HR: 0800h
AN: GP31A-0070 [Abstracts]
TI: Time-Domain Approach to Geomagnetic Induction Based
on Joint Use of Surface and Satellite Data
AU: * Velímský, J
EM: jakub.velimsky@mff.cuni.cz
AF: Charles University in Prague,
Faculty of Mathematics and Physics,
Department of Geophysics, V Holesovickach 2, Prague, 18000
Czech Republic
AU: Martinec, Z
EM: zdenek@gfz-potsdam.de
AF: Charles University in Prague,
Faculty of Mathematics and Physics,
Department of Geophysics, V Holesovickach 2, Prague, 18000
Czech Republic
AU: Martinec, Z
EM: zdenek@gfz-potsdam.de
AF: GeoForschungsZentrum Potsdam
Section 1.3, Telegrafenberg, Potsdam, D-14473
Germany
AB:
Availability of high precision data from satellite-borne magnetometers has recently motivated rapid development of effective
methods to address the forward geomagnetic induction problem in heterogeneous Earth. We present a modification of the
time-domain, spherical harmonic-finite element approach (Velímský and Martinec, 2005) that is based on joint use of
vector magnetic field measurements from satellites and surface observatories.
We use a physical model that consists of a spherical Earth with heterogeneous conductivity distribution surrounded
sequentially by
1) an insulating atmosphere;
2) ionosphere approximated by an infinitesimally thin spherical sheet of horizontal currents;
3) another insulating layer where satellite data are acquired; and
4) a distant current system in the magnetosphere.
Gaussian spherical harmonic analysis performed in both insulating layers and continuity of the vertical magnetic field across
the ionosphere allow us to parametrize the magnetic field outside the Earth by three sets of spherical harmonic
coefficients. These correspond respectively to current systems in the magnetosphere, in the ionosphere and in the solid
Earth. Two of these sets (or any two independent linear combinations of them) can be imposed in the forward formulation as
the boundary condition leaving the third set (or the remaining independent linear combination) for misfit evaluation of the
conductivity model.
Such a general forward approach allows to formulate the inverse problem using various combinations of a-priori models of
magnetospheric and ionospheric currents and measurements of vertical and horizontal magnetic field components on the surface
and in the space.
DE: 1515 Geomagnetic induction
DE: 1541 Satellite magnetics: main field, crustal field, external field
SC: Geomagnetism and Paleomagnetism [GP]
MN: Fall Meeting 2005