HR: 0800h
AN: IN21C-1194 INVITED     [Abstracts]
TI: Modeling the Earth's magnetic field using a modular approach
AU: * Maus, S
EM: stefan.maus@noaa.gov
AF: CIRES, University of Colorado, NOAA/NGDC E/GC1 325 Broadway, Boulder, CO 80305 United States
AB: Three ongoing satellite missions and about 200 globally distributed observatories provide highly accurate measurements of the Earth's magnetic field. The geomagnetic field is generated by various electric current systems, plus the magnetization of minerals in the crust. Its source regions range from the Earth's metallic core out to the magnetosphere. The magnetic field is a key geophysical observable of the Earth system. Its variety of fairly independent sources motivates the use of a modular approach in representing the field. The primary modules discussed here are the contributions from the core dynamo, electric currents induced by time-varying external fields in the conducting mantle and oceans, crustal magnetization, motion-induced electric currents in the oceans, and ionospheric, magnetospheric and field-aligned coupling currents. Each module consists of a set of parameters which either describes the source currents or directly represents the magnetic field signal of the particular phenomenon. In principle, the module parameters can be co-estimated from the observed magnetic field in a single, grand inversion. However, since the various phenomena differ strongly in amplitude, it is often advantageous to select an appropriate data set for a particular module and estimate its parameters separately. Geomagnetic phenomena are usually part of larger geophysical processes and therefore can benefit from other Earth models. In particular, our motional induction module is based on ocean velocity vectors from the TPXO tidal ocean flow model and the ionospheric current module uses ion densities from the International Reference Ionosphere (IRI).
DE: 1532 Reference fields: regional, global
DE: 1541 Satellite magnetics: main field, crustal field, external field
DE: 1545 Spatial variations: all harmonics and anomalies
DE: 1560 Time variations: secular and longer
SC: Earth and Space Science Informatics [IN]
MN: Fall Meeting 2005