HR: 0800h
AN: G41C-0367 [Abstracts]
TI: Estimation of Earth Interior Parameters Based on the Nutation Obsservations in Time Series
AU: * Koot, L
EM: laurence.koot@oma.be
AF: Royal Observatory of Belgium, avenue circulaire 3, Brussels, B-1180
Belgium
AU: de Viron, O
EM: deviron@ipgp.jussieu.fr
AF: Royal Observatory of Belgium, avenue circulaire 3, Brussels, B-1180
Belgium
AU: de Viron, O
EM: deviron@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, Laboratoire de Gravimetrie et de Geodynamique, Place Jussieu 4,
Paris, F-75252
France
AU: Dehant, V
EM: veronique.dehant@oma.be
AF: Royal Observatory of Belgium, avenue circulaire 3, Brussels, B-1180
Belgium
AB:
The nutation response of the non-rigid Earth to the gravitational forcing by the Moon, the Sun, and the planets has been
modeled by Mathews et al. 2002 (MHB2000 model). This model is semi-analytic and depends on some unknown Earth interior
parameters, of which the numerical values are adjusted on the nutation data, in order to have a model which fits the
observations as well as possible. As the external forcing is mainly periodic, nutation observations are first transformed
into a series of amplitudes and phases, at the main relevant frequencies, to which the internal parameters are adjusted. We
have developed a nutation model similar to MHB2000, but we choose to work with time series rather than frequency series to
adjust the Earth interior parameters. The adjustment is done using a Bayesian (or stochastic) inversion method. This direct
estimation allows to avoid the extraction of amplitudes and phases of the main frequencies from the nutation data, to account
for the time variable quality of the nutation data, and to estimate the precession and obliquity rate consistently with the
other geophysical parameters. In the future, it will allow us to include the response of the Earth to non-periodic forcing in
the nutation model (such as, for instance, atmospheric effects).
DE: 1212 Earth's interior: composition and state (7207, 7208, 8105, 8124)
DE: 1229 Reference systems
DE: 1239 Earth rotation variations
SC: Geodesy [G]
MN: Fall Meeting 2005