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The GOCE User Toolbox

Jérôme Benveniste(1) and Per Knudsen & the GUTS Team(2)

(1) ESA, via Galieo Galilei, 00044 Frascati, Italy
(2) Danish National Space Center, Juliane Maries Vej 30, DK-2100 København Ø, Denmark

Abstract

Data from the ESA GOCE mission are of fundamental importance to the geodesy, solid Earth and oceanographic community. It is expected that in conjunction with altimetric observations, gravity data from the ESA GOCE Mission will - for the first time in history - allow access to the absolute ocean dynamic surface topography and to compute the absolute ocean surface geostrophic currents at spatial scales down to about 100 km. Despite their importance for oceanographic studies, the processing and analysis of gravity mission data has proven to be complicated to the point that the lack of proper processing software is hampering progress in the use of those data. Success in the exploitation of Spaceborne Gravity data therefore seems to depend fundamentally on the proper knowledge of several steps of the detailed gravity data processing procedure in terms of spherical harmonics, their implicit consistent normalization factors, filtering and error data, among others. To facilitate the easy use of GOCE products for geodesists, solid Earth scientitsts, oceanographers and to support the needs of specific applications, the development of a user toolbox (GOCE user toolbox study = GUTS) was identified as an urgent step at the Second International GOCE User Workshop.

Such a toolbox is required to guarantee optimal use of the existing and future gravity data acquired from GRACE and GOCE. In particular it is recognized and accepted that software packages are required that allow the gravity field data, in conjunction and consistent with any other auxiliary data sets, to be pre-processed by users not intimately familiar with gravity field processing procedure, for scientific application, both regionally and globally.

The final Level 2 products consist of: the precise orbit of GOCE, the gravity field in terms of spherical harmonic coefficients, the corrected, calibrated and geo-located gravity gradients, a map of the gravity anomalies and a map of the geoid. This effort will be an essential element in the entire GOCE data stream. However, no ocean circulation products are planned to be delivered as Level-2 products so that a strong need exists for GUTS to deliver oceanographers with additional information and tools that can turn the Level 2 products into application-dependent fields by further processing the GOCE Level-2 geoid and merging it with Radar Altimetry and other auxiliary data.

Among the fields that are important is the geoid error covariance function. For many applications it is required in geographic coordinates or at specific locations. The toolbox therefore needs to perform this and other extra functions that are essential for using the GOCE geoid fields efficiently and for testing it in geoid validation studied.

The GUTS working group is an open group, gathering the European Scientists around a study aimed at writing the specification of the GOCE User Toolbox (GUT), after a user requirement and algorithm trade-off study.

 

Workshop presentation

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, atmospheric chemistry