New method for determining free core nutation parameters, considering geophysical effects

Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A_____%2F17%3A00478841" target="_blank" >RIV/67985815:_____/17:00478841 - isvavai.cz</a>
Result on the web
<a href="http://dx.doi.org/10.1051/0004-6361/201730635" target="_blank" >http://dx.doi.org/10.1051/0004-6361/201730635</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1051/0004-6361/201730635" target="_blank" >10.1051/0004-6361/201730635</a>

Result language
angličtina
Original language name
New method for determining free core nutation parameters, considering geophysical effects
Original language description
In addition to the torques exerted by the Moon, Sun, and planets, changes of precession-nutation are known to be caused also by geophysical excitations. Recently studies suggest that geomagnetic jerks (GMJ) might be associated with sudden changes of phase and amplitude of free core nutation. We showed that using atmospheric and oceanic excitations with those by GMJ improves substantially the agreement with observed celestial pole offsets. Traditionally, the period T-f and quality factor Q(f) of the free core nutation (FCN) are derived from VLBI-based celestial pole offsets (CPO). Either direct analysis of the observed CPO, or indirect method using resonant effects of nutation terms with frequencies close to FCN, are used. The latter method is usually preferred, since it yields more accurate results. Our aim is to combine both approaches to better derive FCN parameters. The results, based on the CPO data in the interval 1986.0-2016.0 and excitations with three different models, are presented. We demonstrate that better results are obtained if the influence of additional excitations at GMJ epochs is added to excitations by the atmosphere and oceans. Our preferred values are T-f = 430.28 +/- 0.04 mean solar days and Q(f) = 19 500 +/- 200.n
Czech name
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Czech description
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Type
J<sub>imp</sub> - Article in a specialist periodical, which is included in the Web of Science database
CEP classification
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OECD FORD branch
10308 - Astronomy (including astrophysics,space science)

Project
<a href="/en/project/GA13-15943S" target="_blank" >GA13-15943S: The geophysical excitations in the motion of Earth's spin axis</a><br>
Continuities
P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Publication year
2017
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

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