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| Titel |
The potential of ground gravity measurements to validate GRACE data |
| VerfasserIn |
D. Crossley, J. Hinderer, M. Llubes, N. Florsch |
| 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 (2003-06-17), S.65-71 |
| Datensatznummer |
250000037
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| Publikation (Nr.) |
 copernicus.org/adgeo-1-65-2003.pdf |
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| Zusammenfassung |
New satellite missions are returning high precision,
time-varying, satellite measurements of the Earth’s
gravity field. The GRACE mission is now in its calibration/-
validation phase and first results of the gravity field solutions
are imminent. We consider here the possibility of external
validation using data from the superconducting gravimeters
in the European sub-array of the Global Geodynamics
Project (GGP) as ‘ground truth’ for comparison with
GRACE. This is a pilot study in which we use 14 months
of 1-hour data from the beginning of GGP (1 July 1997) to
30 August 1998, when the Potsdam instrument was relocated
to South Africa. There are 7 stations clustered in west central
Europe, and one station, Metsahovi in Finland. We remove
local tides, polar motion, local and global air pressure, and
instrument drift and then decimate to 6-hour samples. We
see large variations in the time series of 5–10µgal between
even some neighboring stations, but there are also common
features that correlate well over the 427-day period. The 8
stations are used to interpolate a minimum curvature (gridded)
surface that extends over the geographical region. This
surface shows time and spatial coherency at the level of 2–
4µgal over the first half of the data and 1–2µgal over the latter
half. The mean value of the surface clearly shows a rise in
European gravity of about 3µgal over the first 150 days and
a fairly constant value for the rest of the data. The accuracy
of this mean is estimated at 1µgal, which compares favorably
with GRACE predictions for wavelengths of 500 km or
less. Preliminary studies of hydrology loading over Western
Europe shows the difficulty of correlating the local hydrology,
which can be highly variable, with large-scale gravity
variations.
Key words. GRACE, satellite gravity, superconducting
gravimeter, GGP, ground truth |
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