Period and Q-factor of Free Core Nutation, based on different geophysical excitations and VLBI solutions

Title:

Period and Q-factor of Free Core Nutation, based on different geophysical excitations and VLBI solutions

Creator:

Jan Vondrák and Cyril Ron

Identifier:

https://cdk.lib.cas.cz/client/handle/uuid:ec7254c4-1bb3-49dd-956e-7f80aae526ad
uuid:ec7254c4-1bb3-49dd-956e-7f80aae526ad
issn:1214-9705
doi:10.13168/AGG.2020.0015

Subject:

geofyzika, geophysics, rotation of the Earth, geophysical excitations, geomagnetic jerks, VLBI, celestial pole offsets, free core nutation, 7, and 551

Type:

model:article and TEXT

Format:

print, bez média, and svazek

Description:

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). Brzeziński’s broad-band Liouville equations (Brzeziński, 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., Jan Vondrák and Cyril Ron., and Obsahuje bibliografii

Language:

English

Rights:

http://creativecommons.org/publicdomain/mark/1.0/
policy:public

Coverage:

207-215

Source:

Acta geodynamica et geomaterialia : | 2020 Volume:17 | Number:2 (198)

Harvested from:

CDK

Metadata only:

false