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GEOPHYSICAL RESEARCH LETTERS, VOL. 33, L18301, doi:10.1029/2006GL027083, 2006

A global model of mantle conductivity derived from 5 years of CHAMP, Ørsted, and SAC-C magnetic data

Alexei Kuvshinov

Danish National Space Center, Copenhagen, Denmark


Nils Olsen

Danish National Space Center, Copenhagen, Denmark


Abstract

We present a global 1-D conductivity model which is obtained by analysis of five years (2001–2005) of simultaneous magnetic data from the three satellites Ørsted, CHAMP and SAC-C. After removal of core and crustal fields as predicted by a recent field model we used non-polar scalar and vector observations from the night-side sector, and interpret the field residuals in terms of a large-scale contribution from the magnetospheric ring current and its induced counterpart. We then derive transfer functions between internal (induced) and external expansion coefficients of the magnetic potential and provide globally-averaged C-responses in the period range between 14 hours and 4 months. Since the satellite responses are probably influenced by induction in the oceans for periods shorter than a few days, we correct the data for this effect. Interpreting the corrected responses yields a 1-D conductivity model which is rather similar to models derived from ground-based data.

Received 2 June 2006; accepted 1 August 2006; published 16 September 2006.

Index Terms: 1515 Geomagnetism and Paleomagnetism: Geomagnetic induction; 1555 Geomagnetism and Paleomagnetism: Time variations: diurnal to decadal; 2778 Magnetospheric Physics: Ring current.

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Citation: Kuvshinov, A., and N. Olsen (2006), A global model of mantle conductivity derived from 5 years of CHAMP, Ørsted, and SAC-C magnetic data, Geophys. Res. Lett., 33, L18301, doi:10.1029/2006GL027083.