STUDIES OF THE EARTH'S CENTER OF MASS PERIODICAL MOVEMENTS
Рубрики: ОРИГИНАЛЬНЫЕ СТАТЬИ
Авторы:
1.
Institute of astronomy RAS, Moscow, Russia
2.
Institute of astronomy RAS, Moscow, Russia
Тип:
Статья
Страницы:
с 1
по 7
Статус:
Опубликован
Получено:
25.11.2009
Одобрено:
25.11.2009
Опубликовано:
25.11.2009
Язык материала:
английский
Ключевые слова:
terrestrial reference frame, origin movements, satellite geodesy, DORIS
Аннотация (русский):
At present the Earth reference coordinate frame ITRF is realized on the base of space geodesy observations in strictly secular sense with purely linear temporal changes velocities without any conventional models. These linear changes include primarily non modeled geophysical motions, mostly of tectonic origin. In the base of all space geodesy techniques except of VLBI, there are precise orbits of the observable satellites, which are moving under the influence of the Earth gravity field around of the entire Earth's center-of-mass CM. To keep the convention of the coincidence of the terrestrial coordinate system origin with the entire Earth center-of-mass, the first harmonics C1,1, S1,1, C1,0 of the gravity field models, used for orbital calculations, are equated to zero. Studies of the ITRF precision and stability, carried out at the different research centers, INASAN included, show that origin of the coordinate system Geocenter is moving relatively to the center of mass. Besides the main geophysical effects: atmosphere pressure, oceanic tides and currents, ice melting, have been taken into consideration. The annual and semiannual amplitudes of the geocenter variations are not the same for different types of measurements and fluctuate in the interval 1ndash;23nbsp;mm for all three components of the position vector. And Z-component is always 2ndash;3 times more than planar components. The absolute scale of the network is determined with the accuracy around of 0.5times;10-13, that is equivalent 3nbsp;mm in the station height. The further improvement of the ITRF accuracy and stability is possible with the use of more dense and equally distributed tracking networks, equipped with the different types of modern instruments, allowed to minimize systematic errors, characteristic for every usable technique. In this connection the International Association of Geodesy arrived to a decision on the development of the Global Geodetic Observing System GGOS, which will consist of about 40 permanent ground tracking sites, space segment of special research satellites and centers of merging, storage and analyses of the data.
At present the Earth reference coordinate frame ITRF is realized on the base of space geodesy observations in strictly secular sense with purely linear temporal changes velocities without any conventional models. These linear changes include primarily non modeled geophysical motions, mostly of tectonic origin. In the base of all space geodesy techniques except of VLBI, there are precise orbits of the observable satellites, which are moving under the influence of the Earth gravity field around of the entire Earth's center-of-mass CM. To keep the convention of the coincidence of the terrestrial coordinate system origin with the entire Earth center-of-mass, the first harmonics C1,1, S1,1, C1,0 of the gravity field models, used for orbital calculations, are equated to zero. Studies of the ITRF precision and stability, carried out at the different research centers, INASAN included, show that origin of the coordinate system Geocenter is moving relatively to the center of mass. Besides the main geophysical effects: atmosphere pressure, oceanic tides and currents, ice melting, have been taken into consideration. The annual and semiannual amplitudes of the geocenter variations are not the same for different types of measurements and fluctuate in the interval 1ndash;23nbsp;mm for all three components of the position vector. And Z-component is always 2ndash;3 times more than planar components. The absolute scale of the network is determined with the accuracy around of 0.5times;10-13, that is equivalent 3nbsp;mm in the station height. The further improvement of the ITRF accuracy and stability is possible with the use of more dense and equally distributed tracking networks, equipped with the different types of modern instruments, allowed to minimize systematic errors, characteristic for every usable technique. In this connection the International Association of Geodesy arrived to a decision on the development of the Global Geodetic Observing System GGOS, which will consist of about 40 permanent ground tracking sites, space segment of special research satellites and centers of merging, storage and analyses of the data.
Ключевые слова:
terrestrial reference frame, origin movements, satellite geodesy, DORIS
terrestrial reference frame, origin movements, satellite geodesy, DORIS
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