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Titel |
M2 tidal parameter modulation revealed by superconducting gravimeter time series |
VerfasserIn |
Bruno Meurers, Michel Van Camp, Olivier Francis, Vojtech Pálinkáš |
Konferenz |
EGU General Assembly 2016
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Medientyp |
Artikel
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Sprache |
en
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 18 (2016) |
Datensatznummer |
250125331
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Publikation (Nr.) |
EGU/EGU2016-4901.pdf |
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Zusammenfassung |
Analyzing consecutive and independent 1-yr data sets of 10 European superconducting
gravimeters (SG) reveals statistically significant temporal variations of M2 tidal parameters.
Both common short-term (< 2 yr) and long-term (> 2 yr) features are identified in all SG
time series but one. The averaged variations of the amplitude factor are about 0.2 per mille.
The path of load vector variations equivalent to the temporal changes of tidal parameters
suggests the presence of an 8.85 yr modulation (lunar perigee). The tidal waves having the
potential to modulate M2 with this period belong to the 3rd degree constituents. Their
amplitude factors turn out to be much closer to body tide model predictions than that of the
main 2nd degree M2, which indicates ocean loading for 3rd degree waves to be less
prominent than for 2nd degree waves within the M2 group. These two different
responses to the loading suggest that the observed long-term modulation is more
due to insufficient frequency resolution of limited time series rather than to time
variable loading. Presently, SG gravity time series are still too short to prove if time
variable loading processes are involved too as in case of the annual M2 modulation
known to appear for analysis intervals of less than 1 yr. The observed variations
provide an upper accuracy limit for Earth model validation and permit estimating the
temporal stability of SG scale factors and assessing the quality of gravity time series. |
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