Number of the records: 1
Excitation of the Earth’s Orientation by Geophysical fluids and Geomagnetic Jerks
- 1.
SYSNO ASEP 0539408 Document Type C - Proceedings Paper (int. conf.) R&D Document Type Conference Paper Title Excitation of the Earth’s Orientation by Geophysical fluids and Geomagnetic Jerks Author(s) Ron, Cyril (ASU-R) RID, ORCID
Vondrák, Jan (ASU-R) RID, ORCIDSource Title Proceedings of the Journées 2017: Futhering our knowledge of Earth rotation. - Paris : Observatoire de Paris, 2020 / Bizouard C. - ISBN 978-84-1302-092-1 Pages s. 3-10 Number of pages 7 s. Publication form Online - E Action Proceedings of the Journées 2017: Futhering our knowledge of Earth rotation Event date 25.09.2017 - 27.09.2017 VEvent location Alicante Country ES - Spain Event type WRD Language eng - English Country FR - France Keywords Earth’s orientation ; geomagnetic jerks ; geophysical excitations Subject RIV BN - Astronomy, Celestial Mechanics, Astrophysics OECD category Astronomy (including astrophysics,space science) Institutional support ASU-R - RVO:67985815 Annotation It is well known that the Earth’s orientation is affected, in addition to external torques caused by the Moon, Sun and planets, also by excitation by geophysical fluids (atmosphere, oceans, and hydrology). Only very recently it was noticed that the observed changes of the amplitud and phase of the free modes (Chandler wobble, Free Core Nutation) are correlated with the rapid changes of the second time derivative of geomagnetic field, so called geomagnetic jerks (GMJ). These events occur irregularly, in intervals of several years, and last typically several months. We use Brzezinski’s broad band Liouville equations (expressed both in terrestrial and celestial reference frames) to integrate numerically the changes of Earth’s orientation due to geophysical excitations. We use standard excitations by atmosphere and oceans (hydrology being neglected), and we also add GMJ effect, modeled as impulse-like functions centered at GMJ epochs. We are able to demonstrate that the agreement of the integrated Earth orientation with the observed values significantly improves when GMJ effect is considered. This approach enables us also to determine the parameters of the free modes (period, Q-factor) with improved accuracy. Workplace Astronomical Institute Contact Radka Svašková, bibl@asu.cas.cz, Tel.: 323 620 326 Year of Publishing 2021
Number of the records: 1