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| Titel |
Clock measurements to improve the geopotential determination |
| VerfasserIn |
Guillaume Lion, Isabelle Panet, Pacôme Delva, Peter Wolf, Sébastien Bize, Christine Guerlin |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250151256
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| Publikation (Nr.) |
 EGU/EGU2017-15819.pdf |
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| Zusammenfassung |
| Comparisons between optical clocks with an accuracy and stability approaching
the 10−18 in term of relative frequency shift are opening new perspectives for the
direct determination of geopotential at a centimeter-level accuracy in geoid height.
However, so far detailed quantitative estimates of the possible improvement in
geoid determination when adding such clock measurements to existing data are
lacking.
In this context, the present work aims at evaluating the contribution of this new kind of
direct measurements in determining the geopotential at high spatial resolution (10 km). We
consider the Massif Central area, marked by smooth, moderate altitude mountains and
volcanic plateaus leading to variations of the gravitational field over a range of spatial scales.
In such type of region, the scarcity of gravity data is an important limitation in deriving
accurate high resolution geopotential models.
We summarize our methodology to assess the contribution of clock data in
the geopotential recovery, in combination with ground gravity measurements. We
sample synthetic gravity and disturbing potential data from a spherical harmonics
geopotential model, and a topography model, up to 10 km resolution; we also build a
potential control grid. From the synthetic data, we estimate the disturbing potential by
least-squares collocation. Finally, we assess the quality of the reconstructed potential by
comparing it to that of the control grid. We show that adding only a few clock data
reduces the reconstruction bias significantly and improves the standard deviation by a
factor 3. We discuss the role of different parameters, such as the effect of the data
coverage and data quality on these results, the trade-off between the measurement
noise level and the number of data, and the optimization of the clock data network. |
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