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| Titel |
Gravity Field Determination at AIUB: From CHAMP and GRACE to GOCE |
| VerfasserIn |
Gerhard Beutler, Adrian Jaeggi, Ulrich Meyer, Lars Prange, Heike Bock, Rolf Dach, Leos Mervart |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250051042
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| Zusammenfassung |
| Gravity field recovery at the Astronomical Institute of the University of Bern (AIUB) is
rigorously treated as an extended orbit determination problem, which avoids the
introduction of any a priori gravity field information from the CHAMP-, GRACE-, or
GOCE-era. The so-called Celestial Mechanics Approach is applied to GPS high-low
satellite-to-satellite tracking (hl-SST) data of low Earth orbiters (LEOs), via the use of
previously established kinematic LEO positions, to K-band low-low satellite-to-satellite
tracking (ll-SST) data of the GRACE mission, and to gradiometer data of the GOCE mission.
Mathematical or empirical covariances of all observations may be taken into account on
request.
We use CHAMP and GOCE hl-SST data to fully exploit the long wavelength part of the
Earth’s gravity field. We validate the derived gravity field models by performing
LAGEOS orbit determination using Satellite Laser Ranging (SLR) measurements
and demonstrate that GPS hl-SST gives access to high-quality estimates of the
lowest degree coefficients. We also assess the contribution of GPS hl-SST to the
recovery of time variable gravity signals and show that large-scale variations may be
captured.
We present the new release AIUB-GRACE03S based on 7 years of K-band ll-SST and
GPS hl-SST data, consisting of a static gravity field resolved up to degree 160 and a series of
monthly gravity field models resolved up to degree 60. We compare the AIUB-GRACE03S
release with results from other research groups and assess the differences between a
simultaneous estimation of annual, semi-annual and trend signals with the static field and the
estimation of a static field only.
As opposed to the commonly applied filtering techniques for GOCE gravity field recovery
based on gradiometer data, empirical parameters are set up in addition to the gravity field
coefficients to absorb the non-physical part of the gradiometer measurements. First results of
this appraoch are presented, which is by construction independent of the a priori gravity field
information.
The Celestial Mechanics Approach was generalized to take empirically derived
covariance information into account, e.g., derived from the analysis of residuals. We study the
impact of empirical covariance information on the GOCE gradiometer solutions and on the
monthly GRACE solutions. We discuss in particular the important issue, whether information
may be introduced from the gravity field model underlying the residuals used for the
establishment of the empirical covariances. |
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