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GPS estimates of ocean tide loading in NW-France: Determination of ocean tide loading constituents and comparison with a recent ocean tide model / Mathilde Vergnolle in Geophysical journal international, vol 173 n° 2 (May 2008)
[article]
Titre : GPS estimates of ocean tide loading in NW-France: Determination of ocean tide loading constituents and comparison with a recent ocean tide model Type de document : Article/Communication Auteurs : Mathilde Vergnolle, Auteur ; Marie-Noëlle Bouin , Auteur ; Laurent Morel, Auteur ; F. Masson, Auteur ; S. Durand, Auteur ; J. Nicolas, Auteur ; Stavros A. Melachroinos, Auteur Année de publication : 2008 Article en page(s) : pp 444 - 458 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] amplitude
[Termes IGN] analyse harmonique
[Termes IGN] effet de charge
[Termes IGN] France (administrative)
[Termes IGN] marée océanique
[Termes IGN] série temporelleRésumé : (auteur) Ocean loading effects cause 3-D displacements large enough to affect space geodesy measurements either at the subdiurnal periods or at longer time scales by the means of spurious signals. GPS measurements, in turn, could provide local improvements of the models in coastal areas if their ability to precisely monitor such rapid displacements is assessed. In this paper, we use 105 days of continuous GPS measurements collected in 2004 in the French Brittany and Cotentin region to investigate: (1) the precision achieved by the GPS analysis on measuring 3-D subdiurnal displacements and amplitude and phase of the tidal constituents, (2) the quality of the most recent ocean tide model FES2004 in such a complex coastal context. Indeed, in this area, tide amplitudes are among the largest in the world (up to 16 cm of loading displacements on the vertical component) and are believed to show strong shallow-water tides. From a state of the art GPS analysis using the scientific GAMIT software over 2-h sessions, we test two independent strategies for the realization of the reference frame. The position time series are then compared with the displacements predicted by the FES2004 model applied on an elastic Earth model. The two sets of results are consistent with each other at the same level of agreement than with the predicted displacements, namely 3-5 mm on the horizontal components, 10 mm on the vertical. This assesses the capability of this technique for measuring 3-D ocean tide loading deformation. We validate the FES2004 model in the Brittany area, even though it slightly (2-7 mm) underestimates the three components amplitudes. With a harmonic analysis of the observed position time series, we obtain nevertheless an agreement at a submillimetre level for the M2, N2, O1, Q1 tidal constituents and at a millimetre level for the K1 and S2 tidal constituents. Moreover, we can extract a significant M4 load signal at the 95 per cent confidence level from the GPS time series at the stations located in the Mont St Michel area. The detection of other shallow-water constituents would be helpful to understand the amplitude deficit between the FES2004 predicted and GPS observed displacements. Numéro de notice : A2008-616 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1111/j.1365-246X.2008.03734.x Date de publication en ligne : 01/05/2008 En ligne : https://doi.org/10.1111/j.1365-246X.2008.03734.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102899
in Geophysical journal international > vol 173 n° 2 (May 2008) . - pp 444 - 458[article]Terrestrial reference frame implementation in global GPS analysis at TIGA ULR consortium / Guy Wöppelmann in Physics and chemistry of the Earth (A/B/C), vol 33 n° 3-4 ([01/05/2008])
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Titre : Terrestrial reference frame implementation in global GPS analysis at TIGA ULR consortium Type de document : Article/Communication Auteurs : Guy Wöppelmann , Auteur ; Marie-Noëlle Bouin , Auteur ; Zuheir Altamimi , Auteur Année de publication : 2008 Projets : TIGA / Article en page(s) : pp 217 - 224 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] données marégraphiques
[Termes IGN] repère de référence terrestre conventionnel
[Termes IGN] série temporelle
[Termes IGN] verticaleRésumé : (auteur) Monitoring vertical land motion at tide gauges is mandatory if absolute or climate related signals in mean sea level are to be derived from coastal tide gauge records. Different glacial isostatic adjustment models provide very different predictions at the required level of a few tenth of millimetres per year accuracy, while other processes that may affect the vertical stability of tide gauges are still more difficult to predict. An alternative approach is to measure the rates of vertical land motions at the tide gauges. Continuous GPS recordings are presently the most practical and accurate technical solution to address such an issue. The most adequate way to handle the GPS processing seems to be a global scale approach in consistency with the size of the issues: geocentric reference frame realization, long-term stability, global climate change. The laboratories CLDG (Centre Littoral De Géophysique) and LAREG (Laboratoire de Recherches en Géodésie) contribute to the Tide Gauge Benchmark Monitoring (TIGA) IGS pilot project since October 2002 by routinely processing a global set of about 140 GPS sites within the ULR analysis centre consortium. The set comprises about 122 TG-CGPS stations that are analysed using a free network approach. Time series of more than six years are now available. The accuracy of the vertical component is very sensitive to the reference frame definition and realization. We therefore performed some tests in order to quantify the impact of various analysis options on the stability of our realization. We compared the stability of our global solutions with respect to ITRF2000 solution and to its IGS realization called IGS00, while changing the number of reference stations and their geometry. The results indicate that the more reference stations are used the better the alignment to ITRF is performed. A large global distribution of the reference frame stations seems to mitigate individual station problems. The reference frame implementation is achieved within several millimetres accuracy on a weekly basis. The tests indicate that the choice of IGS00 or ITRF2000 datum was not a relevant issue to perform the alignment to ITRF at this level of accuracy. Numéro de notice : A2008-639 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.pce.2006.11.001 Date de publication en ligne : 04/05/2007 En ligne : https://doi.org/10.1016/j.pce.2006.11.001 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=103447
in Physics and chemistry of the Earth (A/B/C) > vol 33 n° 3-4 [01/05/2008] . - pp 217 - 224[article]Comparison of ground-based GPS precipitable water vapour to independent observations and NWP model reanalyses over Africa / Olivier Bock in Quarterly Journal of the Royal Meteorological Society, vol 133 n° 629 (Octobre 2007 part B)
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Titre : Comparison of ground-based GPS precipitable water vapour to independent observations and NWP model reanalyses over Africa Type de document : Article/Communication Auteurs : Olivier Bock , Auteur ; Marie-Noëlle Bouin , Auteur ; Andrea Walpersdorf, Auteur ; Jean-Philippe Lafore, Auteur ; Serge Janicot, Auteur ; Françoise Guichard, Auteur ; Anna Agusti-Panareda, Auteur Année de publication : 2007 Article en page(s) : pp 2011 - 2027 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] Afrique (géographie physique)
[Termes IGN] analyse comparative
[Termes IGN] cohérence des données
[Termes IGN] mousson
[Termes IGN] vapeur d'eauRésumé : (auteur) This study aims at assessing the consistency between different precipitable water vapour (PWV) datasets over Africa (between 35°N and 10°S). This region is characterized by large spatial and temporal variability of humidity but also by the scarcity of its operational observing network, limiting our knowledge of the hydrological cycle. We intercompare data from observing techniques such as ground-based Global Positioning System (GPS), radiosondes, AERONET sun photometers and SSM/I, as well as reanalyses from European Centre for Medium-Range Weather Forecasts (ERA-40) and National Center for Environmental Prediction (NCEP2). The GPS data, especially, are a new source of PWV observation in this region. PWV estimates from nine ground-based GPS receivers of the international GPS network data are used as a reference dataset to which the others are compared. Good agreement is found between observational techniques, though dry biases of 12–14% are evidenced in radiosonde data at three sites. Reasonable agreement is found between the observational datasets and ERA-40 (NCEP2) reanalyses with maximum bias ⩽9% (14%) and standard deviation ⩽17% (20%). Since GPS data were not assimilated in the ERA-40 and NCEP2 reanalyses, they allow for a fully independent validation of the reanalyses. They highlight limitations in the reanalyses, especially at time-scales from sub-daily to periods of a few days. This work also demonstrates the high potential of GPS PWV estimates over Africa for the analysis of the hydrological cycle, at time-scales ranging between sub-diurnal to seasonal. Such observations can help studying atmospheric processes targeted by the African Monsoon Multidisciplinary Analysis project. Numéro de notice : A2007-690 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1002/qj.185 Date de publication en ligne : 20/09/2007 En ligne : https://doi.org/10.1002/qj.185 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102776
in Quarterly Journal of the Royal Meteorological Society > vol 133 n° 629 (Octobre 2007 part B) . - pp 2011 - 2027[article]Assessment of GPS data for meteorological applications over Africa: Study of error sources and analysis of positioning accuracy / Andrea Walpersdorf in Journal of Atmospheric and Solar-Terrestrial Physics, vol 69 n° 12 (August 2007)
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Titre : Assessment of GPS data for meteorological applications over Africa: Study of error sources and analysis of positioning accuracy Type de document : Article/Communication Auteurs : Andrea Walpersdorf, Auteur ; Marie-Noëlle Bouin , Auteur ; Olivier Bock , Auteur ; Erik Doerflinger, Auteur Année de publication : 2007 Article en page(s) : pp 1312 - 1330 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] Afrique tropicale
[Termes IGN] données météorologiques
[Termes IGN] mousson
[Termes IGN] précision du positionnement
[Termes IGN] retard troposphérique zénithal
[Termes IGN] vapeur d'eauRésumé : (auteur) The aim of this study is to assess the availability and quality of data from the International GNSS Service (IGS) Global Positioning System (GPS) network in Africa, especially for retrieving zenith tropospheric delay (ZTD), from which precipitable water vapour (PWV) can be derived, in view of application to the African Monsoon Multidisciplinary Analysis (AMMA) project. Three major error sources for the GPS data analysis evaluating PWV in Africa are the accuracy of the satellite orbits, the correction for the radio delay induced by the ionosphere and the vertical site displacements due to ocean loading. The first part of this study examines these error sources and the validity of GPS data for meteorological applications in Africa in dedicated analyses spanning the year 2001. These analyses were performed using the IGS precise orbits. Weak degradation of baseline precision with increasing baseline lengths suggests that the average orbital error is not limiting the GPS analysis in Africa. The impact of the ionosphere has been evaluated during a maximum of solar activity in 2001. The loss of L2 data has actually been observed. It amounts to 2% on average for 2001, with maxima of 8% during magnetic storm events. A slight decrease in formal accuracy of ZTD seems to be related to the loss of L2 data at the end of the day. This indicates that scintillation effects are present in the GPS observations but however are not a major limitation. The impact of ocean loading is found to be significant on ZTD estimates (up to ±2 mm in equivalent PWV). The use of a proper ocean loading model eliminates this effect.
The second aspect of this study concerns the IGS analysis quality for the African stations. The accuracy has been assessed through position dispersion between individual solutions and the most recent version of the IGS combined solution IGb00, and residuals from the transformation of the IGS combined solution into the International Terrestrial Reference Frame 2005. The positioning performance of the IGS analysis is consistent with an accuracy in ZTD of ±6 mm (±1 mm in PWV), as requested for meteorological applications such as planned in AMMA.Numéro de notice : A2007-672 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.jastp.2007.04.008 Date de publication en ligne : 08/05/2007 En ligne : https://doi.org/10.1016/j.jastp.2007.04.008 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102771
in Journal of Atmospheric and Solar-Terrestrial Physics > vol 69 n° 12 (August 2007) . - pp 1312 - 1330[article]Geocentric sea-level trend estimates from GPS analyses at relevant tide gauges world-wide / Guy Wöppelmann in Global and Planetary Change, vol 57 n° 3-4 (June 2007)
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Titre : Geocentric sea-level trend estimates from GPS analyses at relevant tide gauges world-wide Type de document : Article/Communication Auteurs : Guy Wöppelmann , Auteur ; Bélen Martín Míguez, Auteur ; Marie-Noëlle Bouin , Auteur ; Zuheir Altamimi , Auteur Année de publication : 2007 Article en page(s) : pp 396 - 406 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] déformation verticale de la croute terrestre
[Termes IGN] données marégraphiques
[Termes IGN] International Terrestrial Reference Frame
[Termes IGN] montée du niveau de la merRésumé : (auteur) The problem of correcting the tide gauge records for the vertical land motion upon which the gauges are settled has only been partially solved. At best, the analyses so far have included model corrections for one of the many processes that can affect the land stability, namely the Glacial-Isostatic Adjustment (GIA). An alternative approach is to measure (rather than to model) the rates of vertical land motion at the tide gauges by means of space geodesy. A dedicated GPS processing strategy is implemented to correct the tide gauges records, and thus to obtain a GPS-corrected set of ‘absolute’ or geocentric sea-level trends. The results show a reduced dispersion of the estimated sea-level trends after application of the GPS corrections. They reveal that the reference frame implementation is now achieved within the millimetre accuracy on a weekly basis. Regardless of the application, whether local or global, we have shown that GPS data analysis has reached the maturity to provide useful information to separate land motion from oceanic processes recorded by the tide gauges or to correct these latter. For comparison purposes, we computed the global average of sea-level change according to Douglas [Douglas, B.C., 2001. Sea level change in the era of the recording tide gauge. Int. Geophys. Ser., 75, pp. 37–64.] rules, whose estimate is 1.84 ± 0.35 mm/yr after correction for the GIA effect [Peltier, W.R., 2001. Global glacial isostatic adjustment and modern instrumental records of relative sea level history. Int. Geophys. Ser., 75, pp. 65–95.]. We obtain a value of 1.31 ± 0.30 mm/yr, a value which appears to resolve the ‘sea level enigma’ [Munk, W., 2002. Twentieth century sea level: an enigma. Proc. Natl. Acad. Sci. U.S.A., 99(10), pp. 6550–6555]. Numéro de notice : A2007-687 Affiliation des auteurs : LASTIG+Ext (2016-2019) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.gloplacha.2007.02.002 Date de publication en ligne : 12/02/2007 En ligne : https://doi.org/10.1016/j.gloplacha.2007.02.002 Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102786
in Global and Planetary Change > vol 57 n° 3-4 (June 2007) . - pp 396 - 406[article]Multiscale analysis of precipitable water vapor over Africa from GPS data and ECMWF analyses / Olivier Bock in Geophysical research letters, vol 34 n° 9 (16 May 2007)PermalinkPresent-day crustal deformation around Sagaing fault, Myanmar / Christophe Vigny in Journal of geophysical research : Solid Earth, Vol 108 n° B11 (November 2003)PermalinkCurrent GPS data analysis at CLDG for the IGS TIGA Pilot Project / Guy Wöppelmann in Cahiers bleus du Centre Europeen de Geodynamique et de Séismologie, vol 23 (2003)PermalinkÉtude de la flexion continentale sous la charge océanique à partir des données RGP / Marie-Noëlle Bouin in Bulletin d'information de l'Institut géographique national, n° 73 (septembre 2002)PermalinkNew constraints on Antarctic plate motion and deformation from GPS data / Marie-Noëlle Bouin in Journal of geophysical research : Solid Earth, vol 105 n° B12 ([10/12/2000])PermalinkPermalinkTraitement de données GPS en Antarctique : comment calculer les mouvements du sol / Marie-Noëlle Bouin (1998)PermalinkUne corrélation possible entre "Z" astrométrique et l'indice d'oscillation australe / Z. Li (13/06/1994)PermalinkAnalyse de données astrométriques et climatiques / Marie-Noëlle Bouin (1994)Permalink
Researcher at Lareg until 2008