HR: 1340h
AN: IN23A-1203    [Abstracts]
TI: Modelling and Analyzing Potential Fields Using Poisson Multipole Wavelets
AU: Jamet, O
EM: jamet@ensg.ign.fr
AF: Laboratoire de Recherche en Géodésie, Institut Géographique National, 6/8, avenue Blaise Pascal - ENSG - Champs sur Marne, Marne la Vallée, 77455 France, Metropolitan
AU: * Panet, I
EM: panet@ipgp.jussieu.fr
AF: Laboratoire de Recherche en Géodésie, Institut Géographique National, 6/8, avenue Blaise Pascal - ENSG - Champs sur Marne, Marne la Vallée, 77455 France, Metropolitan
AU: * Panet, I
EM: panet@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, case 89, 4, place Jussieu, Paris, 75252 France, Metropolitan
AU: Chambodut, A
EM: chambodu@math.uni-potsdam.de
AF: Department of Applied Mathematics, University of Potsdam, Am Neuen Palais, 10, Potsdam, 14469 Germany
AU: Holschneider, M
EM: hols@math.uni-potsdam.de
AF: Department of Applied Mathematics, University of Potsdam, Am Neuen Palais, 10, Potsdam, 14469 Germany
AU: Diament, M
EM: diament@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, case 89, 4, place Jussieu, Paris, 75252 France, Metropolitan
AB: Modelling and analyzing geopotential fields is an efficient way to study the properties of planets interiors and changes of their near environment. As soon as large areas are considered, one has to work on a sphere. For instance, when dealing with satellite data, sphericity has to be taken into account, especially for small planets or satellites like Mars or the Moon. The spherical harmonics expansion is thus widely used, but drawbacks appear as soon as the data distribution is not regular or if the modelled area does not cover the whole sphere.
To overcome these drawbacks, we developed a wavelet-based representation of potential fields on the sphere. We chose to use the Poisson multipole wavelets (Holschneider et al. , 2003) which allow fast calculations. The discrete wavelet model is computed by a regularized least-square inversion. We tested different regularizations for gravity and magnetic field modelling. We compute the wavelet model following an iterative procedure. We first compute the large-scale components, and then progressively refine the model in an area of interest through an iterative procedure. We validated our method on synthetic tests (Chambodut et al., 2005) and as an example, we derive new gravity and magnetic models in the South Central Pacific area, based on satellite gravity and magnetic data.
Moreover, we show that thanks to the properties of the Poisson multipole wavelets, a continuous analysis of the models can easily be derived and related to the internal densities/magnetization distribution. Such an analysis is very useful to underline geophysical features in the fields at varying spatial scales. It allowed us to highlight new structures in the fields, bringing thus new constraints for the understanding of the geodynamic evolution of the considered area.
DE: 1214 Geopotential theory and determination (0903)
DE: 1219 Gravity anomalies and Earth structure (0920, 7205, 7240)
DE: 1541 Satellite magnetics: main field, crustal field, external field
DE: 3037 Oceanic hotspots and intraplate volcanism
DE: 3280 Wavelet transform (3255, 4455)
SC: Earth and Space Science Informatics [IN]
MN: Fall Meeting 2005