Stability of period and quality factor of free core nutation

Title:

Stability of period and quality factor of free core nutation

Creator:

Jan Vondrák and Cyril Ron

Identifier:

https://cdk.lib.cas.cz/client/handle/uuid:88e6202a-a397-40c3-9f31-1e5e054b75fa
uuid:88e6202a-a397-40c3-9f31-1e5e054b75fa
issn:1214-9705

Subject:

Geologie. Meteorologie. Klimatologie, geodynamika, geodynamics, earth orientation, nutation, geophysical excitation, VLBI, 7, and 551

Type:

article, články, model:article, and TEXT

Format:

print, bez média, and svazek

Description:

In our study we find, from the analysis of VLBI observations, small quasi-periodic fluctuations of the period and quality factor of retrograde Free Core Nutation (FCN), ranging mainly between 429.8 to 430.8 days and 17000 to 21000, respectively. To this end, we use resonant effects in several dominant forced nutation terms to calculate the period and quality factor of FCN in running 6-year intervals. We also recently demonstrated that the atmospheric and oceanic excitations are capable of exciting FCN. Both amplitude and phase of the geophysically excited motion are consistent with the values observed by VLBI, in the interval of tens of years. The geophysical excitations are now numerically integrated, using Brzeziński’s broadband Liouville equations, and removed from the observed celestial pole offsets. The remaining part is then used to derive the period and quality factor of FCN in running intervals, and to study the temporal stability of these important Earth parameters. It is demonstrated that the observed quasi-periodic variations of both parameters are probably not caused by these geophysical excitations., Jan Vondrák and Cyril Ron., and Obsahuje bibliografii

Language:

English

Rights:

http://creativecommons.org/licenses/by-nc-sa/4.0/
policy:public

Source:

Acta geodynamica et geomaterialia : | 2009 Volume:6 | Number:3 (155)

Harvested from:

CDK

Metadata only:

false