langues : Anglais (eng) Serbo-croate (Latin) (scr) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] Croatie
[Termes IGN] European vertical GPS reference network
[Termes IGN] géoïde localRésumé : (Auteur) By demand for densification of EUVN_DA network with additional points on state territory, Republic Croatia is again activated in project EUVN_DA on national level in year 2005. During project EUVN_DA network is expanded from 8 existing points to 20 points. Difference between EGG97 and EUVN model showed possible errors on some areas or points (HR05 Split). Therefore, those errors were eliminated by measurements and results were free of errors from first EUVN campaign in year 1997. Differences between national model of geoid HRG2000 and EUVN show better adjustment of geoid surface for state area than continen-tal EGG97 geoid. Therefore they are additional control in densification of EUVN_DA project. Result analysis along coast showed large differences between geoid models. From the old gravi-ty network (84 gravity points) 25 gravity points were used. After stabilization of 11 new gravity points Basic Gravity Network comprises 36 gravity points. Finalization of establishment of the Fundamental Gravity Network of the Republic of Croatia is also planned to improve absolute national geoid orientation. As well, EUVN points in Croatia, based on Fundamental Gravity Network, will ensure better identification of geoid differences on continental level. Numéro de notice : C2007-004 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Communication DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=65035 Preliminary works on creation of the new geoid model HRG2009 / I. Grgic (01/01/2010)
contenu dans Second proceedings of the Croatian Geodetic Institute for the period 2006-2009 / Croatian geodetic institute (2010)
Titre : Preliminary works on creation of the new geoid model HRG2009 Type de document : Article/Communication Auteurs : I. Grgic, Auteur ; M. Lucic, Auteur ; Marija Repanic, Auteur ; et al., Auteur Editeur : Zagreb [Croatie] : Croatian geodetic institute Année de publication : 01/01/2010 Conférence : CGI 2009, 2nd proceedings of the Croatian Geodetic Institute for the period 2006-2009 Zagreb Croatie Importance : pp 303 - 312 Note générale : Bibliographie Langues : Anglais (eng) Serbo-croate (Latin) (scr) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] Croatie
[Termes IGN] géoïde altimétrique
[Termes IGN] géoïde local
[Termes IGN] nivellement
[Termes IGN] positionnement par GNSSRésumé : (Auteur) The official Croatian geoid model HRG2000 was developed as a surface for con--version of GNSS-derived ellipsoidal heights into orthometric heights. CROatian POsitionig System (CROPOS), based on 30 permanently working GNSS reference station, had been esta-blished last year. Since HRG2000 geoid model characterizes some weaknesses regarding abso-lute orientation we have used CROPOS service to define new points which will be a base for creation of the new Croatian geiod model HRG2009. For this purpose over the whole Croatian territory more than 500 GNSS/levelling geodetic points were stabilized and measured according to the approximate raster of10x10km. All measured points were connected to the nearest ben-chmarks of the new Croatian vertical datum by precise levelling. The GNSS/Levelling survey provides reliable geoid undulation but only at the points where the survey is made. Therefore for the construction of an accurate HRG2009 geoid model afterwards the gravimetric geo-id model, which should be calculated from all new measured gravity points and old availa-ble gravity data, will befitted to the geoid undulation data from a GNSS/levelling survey. The recently determined geoid undulation calculated from GNSS/Levelling data at the measured geodetic points were analyzed additionally in relation to the geoid undulation from the geoid model HRG2000. The range of geoid undulation and orthometric height differences at measu-red points between old and new geoid model shows an important progress concerning quality in definition of heights for the Republic of Croatia. Numéro de notice : C2009-014 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Communication Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=65054
contenu dans Gravity, Geoid and Earth Observation, IAG Commission 2 Gravity Field, Chania, Crete, Greece, 23-27 June 2008 / Stelios Mertikas (2010)
Titre : Quasi-Geoid of New Caledonia: Computation Results and Analysis Type de document : Article/Communication Auteurs : Pierre Valty , Auteur ; Henri Duquenne (1948-2010) , Auteur Editeur : Berlin, Heidelberg, Vienne, New York, ... : Springer Année de publication : 2010 Collection : International Association of Geodesy Symposia, ISSN 0939-9585 num. 135 Conférence : IAG 2008 Commission 2, Gravity, Geoid and Earth Observation GGEO 23/06/2008 27/06/2008 Chania Crète - Grèce Proceedings Springer Importance : pp 427 - 435 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] géoïde local
[Termes IGN] Nouvelle-Calédonie
[Termes IGN] quasi-géoïdeRésumé : (auteur) The archipelago of New Caledonia is located in the Pacific Ocean, near the New Hebrides Trench. The gravity field is extremely rough in this area, free-air gravity anomalies varying from –230 to +200 mgal. Two vain attempts to compute a geoid model in 2000 and 2004 led the Territorial Government of New Caledonia to put IGN (French National Geographic Institute) in charge of a new calculation. Gravity data were provided by several institutions (Bureau Gravimétrique International, Institut de Recherches pour le Développement, Genavire, IGN) and were of various quality, so that data cleaning has been an important stage. Using the GRAVSOFT package, height anomalies have been computed by the residual terrain method combined with Stokes integration. By comparison of the quasi-geoid with levelled GPS points on the main island, accuracy has been estimated to be better than 9 cm, which shows a significant improvement with previous solutions. A grid to convert ellipsoidal heights into heights above mean sea level has been derived from the quasi-geoid and levelled GPS points. Its accuracy is about 4.5 cm. The shifts between vertical reference systems of principal islands of the archipelago have been determined. Differences between the geoid and the mean sea level at tide gauges, and their correlation with oceanic currents have also been studied and discussed in the paper. Numéro de notice : C2008-019 Affiliation des auteurs : LAREG (1991-2011) Thématique : POSITIONNEMENT Nature : Communication nature-HAL : ComAvecCL&ActesPubliésIntl DOI : 10.1007/978-3-642-10634-7_57 Date de publication en ligne : 26/02/2010 En ligne : https://doi.org/10.1007/978-3-642-10634-7_57 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91754 Sea surface topography and marine geoid by airborne laser altimetry and shipborne ultrasound altimetry / Philippe Limpach (2010)
Titre : Sea surface topography and marine geoid by airborne laser altimetry and shipborne ultrasound altimetry Type de document : Thèse/HDR Auteurs : Philippe Limpach, Auteur Editeur : Zurich : Schweizerischen Geodatischen Kommission / Commission Géodésique Suisse Année de publication : 2010 Collection : Geodätisch-Geophysikalische Arbeiten in der Schweiz, ISSN 0257-1722 num. 80 Importance : 208 p. Format : 20 x 30 cm ISBN/ISSN/EAN : 978-3-908440-24-6 Note générale : Bibliographie
Doctoral thesisLangues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] anomalie de pesanteur
[Termes IGN] bathymétrie acoustique
[Termes IGN] Crète (île)
[Termes IGN] données Jason
[Termes IGN] Egée, mer
[Termes IGN] géoïde altimétrique
[Termes IGN] géoïde local
[Termes IGN] geoïde marin
[Termes IGN] géoréférencement direct
[Termes IGN] GPS en mode cinématique
[Termes IGN] GPS en mode différentiel
[Termes IGN] océanographie dynamique
[Termes IGN] relief de la surface de la mer
[Termes IGN] sondage acoustique
[Termes IGN] surface de la mer
[Termes IGN] télémétrie laser aéroporté
[Termes IGN] validation des donnéesIndex. décimale : 30.83 Applications océanographiques de géodésie spatiale Résumé : (Auteur) The aim of this project was to contribute to the improvement of sea level monitoring and to provide local-scale information on the short-wavelength structure of the marine gravity field, by developing enhanced methods for offshore sea surface height observations. The methods include airborne laser altimetry, shipborne ultrasound altimetry and GPS-equipped buoys. In a first step, instrumental aspects of sea surface height observations by airborne and shipborne altimetry were analyzed. Precise position and attitude of the range sensor are crucial for an accurate sea surface height computation. For this purpose, the survey aircraft and boat were equipped with a multi-antenna GPS array and inertial systems. Sea surface heights were computed from the range data by direct georeferencing. Important aspects are the influences of errors in the differential kinematic GPS positioning and in the attitude determination, as well as the calibration of boresight misalignments. In a second step, the obtained sea surface heights were reduced to mean sea surface by applying corrections for geophysical effects, including waves, tides, atmospheric pressure and wind forcing.
In the framework of this work, several regional campaigns for sea surface height surveys based on airborne and shipborne altimetry were carried out in the Eastern Mediterranean Sea. Dedicated surveys, including deployments of GPS buoys, were performed along Jason-1 radar altimetry ground tracks. Airborne laser altimetry data was acquired along densely spaced flight tracks covering an area of 200 by 200km around the western part of the island of Crete, Greece, in the vicinity of the Hellenic Trench. The objective was the determination of a detailed regional geoid and sea surface topography model in the framework of the GAVDOS project, funded by the European Union. Furthermore, several shipborne campaigns for sea surface height observations were carried out in the North Aegean Sea, in the vicinity of the North Aegean Trough.
Based on the airborne and shipborne altimetry data, a high-resolution sea surface topography of the survey areas was computed, with an accuracy of better than 10 cm. Geoid undulations were derived from the sea surface heights by subtracting the mean dynamic ocean topography induced by oceanic currents. Around western Crete, the geoid obtained from airborne laser altimetry is characterized by very large gradients, with an average height difference of 20m along a distance of only 200km and maximum local gradients of 22 cm/km. These gradients are a clear indication for significant gravity effects caused by the bathymetry and the geodynamic system of the Hellenic Trench. In the survey area in the North Aegean Sea, the geoid obtained from shipborne altimetry shows a distinct depression of 1.5 m, indicating a connection with the bathymetry and the geodynamic features of the North Aegean Trough.
The high resolution and accuracy of the sea surface and geoid heights obtained were verified by comparisons with mean sea surface models from multi-mission satellite radar altimetry, as well as with global and regional geoid models. The reduction of the geoid heights for modeled mass effects of topography, bathymetry, marine sedimentary deposits and crust-mantle boundary revealed pronounced gravity anomalies related to the geodynamic processes in the survey areas.Note de contenu : 1 Introduction
1.1 Motivation and Goals
1.2 Geophysical Characteristics of the Eastern Mediterranean
1.3 Former Work by the GGL in Related Fields of Research
1.4 Research Tasks and Project Outline
2 Geoid, Sea Surface and Dynamic Ocean Topography
2.1 Introduction
2.2 Geoid
2.3 Mean Sea Surface
2.4 Sea Level Anomaly
2.5 Dynamic Ocean Topography
2.6 Permanent Tide
3 Geophysical Effects on Sea Surface Heights
3.1 Introduction
3.2 Ocean Waves
3.3 Tides
3.4 Atmospheric Pressure and Wind Forcing
4 Airborne Laser Altimetry
4.1 Introduction
4.2 Instumental Setup
4.3 Laser Ranging
4.4 Laser Backscatter from Sea Surface
5 Shipborne Ultrasound Altimetry
5.1 Introduction
5.2 Instrumental Setup
5.3 Ultrasound Ranging
5.4 Sensor Synchronization
6 Direct Georeferencing
6.1 Introduction
6.2 Basic Principle
6.3 Kinematic GPS Positioning
6.4 Multi-Antenna GPS Attitude Determination
6.5 Boresight Misalignment Calibration in Airborne Altimetry
7 Sea Surface Heights by Airborne Laser Altimetry around Western Crete
7.1 GAVDOS Airborne Laser Altimetry Campaign
7.2 Instantaneous Sea Surface Height Profiles
7.3 Sea Surface Height Corrections
7.4 Repeatability Analysis
7.5 Time-Independent Sea Surface Topography
8 Sea Surface Heights by Shipborne Ultrasound Altimetry in the North Aegean Sea
8.1 Shipborne Ultrasound Altimetry Campaigns
8.2 Instantaneous Sea Surface Height Profiles
8.3 Sea Surface Height Corrections
8.4 Repeatability Analysis
8.5 Time-Independent Sea Surface Topography
9 Validation of Satellite Radar Altimetry Data
9.1 Introduction
9.2 Validation of Jason-1 Data with Airborne Laser Altimetry
9.3 Validation of Mean Sea Surface from Radar Altimetry
10 Geoscientific Exploitation of Airborne Altimetry Data around Western Crete
10.1 Marine Geoid, Gravity Anomalies and Deflections of the Vertical from Sea Surface Heights
10.2 Local Altimetric Geoid vs. Existing Models
10.3 Mean Dynamic Topography Estimation
10.4 Modeled Mass Effects on Geoid Heights and Gravity
10.5 Mass Reduction of Local Altimetric Geoid
11 Geoscientific Exploitation of Shipborne Altimetry Data in the North Aegean Sea
11.1 Marine Geoid, Gravity Anomalies and Deflections of the Vertical from Sea Surface Heights
11.2 Local Altimetric Geoid vs. Existing Models
11.3 Mean Dynamic Topography Estimation
11.4 Modeled Mass Effects on Geoid Heights and Gravity
11.5 Mass Reduction of Local Altimetric Geoid
12 Summary and ConclusionsNuméro de notice : 10369 Affiliation des auteurs : non IGN Autre URL associée : URL ETH Zurich Thématique : POSITIONNEMENT Nature : Thèse étrangère DOI : 10.3929/ethz-a-005876550 En ligne : https://www.sgc.ethz.ch/sgc-volumes/sgk-80.pdf Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=62408 Exemplaires(1)
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