HR: 0800h
AN: GP31A-0827    [Abstracts]
TI: A new proposal for Spherical Cap Harmonic modeling and its application on various geomagnetic data.
AU: * THEBAULT, E
EM: Erwan.Thebault@gfz-potsdam.de
AF: GFZ, Telegrafenberg, POTSDAM, 14473 Germany
AU: SCHOTT, J
EM: JeanJacques.schott@eost.u-strasbg.fr
AF: EOST, 5, rue rene Descartes, STRASBOURG, 67000 France
AU: MANDEA, M
EM: mioara@ipgp.jussieu.fr
AF: IPGP, 4, place Jussieu, PARIS, 75252 France
AU: MAUS, S
EM: Stefan.Maus@noaa.gov
AF: NGDC, NOAA E/GC1 325 Broadway , BOULDER, CO 80305-3328 United States
AB: We recently proposed a new method for regional modeling of potential fields. Based on the solution of Laplace's equation in a conical region associated with particular boundary conditions, our method utilizes new mathematical functions able to represent faithfully the spatial variations of potential fields. We first refine our previous boundary value problem in order that the solutions satisfy the physical properties of a geomagnetic field and in order to have fully orthogonal basis functions inside the region under study. To outline the relevance of this new formalism, we tackle here two kinds of inverse problems using this novel method. First, by joint inversion, we derive a regional model over a small region such as France, by processing simultaneously aero-magnetic, repeat station and CHAMP satellite data. We also discuss the consistency of the predicted magnetic field values with geological features and existing magnetic maps of this region. Then, using four years of CHAMP vectorial data, we try to compute over the entire sphere a lithospheric model at 400km by stitching together different local models obtained in adjacent regions. These two results allow us firstly to highlight the continuity between this local modeling technique and that of the Spherical Harmonics, and secondly to outline the importance of regional modeling to the knowledge of the geomagnetic field at short and medium spatial wavelengths.
DE: 1517 Magnetic anomaly modeling
DE: 1532 Reference fields (regional, global)
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2004 AGU Fall Meeting