HR: 10:55h
AN: IN22A-03 INVITED     [Abstracts]
TI: Modeling the crustal magnetic field on the sphere by means of R-SCHA
AU: * THEBAULT, E
EM: erwan.thebault@gfz-potsdam.de
AF: GeoForschungsZentrum, Telegrafenberg, Potsdam, 14473 Germany
AB: Uneven data distribution around the Earth and the slow rate of convergence of spherical harmonics are both limiting factors for producing very high resolution maps of the geomagnetic field. These limitations have a particularly detrimental effect when considering ground-based and satellite data together. In practice, we therefore lack a mathematical tool in order to combine all the wavelengths of the magnetic. A possible alternative to the spherical harmonics is to consider the magnetic field at regional scale only and build up a new basis of functions. A powerful way to achieve this goal is to solve a Boundary Value Problem (BVP) in a closed domain. The Revised Spherical Cap Harmonic Analysis (R-SCHA) is a regional modeling technique that aims to represent the magnetic field at a regional scale from ground to satellite altitudes. The properties of R-SCHA will be illustrated on a set of perfect synthetic data in order to investigate what kind of information this technique is able or unable to convey. Then, using four years of CHAMP satellite data, a lithospheric model is computed at 400 km altitude over the entire sphere by stitching together a dense coverage of regional models. The transformation between these regional models and the spherical harmonics will also be discussed. Apart from accounting for regionally varying noise levels, the proposed technique is also well suited to deal with incomplete data coverage issues when combining satellite with near surface data. A few examples obtained including aeromagnetic, ground-based and satellite data in a joint inversion process over Europe will therefore be presented and analysed.
DE: 1517 Magnetic anomalies: modeling and interpretation
SC: Earth and Space Science Informatics [IN]
MN: Fall Meeting 2005