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Termes IGN > sciences naturelles > sciences de la Terre et de l'univers > géosciences > géophysique interne > géodésie > géodésie physique > figure de la Terre > effet de charge > surcharge océanique
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Seasonal low-degree changes in terrestrial water mass load from global GNSS measurements / Thierry Meyrath in Journal of geodesy, vol 91 n° 11 (November 2017)
[article]
Titre : Seasonal low-degree changes in terrestrial water mass load from global GNSS measurements Type de document : Article/Communication Auteurs : Thierry Meyrath, Auteur ; Tonie M. van Dam, Auteur ; Xavier Collilieux , Auteur ; Paul Rebischung , Auteur Année de publication : 2017 Projets : 1-Pas de projet / Article en page(s) : pp 1 - 22 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] coordonnées GNSS
[Termes IGN] géocentre
[Termes IGN] masse d'eau
[Termes IGN] mouvement du géocentre
[Termes IGN] surcharge océanique
[Termes IGN] variation saisonnièreRésumé : (auteur) Large-scale mass redistribution in the terrestrial water storage (TWS) leads to changes in the low-degree spherical harmonic coefficients of the Earth’s surface mass density field. Studying these low-degree fluctuations is an important task that contributes to our understanding of continental hydrology. In this study, we use global GNSS measurements of vertical and horizontal crustal displacements that we correct for atmospheric and oceanic effects, and use a set of modified basis functions similar to Clarke et al. (Geophys J Int 171:1–10, 2007) to perform an inversion of the corrected measurements in order to recover changes in the coefficients of degree-0 (hydrological mass change), degree-1 (centre of mass shift) and degree-2 (flattening of the Earth) caused by variations in the TWS over the period January 2003–January 2015. We infer from the GNSS-derived degree-0 estimate an annual variation in total continental water mass with an amplitude of (3.49±0.19)×103 Gt and a phase of 70∘±3∘ (implying a peak in early March), in excellent agreement with corresponding values derived from the Global Land Data Assimilation System (GLDAS) water storage model that amount to (3.39±0.10)×103 Gt and 71∘±2∘, respectively. The degree-1 coefficients we recover from GNSS predict annual geocentre motion (i.e. the offset change between the centre of common mass and the centre of figure) caused by changes in TWS with amplitudes of 0.69±0.07 mm for GX, 1.31±0.08 mm for GY and 2.60±0.13 mm for GZ. These values agree with GLDAS and estimates obtained from the combination of GRACE and the output of an ocean model using the approach of Swenson et al. (J Geophys Res 113(B8), 2008) at the level of about 0.5, 0.3 and 0.9 mm for GX, GY and GZ, respectively. Corresponding degree-1 coefficients from SLR, however, generally show higher variability and predict larger amplitudes for GX and GZ. The results we obtain for the degree-2 coefficients from GNSS are slightly mixed, and the level of agreement with the other sources heavily depends on the individual coefficient being investigated. The best agreement is observed for TC20 and TS22, which contain the most prominent annual signals among the degree-2 coefficients, with amplitudes amounting to (5.47±0.44)×10−3 and (4.52±0.31)×10−3 m of equivalent water height (EWH), respectively, as inferred from GNSS. Corresponding agreement with values from SLR and GRACE is at the level of or better than 0.4×10−3 and 0.9×10−3 m of EWH for TC20 and TS22, respectively, while for both coefficients, GLDAS predicts smaller amplitudes. Somewhat lower agreement is obtained for the order-1 coefficients, TC21 and TS21, while our GNSS inversion seems unable to reliably recover TC22. For all the coefficients we consider, the GNSS-derived estimates from the modified inversion approach are more consistent with the solutions from the other sources than corresponding estimates obtained from an unconstrained standard inversion. Numéro de notice : A2017-311 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-017-1028-8 Date de publication en ligne : 25/04/2017 En ligne : http://doi.org/10.1007/s00190-017-1028-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85361
in Journal of geodesy > vol 91 n° 11 (November 2017) . - pp 1 - 22[article]Assessment of continental hydrosphere loading using GNSS measurements / Michał Zygmunt in Reports on geodesy and geoinformatics, vol 101 (June 2016)
[article]
Titre : Assessment of continental hydrosphere loading using GNSS measurements Type de document : Article/Communication Auteurs : Michał Zygmunt, Auteur ; Marcin Rajner, Auteur ; Tomasz Liwosz, Auteur Année de publication : 2016 Article en page(s) : pp 36 - 53 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] déformation de la croute terrestre
[Termes IGN] déformation verticale de la croute terrestre
[Termes IGN] données GNSS
[Termes IGN] fonction de Green
[Termes IGN] modèle hydrographique
[Termes IGN] série temporelle
[Termes IGN] station permanente
[Termes IGN] surcharge océaniqueRésumé : (Auteur) Presented paper is dedicated to problems of deformation of the Earth's crust as a response to the surface loading caused by continental waters. The aim of this study was to specify areas particularly vulnerable to studied deformation and to compare calculated and observed displacements. Information of the continental water volume was taken from the WaterGAP Global Hydrological Model. Calculated values of the deformations were verified with the results obtained with programs SPOTL and grat. Vertical deformations were almost 10 times higher than the deformation in the horizontal plane, for which reason later part of the paper focuses on the former. In order to check agreement of the calculated and observed deformation 23 stations of International GNSS Service (IGS) were selected and divided into three groups (inland, near the shoreline and islands). Before comparison outliers and discontinuities were removed from GNSS observations. Modelled and observed signals were centred. The analysed time series of the vertical displacements showed that only for the inland stations it is possible to effectively remove displacements caused by mass transfer in the hydrosphere. For stations located in the coastal regions or islands, it is necessary to consider additional movement effects resulting from indirect ocean tidal loading or atmosphere loading. Numéro de notice : A2016-651 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1515/rgg-2016-0020 En ligne : http://dx.doi.org/10.1515/rgg-2016-0020 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81870
in Reports on geodesy and geoinformatics > vol 101 (June 2016) . - pp 36 - 53[article]Revisiting the pole tide for and from satellite altimetry / Shailen Desai in Journal of geodesy, vol 89 n° 12 (december 2015)
[article]
Titre : Revisiting the pole tide for and from satellite altimetry Type de document : Article/Communication Auteurs : Shailen Desai, Auteur ; John Wahr, Auteur Année de publication : 2015 Article en page(s) : pp 1233 - 1243 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] altimètre
[Termes IGN] altimétrie satellitaire par radar
[Termes IGN] analyse diachronique
[Termes IGN] géocentre
[Termes IGN] marée terrestre
[Termes IGN] masse d'eau
[Termes IGN] masse de la Terre
[Termes IGN] mouvement du pôle
[Termes IGN] surcharge océaniqueRésumé : (auteur) Satellite altimeter sea surface height observations include the geocentric displacements caused by the pole tide, namely the response of the solid Earth and oceans to polar motion. Most users of these data remove these effects using a model that was developed more than 20 years ago. We describe two improvements to the pole tide model for satellite altimeter measurements. Firstly, we recommend an approach that improves the model for the response of the oceans by including the effects of self-gravitation, loading, and mass conservation. Our recommended approach also specifically includes the previously ignored displacement of the solid Earth due to the load of the ocean response, and includes the effects of geocenter motion. Altogether, this improvement amplifies the modeled geocentric pole tide by 15 %, or up to 2 mm of sea surface height displacement. We validate this improvement using two decades of satellite altimeter measurements. Secondly, we recommend that the altimetry pole tide model exclude geocentric sea surface displacements resulting from the long-term drift in polar motion. The response to this particular component of polar motion requires a more rigorous approach than is used by conventional models. We show that erroneously including the response to this component of polar motion in the pole tide model impacts interpretation of regional sea level rise by ±0.25 mm/year. Numéro de notice : A2015-888 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-015-0848-7 Date de publication en ligne : 27/08/2020 En ligne : https://doi.org/10.1007/s00190-015-0848-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=79436
in Journal of geodesy > vol 89 n° 12 (december 2015) . - pp 1233 - 1243[article]Impact of ocean tides loading on precise point positioning based on FES2004 model / J.Z. Kalita in Artificial satellites, vol 50 n° 2 (June 2015)
[article]
Titre : Impact of ocean tides loading on precise point positioning based on FES2004 model Type de document : Article/Communication Auteurs : J.Z. Kalita, Auteur ; Z. Rzepecka, Auteur Année de publication : 2015 Article en page(s) : pp 77 - 90 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement
[Termes IGN] Pologne
[Termes IGN] positionnement ponctuel précis
[Termes IGN] surcharge océaniqueRésumé : (auteur) Precise Point Positioning (PPP) technique as an absolute positioning method requires modeling of effects that influence observations. One of the effects is a displacement of the measurement location due to ocean mass gravitational attraction - ocean tides loading (OTL). The model recommended by the International Earth Rotation and Reference Systems Service (IERS) is FES2004. The paper focuses on impact of applying the particular OTL model on PPP processing. The analysis is based on processing of observations from 24 globally distributed permanent stations and time span of 50 days. The analysis bases on processing intervals from 1 to 24 hours. In addition, the amplitudes of the loads in Poland are evaluated. The OTL model is location dependent, thus the importance of applying this model depends on the location environment. As the PPP is an absolute method, the loads cumulate and transfer nearly directly to the positioning solution. Consequently, for short observation intervals and small loads the application of the model does not play an important role. For the analysed station with high amplitudes of the loads the relative and absolute improvement, of the solution was the highest for height component. By applying the model, the solution improved by 19% or 7.3 mm (as for RMS and 8 hour interval). The distinct improvement for convergence exists for vertical component and threshold below 5 cm. For Poland the vertical component loads were about 5 times smaller and the highest improvement for the analysed station was 3.7% for 4 hour interval and vertical component. Numéro de notice : A2015-286 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1515/arsa-2015-0006 En ligne : https://doi.org/10.1515/arsa-2015-0006 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76404
in Artificial satellites > vol 50 n° 2 (June 2015) . - pp 77 - 90[article]Non-linear motions of Australian geodetic stations induced by non-tidal ocean loading and the passage of tropical cyclones / A. Mémin in Journal of geodesy, vol 88 n° 10 (October 2014)
[article]
Titre : Non-linear motions of Australian geodetic stations induced by non-tidal ocean loading and the passage of tropical cyclones Type de document : Article/Communication Auteurs : A. Mémin, Auteur ; C. Watson, Auteur ; I. D. Haigh, Auteur Année de publication : 2014 Article en page(s) : pp 927 - 940 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement
[Termes IGN] Australie
[Termes IGN] déformation de la croute terrestre
[Termes IGN] réseau géodésique local
[Termes IGN] surcharge atmosphérique
[Termes IGN] surcharge océanique
[Termes IGN] tempêteRésumé : (Auteur) We investigate daily and sub-daily non-tidal oceanic and atmospheric loading (NTOAL) in the Australian region and put an upper bound on potential site motion examining the effects of tropical cyclone Yasi that crossed the Australian coast in January/February 2011. The dynamic nature of the ocean is important, particularly for northern Australia where the long-term scatter due to daily and sub-daily oceanic changes increases by 20–55 % compared to that estimated using the inverted barometer (IB) assumption. Correcting the daily Global Positioning System (GPS) time series for NTOAL employing either a dynamic ocean model or the IB assumption leads to a reduction of up to 52 % in the weighted scatter of daily coordinate estimates. Differences between the approaches are obscured by seasonal variations in the GPS precision along the northern coast. Two compensating signals during the cyclone require modelling at high spatial and temporal resolution: uplift induced by the atmospheric depression, and subsidence induced by storm surge. The latter dominates ( > 135 %) the combined net effect that reaches a maximum of 14 mm, and 10 mm near the closest GPS site TOW2. Here, 96 % of the displacement is reached within 15 h due to the rapid transit of cyclones and the quasi-linear nature of the coastline. Consequently, estimating sub-daily NTOAL is necessary to properly account for such a signal that can be 3.5 times larger than its daily-averaged value. We were unable to detect the deformation signal in 2-hourly GPS processing and show that seasonal noise in the Austral summer dominates and precludes GPS detection of the cyclone-related subsidence. Numéro de notice : A2014-515 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-014-0734-8 Date de publication en ligne : 12/06/2014 En ligne : https://doi.org/10.1007/s00190-014-0734-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=74119
in Journal of geodesy > vol 88 n° 10 (October 2014) . - pp 927 - 940[article]Réservation
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