TERRAPUB Earth, Planets and Space

Earth Planets Space, Vol. 58 (No. 4), pp. 409-416, 2006

Deriving main field and secular variation models from synthetic Swarm satellite and observatory data

Vincent Lesur, Susan Macmillan, and Alan Thomson

British Geological Survey, Murchison House, West Mains Road, Edinburgh, EH9 3LA, UK

(Received November 18, 2004; Revised April 19, 2005; Accepted September 30, 2005; Online published April 14, 2006)

Abstract: We investigate how well the core field component of the underlying model used in the Swarm End-to-End simulator can be recovered when relatively simple geomagnetic field models are fitted to synthetic Swarm satellite and observatory data. In particular we demonstrate the potential benefits of Swarm by deriving models without these data. From two years of observatory data, the underlying secular variation model is recovered up to about spherical harmonic degree 8. This maximum degree is higher than was expected but increases to 10 when satellite data are also used. The constant part of the geomagnetic field model is recovered to at least degree 17. These results improve when a better statistical treatment of the data errors is made, a slightly more complex field model is fitted, or when five years of data are used.
Key words: Geomagnetism, geomagnetic field, swarm.

Corresponding author E-mail: V.Lesur@bgs.ac.uk

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