Improving the modelling of the geomagnetic main-field: Isolating the average ionospheric field in satellite data

Abstract

Olsen's method (Olsen, 1996) is applied to Magsat magnetic field data to deduce average quiet-time and activetime ionospheric current systems at middle to high North and South latitudes. Spot magnetic field values at ground level are calculated from the average models and are 'ground-truthed' against observatory data. The results suggest that synoptic ionospheric models from Magsat-quality satellite data may be helpful in reducing the contamination of the main-field by non-field-aligned ionospheric sources. We discuss how the technique may be applied to data from the Ørsted mission and the extent to which these ionospheric field models may therefore be useful in improved modelling of the geomagnetic main field.

Earth magnetic field modeling from Oersted and Champ data

“…As is well known, this is not an easy task (Olsen, 1996;Thomson, 2000). It is nevertheless possible to estimate the magnitude of the ionospheric contribution to the internal Gauss coefficients.…”