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

Kód výsledku v 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>

Výsledek na webu

<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>

Jazyk výsledku

angličtina

Název v původním jazyce

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

Popis výsledku v původním jazyce

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

Název v anglickém jazyce

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

Popis výsledku anglicky

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

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10308 - Astronomy (including astrophysics,space science)

Projekt

<a href="/cs/project/GA13-15943S" target="_blank" >GA13-15943S: Geofyzikální excitace v pohybu rotační osy Země</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2017

Kód důvěrnosti údajů

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

Název periodika

Astronomy & Astrophysics

ISSN

1432-0746

e-ISSN

—

Svazek periodika

604

Číslo periodika v rámci svazku

August

Stát vydavatele periodika

FR - Francouzská republika

Počet stran výsledku

7

Strana od-do

"A56/1"-"A56/7"

Kód UT WoS článku

000408480100087

EID výsledku v databázi Scopus

2-s2.0-85027021329