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Sensitivity of superconducting gravimeters in central Europe on variations in regional river and drainage basins / C. Kroner in Journal of geodesy, vol 85 n° 10 (October 2011)  

Public [article]  inJournal of geodesy > vol 85 n° 10 (October 2011) . - pp 651 - 659 Titre : Sensitivity of superconducting gravimeters in central Europe on variations in regional river and drainage basins Type de document : Article/Communication Auteurs : C. Kroner, Auteur ; A. Weise, Auteur Année de publication : 2011 Article en page(s) : pp 651 - 659 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] analyse de sensibilité [Termes IGN] barrage [Termes IGN] bassin hydrographique [Termes IGN] champ de pesanteur local [Termes IGN] champ de pesanteur terrestre [Termes IGN] Europe centrale [Termes IGN] gravimètre supraconducteur [Termes IGN] gravimétrie [Termes IGN] modèle hydrographique [Termes IGN] variation Résumé : (Auteur) As underpinned by various studies in the last years, temporal changes of the Earth’s gravity field contain a wealth of information on mass redistribution processes in the Earth’s system particularly associated with variations in continental water storage. By combining satellite and terrestrial observations with superconducting gravimeters (SG) a maximum of information can be gained due to the different temporal and spatial sampling. Esp. the cluster of superconducting gravimeters in central Europe is well suited for studies related to spatial and temporal changes in continental water storage. Due to the distribution of SG sites different sensitivities of the instruments are to be expected on changes in the various river and drainage basins which could, if sufficiently pronounced, be deployed to pinpoint areas in which main discrepancies between modelled and actual water storage changes occur and would thus allow us to fine-tune hydrological models. Based on the Water-Gap Global Hydrological Model (WGHM), this sensitivity of the SG observations is investigated. One compartment of the WGHM is surface water, thus comprising rivers, flooding areas, and major reservoirs. This contribution is given for the total cell of 0.5 0.5 and not localized, e.g. in a riverbed, therefore the question arises to which extent localization or non-localization of this compartment affects the estimate if the respective surface waters are in the vicinity of 50km around the SG stations. It can be shown, however, that the lateral distribution of the surface water masses plays only a negligible role for the central European stations meaning distributed surface water masses are an acceptable simplification when estimating hydrological effects. It emerges that variations in water storage in regions outside central Europe produce comparable effects on gravity at all sites and the impact of basins within central Europe is clearly distinguishable among the SG stations. Numéro de notice : A2011-434 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-011-0471-1 Date de publication en ligne : 26/04/2011 En ligne : https://doi.org/10.1007/s00190-011-0471-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31212 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2011101	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Accuracy assessment of the GPS-TEC calibration constants by means of a simulation technique / Jacques Conte in Journal of geodesy, vol 85 n° 10 (October 2011)  

Public [article]  inJournal of geodesy > vol 85 n° 10 (October 2011) . - pp 707 - 714 Titre : Accuracy assessment of the GPS-TEC calibration constants by means of a simulation technique Type de document : Article/Communication Auteurs : Jacques Conte, Auteur ; F. Azpilicueta, Auteur ; C. Brunini, Auteur Année de publication : 2011 Article en page(s) : pp 707 - 714 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] analyse diachronique [Termes IGN] GPS en mode différentiel [Termes IGN] ionosphère [Termes IGN] propagation ionosphérique [Termes IGN] rayonnement solaire [Termes IGN] teneur totale en électrons [Termes IGN] variation saisonnière Résumé : (Auteur) During the last 2 decades, Global Positioning System (GPS) measurements have become a very important data-source for ionospheric studies. However, it is not a direct and easy task to obtain accurate ionospheric information from these measurements because it is necessary to perform a careful estimation of the calibration constants affecting the GPS observations, the so-called differential code biases (DCBs). In this paper, the most common approximations used in several GPS calibration methods, e.g. the La Plata Ionospheric Model (LPIM), are applied to a set of specially computed synthetic slant Total Electron Content datasets to assess the accuracy of the DCB estimation in a global scale scenario. These synthetic datasets were generated using a modified version of the NeQuick model, and have two important features: they show a realistic temporal and spatial behavior and all a-priori DCBs are set to zero by construction. Then, after the application of the calibration method the deviations from zero of the estimated DCBs are direct indicators of the accuracy of the method. To evaluate the effect of the solar activity radiation level the analysis was performed for years 2001 (high solar activity) and 2006 (low solar activity). To take into account seasonal changes of the ionosphere behavior, the analysis was repeated for three consecutive days close to each equinox and solstice of every year. Then, a data package comprising 24 days from approximately 200 IGS permanent stations was processed. In order to avoid unwanted geomagnetic storms effects, the selected days correspond to periods of quiet geomagnetic conditions. The most important results of this work are: i) the estimated DCBs can be affected by errors around +8 TECu for high solar activity and +3 TECu for low solar activity; and ii) DCB errors present a systematic behavior depending on the modip coordinate, that is more evident for the positive modip region. Numéro de notice : A2011-435 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-011-0477-8 Date de publication en ligne : 15/05/2011 En ligne : https://doi.org/10.1007/s00190-011-0477-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31213 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2011101	RAB	Revue	Centre de documentation	En réserve L003	Disponible