GOCE: dealing with large attitude variations in the conceptual structure of the space-wise approach
Dr Mirko Reguzzoni(1), Prof Federica Migliaccio(1)
, Prof Fernando Sansò(1)
, and Dr Paolo Zatelli(2)
Politecnico di Milano,
Via Valleggio, 11,
(2) Università di Trento, Via Mesiano,77, 38050 Trento, Italy
The space-wise approach to the analysis of GOCE data utilizes a grid of
convenient “geographic” second order derivatives on a boundary sphere
at satellite altitude. These derivatives are to be predicted from
actually observed data, which include second derivatives along
instrumental axes; in fact the instrumental and geographic frames are
not perfectly aligned (e.g. the z-axis is not radial).
The prediction can be performed by collocation by exploiting the full
covariance (and cross-covariance) of the second derivatives tensors in
two arbitrarily rotated frames. This solution is being implemented by
UCPH and it has to work only with local data for the well-known
limitation in the numerical handling of collocation formula.
Since the “radial” component Trr is the most informative component, we
are particularly interested in the effect of the misalignment on the
prediction of Trr. In this respect Tzz is the most important
contributor because the z-axis is very close to the radial axis.
In the paper we present a study on the possibility of performing this
prediction by applying a Wiener filter along the orbit, exploiting the
full spatial covariance structure of T, as it has been recently done by
POLIMI, in a simpler context.
Keywords: ESA European
Space Agency - Agence spatiale europeenne,
observation de la terre, earth observation,
satellite remote sensing,
teledetection, geophysique, altimetrie, radar,
chimique atmospherique, geophysics, altimetry, radar,