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| Titel |
From the time-wise to space-wise GOCE observables |
| VerfasserIn |
M. Reguzzoni |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7340
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| Digitales Dokument |
URL |
| Erschienen |
In: G1. The new gravity field mission (CHAMP, GRACE, GOCE): from measurements to geophysical interpretation ; Nr. 1 (2003-07-18), S.137-142 |
| Datensatznummer |
250000048
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| Publikation (Nr.) |
 copernicus.org/adgeo-1-137-2003.pdf |
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| Zusammenfassung |
The observables of the GOCE three-axis gradiometer
are taken in time, along the orbit and, in the timewise
proposal, filtered to stay in the measurement bandwidth,
i.e. in the frequency interval between 0.005 and 0.1Hz. As
a consequence, the resulting “observable" is a convolution
of the original data stream with a time-wise weighting kernel.
In other words, we cannot assume that the observations
are point-wise evaluations of any function and so, in a spacewise
approach, any averaging or interpolating operation to
obtain gridded spatial data has little sense.
The problem is therefore to model correctly the observational
functionals, including the correlation along the orbit.
This can be done by exploiting theWiener filter theory, using
the prior knowledge of a geopotential model and the power
spectral density (PSD) of the measurement error.
A numerical simulation from the EGM96 model (degrees
between 50 and 300) is performed, showing that the
along track Wiener filter produces Trr spatialized observables
with an error standard deviation of the order of 5 mE.
A covariance function of the estimation error is also provided
by the Wiener filter theory. The use of these filtered
observables in a space-wise approach allows for the reconstruction
of the gravity field in terms of spherical harmonics
up to degree 200.
Key words. Satellite gradiometry, space-wise approach,
measurement bandwidth, Wiener filter |
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