EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Effects of the observed Earth’s oblateness variation on precession-nutation: A first assessment

José M. Ferrándiz1, Alberto Escapa1,2, Tomás Baenas3, Santiago Belda4, and M. Isabel Vigo1
José M. Ferrándiz et al.
  • 1Universidad de Alicante, Space Geodesy Group, Applied Mathematics, EPS, ALICANTE, Spain (
  • 2Universidad de León, 2Dept. of Aerospace Engineering, León, Spain (
  • 3Centro Universitario de la Defensa, MDE- UPTC, San Javier, Murcia, Spain (
  • 4Universidad de Valencia, Valencia, Spain (

The current IAU2000 nutation theory considers the Earth’s dynamical ellipticity as a constant, whereas the IAU2006 precession theory uses a linear model for it. Apart from the problems of consistency between the two theories, whose full solution was proposed recently, the fundamental issue, namely whether the observed time variation of the Earth’s gravity field can affect the Earth’s rotation to a non-negligible extent or not, remains untreated.

This presentation is intended to share some preliminary results concerning precession and nutation. The variation of the Earth’s dynamical ellipticity is modelled from one of the time series providing the time-varying Stokes coefficients, and its effects on the longitude are computed following a new method introduced by the authors to that purpose. The found variations are above the accuracy goals of GGOS, the Global Geodetic Observing System of the International Association of Geodesy, adopted by its Joint Working Group on Improving theories and models of the Earth rotation (JWG ITMER).

How to cite: Ferrándiz, J. M., Escapa, A., Baenas, T., Belda, S., and Vigo, M. I.: Effects of the observed Earth’s oblateness variation on precession-nutation: A first assessment, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16509,, 2020