Computation of calibration gradients and methods for in-orbit validation of gradiometric GOCE data

authored by: J. Müller, H. Denker, F. Jarecki, K. I. Wolf
Abstract: The accuracy planned for GOCE gravity gradiometry requires special independent concepts for calibration and validation of the measured gravitational gradients. Although the gradiometer will be calibrated internally on ground (pre-flight) and prior to the measurement phase itself in orbit (in-flight), further external calibration, e.g., by the use of terrestrial gravity data, is obligatory to establish the relationship of the measurements to the Earth's gravitational field at the required accuracy level. To meet the accuracy of the satellite data, a region with well known gravity field parameters has to be selected for calibration. The Institut für Erdmessung at the University of Hanover has collected a data set of 5′ by 5′ gridded gravity anomalies in Central Europe. From these terrestrial gravity anomalies, gravitational gradients at GOCE altitude are computed as reference for calibration and validation purposes. The upward continuation of the gravity anomalies to the calibration gradients is carried out by two methods, namely least-squares collocation and integral formulas. Results of both methods are compared and analysed. Even without the availability of independent data, some conclusions on the quality and consistency of the observed GOCE data can be drawn by comparing measurements in the same satellite position, i.e. in satellite track cross-overs. Unfortunately, due to the orbit characteristics of the mission, one has to take into account satellite ground track cross-overs instead of identical repeat positions. Therefore, a 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 of the reduction concept.
Organisation(s): Institute of Geodesy
Type: Conference article
Journal: European Space Agency, (Special Publication) ESA SP
Pages: 111-118
No. of pages: 8
ISSN: 0379-6566
Publication date: 01.12.2004
Publication status: Published
Peer reviewed: Yes
ASJC Scopus subject areas: Aerospace Engineering, Space and Planetary Science
: Details in the research portal "Research@Leibniz University"

BibTeX

@article{0b48830f0feb45c09c5f5988008c9a8c,
title = "Computation of calibration gradients and methods for in-orbit validation of gradiometric GOCE data",
abstract = "The accuracy planned for GOCE gravity gradiometry requires special independent concepts for calibration and validation of the measured gravitational gradients. Although the gradiometer will be calibrated internally on ground (pre-flight) and prior to the measurement phase itself in orbit (in-flight), further external calibration, e.g., by the use of terrestrial gravity data, is obligatory to establish the relationship of the measurements to the Earth's gravitational field at the required accuracy level. To meet the accuracy of the satellite data, a region with well known gravity field parameters has to be selected for calibration. The Institut f{\"u}r Erdmessung at the University of Hanover has collected a data set of 5′ by 5′ gridded gravity anomalies in Central Europe. From these terrestrial gravity anomalies, gravitational gradients at GOCE altitude are computed as reference for calibration and validation purposes. The upward continuation of the gravity anomalies to the calibration gradients is carried out by two methods, namely least-squares collocation and integral formulas. Results of both methods are compared and analysed. Even without the availability of independent data, some conclusions on the quality and consistency of the observed GOCE data can be drawn by comparing measurements in the same satellite position, i.e. in satellite track cross-overs. Unfortunately, due to the orbit characteristics of the mission, one has to take into account satellite ground track cross-overs instead of identical repeat positions. Therefore, a 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 of the reduction concept.",
author = "J. M{\"u}ller and H. Denker and F. Jarecki and Wolf, {K. I.}",
year = "2004",
month = dec,
day = "1",
language = "English",
pages = "111--118",
journal = "European Space Agency, (Special Publication) ESA SP",
issn = "0379-6566",
publisher = "European Space Agency",
number = "569",
note = "Second International GOCE User Workshop: GOCE, The Geoid and Oceanography ; Conference date: 08-03-2004 Through 10-03-2004",
}