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| Titel |
Wavelet based directional analysis of the gravity field: evidence for large-scale undulations |
| VerfasserIn |
M. Hayn, I. Panet, M. Diament, M. Holschneider, M. Mandea, A. Davaille |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250064152
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| Zusammenfassung |
| In the eighties, the analysis of satellite altimetry data lead to the major
discovery of gravity lineations in the oceans, with wavelengths between 200 km
and 1400 km. While the existence of the 200 km scale undulations is widely accepted,
undulations at scales larger than 400 km are still a matter of debate.
In our work, we revisit the topic of the large scale geoid undulations over the
oceans in the light of the satellite gravity data provided by the GRACE mission,
considerably more precise than the altimetry data at wavelengths larger than 400 km.
First, we develop a dedicated method of directional Poisson wavelet analysis on
the sphere with significance testing, in order to detect and characterize
directional structures in geophysical data on the sphere at different spatial
scales. This method is particularly well-suited for potential field analysis.
We validate it on a series of synthetic tests, and then apply it to analyze
the gravity model EGM2008, as well as a bathymetry dataset independent from gravity.
Our analysis confirms the existence of gravity undulations at large scale in the oceans, with
characteristic scales between 600 and 2000 km. Their direction correlates
well with present-day plate motion over the Pacific ocean, where they are particularly
clear, and associated with a conjugate direction at 1500 km scale.
A major finding is that the 2000 km scale geoid undulations, which
has never been so clearly previously observed, dominate. We discuss these results in terms of geodynamic and mantle convection. |
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