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Topographically induced height errors in predicted atmospheric loading effects / Tonie M. van Dam in Journal of geophysical research : Solid Earth, Vol 115 n° B7 (July 2010)
[article]
Titre : Topographically induced height errors in predicted atmospheric loading effects Type de document : Article/Communication Auteurs : Tonie M. van Dam, Auteur ; Zuheir Altamimi , Auteur ; Xavier Collilieux , Auteur ; Jim Ray, Auteur Année de publication : 2010 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] déformation verticale de la croute terrestre
[Termes IGN] hauteur ellipsoïdale
[Termes IGN] International Terrestrial Reference Frame
[Termes IGN] positionnement par GPS
[Termes IGN] pression atmosphérique
[Termes IGN] résidu
[Termes IGN] série temporelle
[Termes IGN] surcharge atmosphériqueRésumé : (auteur) Atmospheric pressure variations are known to induce vertical displacements of the Earth's surface with magnitudes large enough to be detected by geodetic observations. Estimates of these loading effects are derived using global reanalysis fields of surface pressure as input. The input surface pressure has a minimum spatial sampling, which does not capture true surface pressure variations due to high topographic variability in some regions. In this paper, we investigate the effect that unmodeled topographic variability has on surface pressure estimates and subsequent estimates of vertical surface displacements. We find that the estimated height changes from the topographic surface pressure can be significant (2–4 mm) for sites in regions of high topographic variability. When we compare the estimated height changes to Global Positioning System residuals from the 2005 International Terrestrial Reference Frame Realization, we find that the heights derived from the topographic surface pressure, versus those from the normal surface pressure, perform better at reducing the scatter on the height coordinate time series. Numéro de notice : A2010-657 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1029/2009JB006810 Date de publication en ligne : 29/07/2010 En ligne : https://doi.org/10.1029/2009JB006810 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91744
in Journal of geophysical research : Solid Earth > Vol 115 n° B7 (July 2010)[article]Voir aussiDocuments numériques
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Topographically induced height errors ... - pdf éditeurAdobe Acrobat PDF Impact of loading effects on determination of the International Terrestrial Reference Frame / Xavier Collilieux in Advances in space research, vol 45 n° 1 ([04/01/2010])
[article]
Titre : Impact of loading effects on determination of the International Terrestrial Reference Frame Type de document : Article/Communication Auteurs : Xavier Collilieux , Auteur ; Zuheir Altamimi , Auteur ; David Coulot , Auteur ; Tonie M. van Dam, Auteur ; Jim Ray, Auteur Année de publication : 2010 Article en page(s) : pp 144 - 154 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux
[Termes IGN] effet de charge
[Termes IGN] International Terrestrial Reference Frame
[Termes IGN] modèle linéaire
[Termes IGN] série temporelleRésumé : (Auteur) The International Terrestrial Reference Frame (ITRF), as a realization of the International Terrestrial Reference System (ITRS), is represented by a set of station positions and linear velocities. They are intended to be used as regularized coordinates to which some corrections should be added to access instantaneous coordinates. The latest ITRS realization is the ITRF2005, which has integrated time series of station positions to form long-term solutions for the four space geodetic techniques. Currently, a purely linear model is used to parameterize station displacements in the estimation process, plus occasional discontinuities in case of earthquakes or equipment changes. However the input data have been derived without applying surface loading models and so surface loading effects are supposed to be embedded in the coordinates as measured quantities. We evaluate the effect of applying a posteriori loading corrections, which include the effect of atmospheric, non-tidal ocean, and continental water loading, to time series of positions estimated from Satellite Laser Ranging (SLR), Very Long Baseline Interferometry (VLBI), and Global Positioning System (GPS) data. We notice that they reduce about 50% or more of the annual signals in the translation and scale parameter time series of the SLR and VLBI techniques, except in SLR Z translation. In general, the estimated secular frame definition is negligibly affected and estimated positions and velocities are not significantly modified for stations that have accumulated a large number of observations. A multi-technique combination of such derived frames allows concluding that, for some cases, loading model corrections might degrade co-located station coordinates almost as much as they benefit them. However, most significant improvement of the estimated secular coordinates is observed for stations with less than 100 estimated positions as demonstrated with a multi-technique combination. Numéro de notice : A2010-640 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.asr.2009.08.024 Date de publication en ligne : 01/09/2009 En ligne : https://doi.org/10.1016/j.asr.2009.08.024 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=90717
in Advances in space research > vol 45 n° 1 [04/01/2010] . - pp 144 - 154[article]Anomalous harmonics in the spectra of GPS position estimates / Jim Ray in GPS solutions, vol 12 n° 1 (January 20008)
[article]
Titre : Anomalous harmonics in the spectra of GPS position estimates Type de document : Article/Communication Auteurs : Jim Ray, Auteur ; Zuheir Altamimi , Auteur ; Xavier Collilieux , Auteur ; Tonie M. van Dam, Auteur Année de publication : 2008 Article en page(s) : pp 55 – 64 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] coordonnées GPS
[Termes IGN] erreur systématique
[Termes IGN] série temporelleRésumé : (auteur) Prior studies of the power spectra of GPS position time series have found pervasive seasonal signals against a power-law background of flicker noise plus white noise. Dong et al. (2002) estimated that less than half the observed GPS seasonal power can be explained by redistributions of geophysical fluid mass loads. Much of the residual variation is probably caused by unidentified GPS technique errors and analysis artifacts. Among possible mechanisms, Penna and Stewart (2003) have shown how unmodeled analysis errors at tidal frequencies (near 12- and 24-hour periods) can be aliased to longer periods very efficiently. Signals near fortnightly, semiannual, and annual periods are expected to be most seriously affected. We have examined spectra for the 167 sites of the International GNSS (Global Navigation Satellite Systems) Service (IGS) network having more than 200 weekly measurements during 1996.0–2006.0. The non-linear residuals of the weekly IGS solutions that were included in ITRF2005, the latest version of the International Terrestrial Reference Frame (ITRF), have been used. To improve the detection of common-mode signals, the normalized spectra of all sites have been stacked, then boxcar smoothed for each local north (N), east (E), and height (H) component. The stacked, smoothed spectra are very similar for all three components. Peaks are evident at harmonics of about 1 cycle per year (cpy) up to at least 6 cpy, but the peaks are not all at strictly 1.0 cpy intervals. Based on the 6th harmonic of the N spectrum, which is among the sharpest and largest, and assuming a linear overtone model, then a common fundamental of 1.040 ± 0.008 cpy can explain all peaks well, together with the expected annual and semiannual signals. A flicker noise power-law continuum describes the background spectrum down to periods of a few months, after which the residuals become whiter. Similar sub-seasonal tones are not apparent in the residuals of available satellite laser ranging (SLR) and very long baseline interferometry (VLBI) sites, which are both an order of magnitude less numerous and dominated by white noise. There is weak evidence for a few isolated peaks near 1 cpy harmonics in the spectra of geophysical loadings, but these are much noisier than for GPS positions. Alternative explanations related to the GPS technique are suggested by the close coincidence of the period of the 1.040 cpy frequency, about 351.2 days, to the “GPS year”; i.e., the interval required for the constellation to repeat its inertial orientation with respect to the sun. This could indicate that the harmonics are a type of systematic error related to the satellite orbits. Mechanisms could involve orbit modeling defects or aliasing of site-dependent positioning biases modulated by the varying satellite geometry. Numéro de notice : A2008-568 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-007-0067-7 Date de publication en ligne : 15/05/2007 En ligne : https://doi.org/10.1007/s10291-007-0067-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=103421
in GPS solutions > vol 12 n° 1 (January 20008) . - pp 55 – 64[article]Proceedings of the Workshop IMG-2002 / Olivier Francis (2003)
Titre : Proceedings of the Workshop IMG-2002 : Instrumentation and metrology in gravimetry, October 28-30, 2002, Munsbach Castle (Grand-Duchy of Luxemburg) Type de document : Actes de congrès Auteurs : Olivier Francis, Éditeur scientifique ; Tonie M. van Dam, Éditeur scientifique ; European Centre for Geodynamics and Seismology ECGS (Luxembourg), Auteur ; Bureau international des poids et mesures , Auteur Editeur : Luxembourg : Conseil de l'Europe Année de publication : 2003 Collection : Cahiers du Centre Européen de Géodynamique et de Séismologie num. 22 Conférence : IMG 2002, Instrumentation and metrology in gravimetry 28/10/2002 30/10/2002 Schuttrange Grand Duché du Luxembourg Importance : 179 p. Format : 16 x 23 cm ISBN/ISSN/EAN : 978-2-9599804-9-7 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] Europe (géographie physique)
[Termes IGN] géophysique interne
[Termes IGN] gravimétrie
[Termes IGN] instrument de géodésie
[Termes IGN] métrologie
[Termes IGN] SeismologieNote de contenu : * James E. Faller -- Instrumentation for Old Gravity
* T.M. Niebauer, D. Van Westrum, J.M. Brown, F.J. Klopping, M.A. Ravine -- New Absolute Gradiometer
* Y.M. Zanimonskiy, J. Krynski, V.D. Nagornyi, A.V. Omelchenko, A. Sas-Uhrynowski -- On the Optimal Measuring Strategy for Ballistic Gravimeter
* L. Vitushkin, Z. Jiang, M. Beeker, O. Francis -- Sixth International Comparison of Absolute Gravimeters, ICAG-2001
* O. Francis, T. van Dam -- Processing of the Absolute Data of the 1CAG01
* M. Becker, Z. Jiang, L. Vitushkin -- Adjustment of Gravity Measurements at the Sixth International Comparison of Absolute Gravimeters ICAG-2001
* J. Liard, J. Henton, C. Gagnon, A. Lambert, N. Courtier -- Comparison of Absolute Gravimeters Using Simultaneous Observations
* M. Van Camp, M. Hendrickx, P. Richard, S. Thies, J. Hinderer, M. Amalvict, B. Luck, R. Falk -- Comparisons of the FG5#101, #202, #206 and #209 Absolute Gravimeters at four Different European Sites
* S. Mizushima, A. Ooiwa -- Realization of Reliable Gravity Measurement at the NMIJ/AIST
* M. Vermeer -- Ideas on a Consistent Conceptual Framework for Tidal Reductions in Gravity, Geopotcntial and Positioning
* V. Palinkas, P. Kaspar, M. Lederer -- Effect of the Magnetic Field on LCR Gravimeters
* M. Van Camp -- Man-induced Subsidence in Jülich Observed by the FG5 # 202 Absolute Gravimeter in a Noisy Environment
* M. Van Camp -- Efficiency of Tidal Corrections on Absolute Gravity Measurements at the Membach Station
* D. Simon -- The extreme Warming of the Northern Polar Stratopause in February 1998 and its Effect on the Gravity Field in Europe and North America
* G. Durando, A. Germak -- A New Method of Acquiring Data of Absolute Gravimeter
* G. D'Agostino, S. Desogus, G. Durando, A. Germak, C. Origlia -- Improvements of IMGC Absolute Gravimeter
* W. Zürn, R. Widmer-Schnidrig -- Vertical Acceleration Noise at Seismic Frequencies
* J. Krynski, A. Sas-Uhrynowski, L. Siporski -- Verification of the Absolute Gravity Measurements in Poland
* J. Hinderer, M. Sedighi, R. Bayer, K. Ghazavi, M. Amalvicl, B. Luck, F. Nilforoushan, F. Masson, F. Tavakoli. M. Peyret, Y. Djamour, A. Kouhzare, H. Nankali -- The Absolute Gravity Network in Iran: an Opportunity to Analyse Gravity Changes Caused by Present-Day Tectonic Deformation
* T. Sato, Y. Tamura, K. Matsumoto, K. Asari, H.-P Plag, T.M. van Dam, O. Francis. -- Comparison Between Modeled and Observed Gravity Tidal Parameters at Ny-Alesund, Svalbard
* D. Simon -- The Global Field of Gravity Variations Induced by the Seasonal Warming/Cooling of Atmospheric Air Masses
* P. Medvedev, V. Nepoklonov -- New Results of Geoid and Gravity Field Model Determinations in Russia
* D.L. Schmerge -- The Application of Microgravimetry to Aquifer-Storage Change Monitoring
* J. Verdun, E.E. Klingelé, M. Cocard, A.Geiger, R. Bayer -- Airborne Gravity Measurements Using a LaCoste & Romberg Air-Sea Gravity MeterNuméro de notice : 30094 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Actes Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=35095 ContientRéservation
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