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Theoretical prediction and observation evidences on the northward drift and annual oscillation of the Earth’s core from space geodesyтезисы доклада
- Авторы: Barkin Yuri, Jin Shuanggen, WenBin Shen
- Сборник: International Symposium & Summer School on Planetary Science (IAPS)
- Тезисы
- Год издания: 2013
- Место издания: Shanghi Astronomical Observatory, Chinese Academy of Sciences Shanghai, China
- Первая страница: 1
- Последняя страница: 2
- Аннотация: Theoretical prediction and observation evidences on the northward drift and annual oscillation of the Earth’s core from space geodesy Yuri Barkin 1, Shuanggen Jin 2, WenBin Shen 3 1 Sternberg Astronomical Institute at Moscow State University, Moscow, Russia 2 Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030, China 3 School of Geodesy and Geomatics/Key Laboratory of Geospace Environment and Geodesy of Ministry of Education, Wuhan University, Wuhan 430079, China; In the last decades, the contrast changes of the Northern and Southern Hemispheres’ shapes have been investigated using the space geodetic observations, e.g., the secular and annual variations of the volumes, lengths of the circles of latitude and mean radius of the Northern and Southern hemispheres on the basis of current space geodetic data. It has shown the clear secular trend of the center of Earth’s mass, whose mechanism was as a consequence of the secular northward drift of the Earth’s core relative to the mantle. In this paper, the geodetic results on the secular drift and annual oscillation of the core relatively to the mantle in the Earth’s hemispheres are reviewed and presented. Some theoretical assumptions and phenomena are also confirmed as well as the legitimacy and universality of the developed geodynamic model of forced oscillations of the Earth’s core – mantle system (Barkin, 2002). For example, global DORIS observations showed the existence of the secular polar northward drift of the center of Earths’ mass at 5.2 mm/y. This drift reflects the Earth’s core drift at a rate of 27.4±0.8 mm/y (Barkin, 2005), i.e., the drift of the center of the core’s mass relative to the center of the mantle’s mass. The gravitational effect of the shifting core causes deformations of all layers of the mantle and various offsets. As a result, the mean radius of the northern hemisphere increases with the small velocity about 0.01 mm/y, and the mean radius of the southern hemisphere on the contrary decreases with the same magnitude of velocity - 0.01 mm/y. This effect is very difficult for confirmation on the base of satellite observations. Shen et al. (2012) also obtained related results with 0.46 ± -0.01 mm/y and -0.19 ± -0.01 mm/y for northern and southern hemispheres respectively from global geodetic observations at 845 stations. The theoretical value of the largest secular velocity of lengthening of latitudinal circles in the southern hemisphere at latitude 45°S is 5.47 ±-0.12 mm/y, and in the northern hemisphere the secular velocity of shortening of latitudinal circle (for latitude 45°N) is - 5.47±-0.12 mm/y, which are consistent with recent results at secular velocity in 4.5 mm/y and 9.5 mm/y for the northern and southern hemispheres (Barkin and Jin, 2006 and 2007). These geodetic observations results give a good explanation. The asymmetric real changes in the Earth’s shape are apparently related to the formation of the rifting and subduction zones in their asymmetrical arrangement in relation to the Northern and Southern hemispheres. In this paper, we study the effect of the annual planetary geodesic polar oscillations of the core, which corresponds to a unidirectional oscillation of the center of mass of the Earth with an amplitude of 21.3 ± 0.9 mm, and the initial phase of 35.8 ± 3.6º (Kaftan, 2004). The study of solution of the elasticity problem of deformation of the mantle at the annual oscillation of the core of the Earth let us to identify and describe the set new geodetic phenomena. From them the annual variation of the lengths of latitudinal circles, depending on the latitude and time t by the law -22.030cos (360º t - 35.8º) sin2Ф mm. The annual variation of the radial displacements of points on the surface of the mantle of the law 0.133cos (360º t - 35.8º) sinФ mm. And the annual meridian displacements of the points on the surface of the Earth by the law 7.145cos (360º t - 35.8º) cosФ mm. In this report we discuss prospects of geodetic determination of these effects with the annual period on the basis of current space-geodetic data. References. Barkin Y., WenBin Shen, Shuanggen Jin (2013) Geodetic consequences of the northern drift of the Earth’s core and their confirmations in the space geodesy data: the expected related phenomena on the Moon and Mars. Japan Geosciene Union Meeting (19-24 May 2013, Makuhari Messe, Chiba, Japan). P-PS03-P01. Abstracts. https://secure.jtbcom.co.jp/jpgu_e/program/DisplayContributionPDF.asp
- Добавил в систему: Баркин Юрий Владимирович
Прикрепленные файлы
| № | Имя | Описание | Имя файла | Размер | Добавлен |
|---|---|---|---|---|---|
| 1. | Краткий текст | BARKIN_2_GEODESY_CHANGES_1.doc | 36,5 КБ | 2 декабря 2013 [BarkinYV] | |
| 2. | Краткий текст | BARKIN_2_GEODESY_CHANGES.doc | 36,5 КБ | 2 декабря 2013 [BarkinYV] |