Earth Planets Space, Vol. 52 (No. 12), pp. 1199-1206, 2000
A. W. P. Thomson
Global Seismology and Geomagnetism Group, British Geological Survey, West Mains Road, Edinburgh, EH9 3LA, Scotland, U.K.
(Received February 14, 2000; Revised July 3, 2000; Accepted July 12, 2000)
Abstract: Olsen's method (Olsen, 1996) is applied to Magsat magnetic field data to deduce average quiet-time and active-time 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.