Period and Q-Factor of Free Core Nutation, Based on Different Geophysical Excitations and VLBI Solutions

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A_____%2F20%3A00537141" target="_blank" >RIV/67985815:_____/20:00537141 - isvavai.cz</a>

Výsledek na webu

<a href="http://hdl.handle.net/11104/0314892" target="_blank" >http://hdl.handle.net/11104/0314892</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.13168/AGG.2020.0015" target="_blank" >10.13168/AGG.2020.0015</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Period and Q-Factor of Free Core Nutation, Based on Different Geophysical Excitations and VLBI Solutions

Popis výsledku v původním jazyce

Three variants of geophysical excitations and seven different VLBI solutions of celestial pole offsets (CPO) are used to determine period and Q-factor of Free Core Nutation (FCN). Brzezinski's broad-band Liouville equations (Brzezinski, 1994) are numerically integrated to derive geophysical effects in nutation in time domain. Possible effect of geomagnetic jerks (GMJ) is also considered. Best-fitting values of FCN parameters are estimated by least-squares fit to observed CPO, corrected for the differences between the FCN parameters used in IAU 2000 model of nutation and newly estimated ones, MHB transfer function is used to compute these corrections. It is demonstrated that different VLBI solutions lead to FCN parameters that agree on the level of their formal uncertainties, but different models of geophysical excitations change the results more significantly. Using GMJ excitations always brings improvement of the fit between integrated and observed CPO. The obtained results show that the best fit is achieved when only GMJ excitations are used. Our conclusion is that GMJ are very probably more important for exciting FCN than the atmosphere and oceans. Empirical Sun-synchronous correction, introduced in the present IAU 2000 nutation model, cannot be explained by diurnal atmospheric tidal effects.

Název v anglickém jazyce

Period and Q-Factor of Free Core Nutation, Based on Different Geophysical Excitations and VLBI Solutions

Popis výsledku anglicky

Three variants of geophysical excitations and seven different VLBI solutions of celestial pole offsets (CPO) are used to determine period and Q-factor of Free Core Nutation (FCN). Brzezinski's broad-band Liouville equations (Brzezinski, 1994) are numerically integrated to derive geophysical effects in nutation in time domain. Possible effect of geomagnetic jerks (GMJ) is also considered. Best-fitting values of FCN parameters are estimated by least-squares fit to observed CPO, corrected for the differences between the FCN parameters used in IAU 2000 model of nutation and newly estimated ones, MHB transfer function is used to compute these corrections. It is demonstrated that different VLBI solutions lead to FCN parameters that agree on the level of their formal uncertainties, but different models of geophysical excitations change the results more significantly. Using GMJ excitations always brings improvement of the fit between integrated and observed CPO. The obtained results show that the best fit is achieved when only GMJ excitations are used. Our conclusion is that GMJ are very probably more important for exciting FCN than the atmosphere and oceans. Empirical Sun-synchronous correction, introduced in the present IAU 2000 nutation model, cannot be explained by diurnal atmospheric tidal effects.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10308 - Astronomy (including astrophysics,space science)

Projekt

—

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 periodika

Acta Geodynamica et Geomaterialia

ISSN

2336-4351

e-ISSN

—

Svazek periodika

17

Číslo periodika v rámci svazku

2

Stát vydavatele periodika

CZ - Česká republika

Počet stran výsledku

9

Strana od-do

207-215

Kód UT WoS článku

000546750100006

EID výsledku v databázi Scopus

2-s2.0-85090734595