Excitation of the Earth’s Orientation by Geophysical fluids and Geomagnetic Jerks

Kód výsledku v IS VaVaI

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Výsledek na webu

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DOI - Digital Object Identifier

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Jazyk výsledku

angličtina

Název v původním jazyce

Excitation of the Earth’s Orientation by Geophysical fluids and Geomagnetic Jerks

Popis výsledku v původním jazyce

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.

Název v anglickém jazyce

Excitation of the Earth’s Orientation by Geophysical fluids and Geomagnetic Jerks

Popis výsledku anglicky

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.

Druh

D - Stať ve sborníku

CEP obor

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OECD FORD obor

10308 - Astronomy (including astrophysics,space science)

Projekt

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Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2020

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název statě ve sborníku

Proceedings of the Journées 2017: Futhering our knowledge of Earth rotation

ISBN

978-84-1302-092-1

ISSN

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e-ISSN

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Počet stran výsledku

7

Strana od-do

3-10

Název nakladatele

Observatoire de Paris

Místo vydání

Paris

Místo konání akce

Alicante

Datum konání akce

25. 9. 2017

Typ akce podle státní příslušnosti

WRD - Celosvětová akce

Kód UT WoS článku

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