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Modelling of the gravimetric effects induced by vertical air mass shifts / D. Simon (2003)

Public Titre : Modelling of the gravimetric effects induced by vertical air mass shifts Type de document : Monographie Auteurs : D. Simon, Auteur Editeur : Francfort sur le Main : Bundesamt für Kartographie und Geodäsie Année de publication : 2003 Collection : Mitteilungen des Bundesamtes für Kartographie und Geodäsie, ISSN 1436-3445 num. 21 Importance : 100 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-89888-001-5 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] anomalie de pesanteur [Termes IGN] champ de pesanteur terrestre [Termes IGN] masse d'air [Termes IGN] modèle atmosphérique Index. décimale : 30.42 Gravimétrie Résumé : (Auteur) The superconducting gravimeters used within the framework of the Global Geodynamic Project (GGP) performed for the determination of the temporal variations of the gravity field nowadays have a resolution in the NanoGal range and drift rates of only a few µgal/year. This has led to an improvement of the chances to achieve a more precise model-related acquisition of the global gravity field, allowing also gravity field components with lower amplitudes having hitherto remained unconsidered to be modelled and identified by means of the relevant measuring series. These components comprise also the effects of vertical air mass displacements computed on the basis of radiosonde data, which are dealt with in the present contribution. In section 2 first the two models used for demonstrating this effect are described including the geophysical and meteorological fundamentals of modelling. Subsequently, the procram system AMACON developed for this purpose and the single computational steps are explained by test examples (section 3). Following this method, in section 4 the gravity variations caused by vertical air mass displacements in Europe and at the North American East coast for the observation period 1998-2000 are modelled with a sampling rate of 24 hours, for which purpose the measuring data sets of 16 European and 12 American radiosonde stations were used. These data are supplemented by the model curve of a radiosonde station (Neumayer Station, Antarctica) situated on the southern hemisphere, whose seasonal component is deferred, as expected, by 6 months. The data obtained on the order of magnitude of this effect constitute the most important outcome of this modelling project performed on a large regional level. It becomes evident that this gravity component cannot be neglected on any European or North American gravimeter station, given that both its short-period components (period range: 3-50 days) and its seasonal components reach in those areas double amplitudes of 1,5-2,0µgGal. In section 5 the evidence of the modelled gravity effect in gravimetric measuring series is discussed. For this purpose, the data series of the two BKG stations Bad Homburg and Medicina were made use of, which had been subjected to a closer analysis beforehand. It proves that the chances of identifying and eliminating the gravity variations caused by vertical air mass displacements are not so small at all. However, in order to be successful in pursuing this objective the components of the local, regional, and global gravity components as a result of horizontal air mass displacements must be removed more accurately from the measuring series than hitherto, which will now be facilitated when using as basis the current prediction models LM (Local Model) and GME (Global Model) provided by the German Meteorological Service (GMS). Numéro de notice : 13153 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Monographie Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=54896

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
13153-02	30.42	Livre	Centre de documentation	Géodésie	Disponible
13153-01	30.42	Livre	Centre de documentation	Géodésie	Disponible