An Investigation into the Use of Satellite Data to Develop a Geomagnetic Secular Variation Model over Southern Africa

There is a need to develop secular variation (SV) models using satellite data as the use of ground data is not always possible. Ground data has many limitations including limited data points and lack of data over ocean areas that are not easily accessible. Two regional geomagnetic field modelling techniques, namely polynomial surface modelling (PolyM) and Spherical Cap Harmonic Analysis (SCHA), were applied to CHAMP satellite data recorded between 2001 and 2005 to investigate the use of satellite data to develop a geomagnetic SV model over southern Africa. The resulting regional models of this investigation were validated against the two widely used global field models IGRF 10 and CHAOS-2 using the available ground survey data obtained during the same period over southern Africa. The results suggest that the regional field models can be derived based entirely on satellite data. However, the regional SV models can be improved using both high quality satellite and ground survey data, since they lack the high quality of a global field model like CHAOS-2.