Computation and assessment of the fifth release of the GOCE-only space-wise solution
19/09/2016 | 16:30 | Session 1: Current and future satellite gravity missions
Author(s): Andrea Gatti, Mirko Reguzzoni, Federica Migliaccio and Fernando Sansò
Andrea Gatti, Mirko Reguzzoni, Federica Migliaccio and Fernando Sansò
The fifth release of the space-wise approach, as well as the ones of the direct and time-wise approaches, is based on the processing of the whole GOCE dataset, from November 2009 to October 2013. It consists in global grids of gravity gradients at 0.2°x0.2° spatial resolution and in a spherical harmonic model derived from these grids by a discretized quadrature formula and by a proper global regularization. Output products are distributed through the ESA website and the ICGEM service.
The main difference between the space-wise approach and the other two official methods is that the GOCE data acquired along the orbit are compressed onto global grids by applying collocation on local data patches, each of them with its own locally adapted signal covariance. In this way the filtering level is locally controlled, differently from the other solutions where a global regularization on spherical harmonic coefficients is applied.
The good quality of the space-wise products has been assessed by comparing them with other grid solutions (e.g. the ones computed in the framework of the STSE GOCE+ GeoExplore project) and with other spherical harmonic models (e.g. the ones by the direct and time-wise approaches). The latter comparison also indicates the weakness of the local collocation method to optimally estimate the low and medium degrees of the gravity field spectrum but, at the same time, its better capability to recover the highest degrees where the regularization strategy plays an important role.