In this case, a point in the nearby region that met the conditions for magnetic measurements was selected. Not all previous locations were suitable for re-measurements. In the last dozen or so years, the network of the magnetic points has been updated by the new measurements of magnetic declination at over 300 points. The unified set of points of the magnetic network with declination reduced to the 2000.5 epoch constituted the base for further studies of geomagnetic field. The Earth’s magnetic field as a temporal-spatial physical phenomenon of a variable, unpredictable nature is, however, difficult to model in a longer period of time.Īt the turn of the centuries the magnetic declination values at the points of the magnetic network were reduced to the 2000.5 epoch using the polynomial function for field modelling, based on the analysis of the actual changes in magnetic declination at repeat stations and in magnetic observatories. This method assumed that changes in the magnetic field at repeat stations can be described using the polynomial of the 3 rd degree as a function of the position of the point (φ, λ) and the measurement epoch. 40–50% on the modelled gravity field from GGMs that include data from GOCE satellite mission.Ī study of changes in the Earth's magnetic field in Poland in the years 1954-2017 reducing the archival values of magnetic declination at the points of the magnetic network to a uniform epochĪbstract: At the turn of the 1980s and 1990s, the Institute of Geodesy and Cartography developed a method of reducing magnetic declination based on 40-year long magnetic observations at repeat stations. The main findings reveal an improvement of ca. The results obtained were analysed and discussed. quasigeoid height and gravity disturbance, obtained from recent GGMs developed with the use of data from DGSMs were evaluated using terrestrial gravity data available in Ethiopia and GNSS/levelling data in Uganda. The main aim of this research is to evaluate the recent GGMs and assess the contribution of DGSMs to the modelling of the Earth’s gravity field over East Africa. On the basis of data from those DGSMs, Global Geopotential Models (GGMs) are continuously developed. Moreover, in, the GRACE-FO (GRACE Follow-On) has been launched to continue the measurements of GRACE satellite mission. On the contribution of dedicated gravity satellite missions to the modelling of the Earth gravity field – A case study of Ethiopia and Uganda in East AfricaĪbstract: Since the first decade of this millennium, the three dedicated gravity satellite missions (DGSMs): CHAMP (Challenging Minisatellite Payload), GRACE (Gravity Recovery and Climate Experiment) and GOCE (Gravity field and steady-state Ocean Circulation Explorer) had remarkably contributed to the modelling of the Earth’s gravity field and its temporal variations. 10, No 1, 2018 Edotorial pages, contents, reviewers of journal to downloadĮdotorial pages, contents, reviewers of journal to download
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