Quality Assessment of GOCE Gradients

authored by: Focke Jarecki, Karen Insa Wolf, Heiner Denker, Jürgen Müller
Abstract: To meet the accuracy requirements of the GOCE mission, the gradiometer has to be calibrated and validated internally as well as externally. An internal quality assessment of the observed GOCE data is possible by comparisons of observations at the same satellite position, i.e. at satellite track cross-overs. Due to the orbit characteristics of the mission, satellite ground track cross-overs have to be used instead of identical repeat positions. Therefore, an appropriate reduction concept has to be applied to consider the differences caused by different satellite altitudes and orientations. It is shown here, that present global gravity field models meet the accuracy and resolution requirements for the reduction concept, and hence for the relative validation of GOCE gradients. For an external calibration or validation based on regional data sets, terrestrial gravity anomalies are upward continued to gravitational gradients at GOCE altitude. The computations are done with synthetic data in a closed-loop simulation. Two upward continuation methods are considered, namely least-squares collocation and integral formulas based on the spectral combination technique. Both methods are described and the results are compared numerically with the ground-truth data. Finally, the results of a regional calibration experiment with simulated noisy GOCE gradients are described.
Organisation(s): Institute of Geodesy
Type: Contribution to book/anthology
Pages: 271-285
No. of pages: 15
Publication date: 2006
Publication status: Published
Peer reviewed: Yes
ASJC Scopus subject areas: General Environmental Science, General Earth and Planetary Sciences
Electronic version(s): https://doi.org/10.1007/3-540-29522-4_19 (Access: Closed)
: Details in the research portal "Research@Leibniz University"

BibTeX

@inbook{b5a24c36dba64a12b08cb8a79f0ffa8e,
title = "Quality Assessment of GOCE Gradients",
abstract = "To meet the accuracy requirements of the GOCE mission, the gradiometer has to be calibrated and validated internally as well as externally. An internal quality assessment of the observed GOCE data is possible by comparisons of observations at the same satellite position, i.e. at satellite track cross-overs. Due to the orbit characteristics of the mission, satellite ground track cross-overs have to be used instead of identical repeat positions. Therefore, an appropriate reduction concept has to be applied to consider the differences caused by different satellite altitudes and orientations. It is shown here, that present global gravity field models meet the accuracy and resolution requirements for the reduction concept, and hence for the relative validation of GOCE gradients. For an external calibration or validation based on regional data sets, terrestrial gravity anomalies are upward continued to gravitational gradients at GOCE altitude. The computations are done with synthetic data in a closed-loop simulation. Two upward continuation methods are considered, namely least-squares collocation and integral formulas based on the spectral combination technique. Both methods are described and the results are compared numerically with the ground-truth data. Finally, the results of a regional calibration experiment with simulated noisy GOCE gradients are described.",
keywords = "calibration, cross-overs, upward continuation, validation",
author = "Focke Jarecki and Wolf, {Karen Insa} and Heiner Denker and J{\"u}rgen M{\"u}ller",
note = "Thanks go to K.-H. Ilk and IAG-SC7 for making the GOCE test data available and to C.C. Tscherning for providing his covariance computation routines. This is publication no. GEOTECH-158 of the programme GEOTECHNO- LOGIEN of BMBF and DFG, Grant 03F0329D",
year = "2006",
doi = "10.1007/3-540-29522-4_19",
language = "English",
isbn = "3540295208",
pages = "271--285",
booktitle = "Observation of the Earth System from Space",
publisher = "Springer Berlin Heidelberg",
}