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Titel |
Tidal Effects on GOCE Satellite Gravity Gradiometry |
VerfasserIn |
Z. C. Luo, G. Yang, B. Zhong, Y. L. 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 |
250025202
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Zusammenfassung |
ABSTRACT: The primary object of GOCE (Gravity field and steady-state Ocean Circulation
Explorer) is the determination of the global static gravity field with uttermost precision and
resolution, instead of its temporal variations. Hence, the effects of time-variation signals,
which include tidal effects and other temporal effects, should be taken into account prior to
the data reduction process. Direct astronomical tides, solid earth tides, ocean tides and
pole tide, which are the principal contributors for the tidal part, are selected for
simulation analysis. In this paper, their effects on the orbiting gravity gradiometry are
calculated on a sphere at the altitude of GOCE spacecraft with respect to the local
north-oriented reference frame, other than along the track of GOCE satellite, in order to
ascertain the impact at the global level. The spatial distributions of the tidal effects are
presented and the maximum and minimum values during an interval of 30 days are
estimated. Besides, the power spectral density is evaluated to characterize the tide
power signals and the influences are compared with the GOCE measurement error
to find out whether the GOCE satellite possesses the competence to sense these
impacts.
To correct the tidal effects on the GOCE gravity gradient, we calculate their action on the
gradiometer, which are the second order derivatives of the tidal generating potential from July
15, 2000 to August 14, 2000, with the interval of 30 minutes. Each calculation point locates
at the center of 1Ë Ã1Ë grid on a sphere at the height of 250 km, the average altitude of
GOCE satellite. We plot the spatial distribution of the gravity gradient corrections and find
out that, with time passing by, the direct astronomical tides and the solid earth tides move
from east to west systematically. The transfiguration of ocean tides is complicated and the
solid earth polar tide changes imperceptibly. The entire influence of the solid earth
tides is lower than that of the direct astronomical tides, and greater than that of the
ocean tides. The corrections for the pole tides are the smallest. By estimating the
maximum and minimum values of the influence temporally and spatially, the simulation
results demonstrate that the tides will affect the GOCE gradiometer signals at the
level from 10-3E to 10-4E. That is, the temporal tidal corrections are generally
below the GOCE gravity gradient error level. But the temporal signals cannot be
totally ignored because they may be systematic and consistent to the GOCE gravity
gradients.
Keywords: tidal effects, gravity gradient, GOCE
Acknowledgements: This research was jointly supported by the National Natural
Science Foundation of China (No.40874002), the National 863 Program of China (Project
No.2008AA12Z105), and the New Century Excellent Talents Plan of Ministry of Education,
China (NCET-07-0635). |
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