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| Titel |
Geocenter motion from space geodesy. What precision can be expected from current estimations? |
| VerfasserIn |
X. Collilieux, L. Métivier, Z. Altamimi, J. Ray, T. van Dam, X. Wu |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250025624
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| Zusammenfassung |
| The net translations of the networks of stations that track satellites with respect to crust-based
secular terrestrial frames are expected to contain the signature of the geocenter
motion. This phenomenon is defined to be the motion of center of mass of the Earth
(CM) with respect to the center of figure of the solid Earth surface (CF), which is
normally realized by a specific network whose frame center is the center of network
(CN).
We specifically study here the translation time series derived from satellite laser
ranging technique (SLR) data and their non-linear variations. We show, using two
loading models derived from fluid data and a GPS displacement field inversion,
compared with SLR results, that the expected loading signal ranges between two to four
millimeters at the annual frequency depending of the component. Additionally, the
level of SLR translation bias due to SLR network size and distribution should be
reasonably at the level of one millimeter, mostly along X and Z components at the
annual frequency with a scatter of about 1.5 millimeters. These quantities should
consequently be analyzed with caution. We suggest some methods to cope with this
problem.
Assuming that random errors affect station positions uniformly, this problem partly relies on
how closely the center of network of stations approximates the center of figure of the Earth. It
is more critical for secular variations of the geocenter motion, related to station
velocities. It also relies on the capacity of the SLR data analysis and of an ITRF-like
combination to generate station velocity field expressed with respect to the CM. Based
on current ITRF networks and geometric considerations, we wish to evaluate the
long-term geocenter motion error that could be derived from the ITRF velocity
field. |
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