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| Titel |
Influence of dynamical equatorial flattening and orientation of a triaxial core on prograde diurnal polar motion |
| VerfasserIn |
Rong Sun, WenBin Shen |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250131295
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| Publikation (Nr.) |
 EGU/EGU2016-11689.pdf |
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| Zusammenfassung |
| The noise floor of empirical models of diurnal Earth Rotation could reach as low as 1μas as
shown by several recent studies. In another aspect, the differences between these empirical
models with the theoretical model predictions given by IERS Convention (2010) for
certain diurnal frequencies are more than 10 μas (e.g. K1). The traxiality of the core
is ignored in the theoretical model given by IERS Convention (2010) because it
is highly uncertain. To explain the difference between the empirical model and
theoretical model, we consider the possible influence of a triaxial core. We use the
difference between empirical models and theoretical model predictions given by IERS
Convention (2010) as input to invert the traxiality parameter of the core. In the
inversion, we assume the ocean tide response obeys the admittance theory. So extra six
admittance parameters are introduced to model the difference between smooth responses
inferred from empirical models and that given by theoretical model predictions
from IERS Convention (2010). The results show that adding core triaxiality into
the theoretical model could narrow the difference between empirical model and
theoretical model at diurnal frequencies. The residual of amplitude becomes smaller.
For a set of tide components consisting of seven diurnal frequencies (Q1, O1, M1,
P1, K1, J1, Oo1), the root mean square of the residual of this set have decreased
from more than 10μas to 2∼3μas for most of the empirical models. As for the
dynamical equatorial flattening of the core, estimates inverted based on different
empirical models are consistent within standard deviation. The results also suggest
that the principal axes of the triaxial core does not coincidence with the principal
axes of the whole Earth. This study is supported by National 973 Project China
(grant No. 2013CB733305), NSFC (grant Nos. 41174011, 41210006, 41504019). |
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