Polynomial modelling of CHAMP satellite data to investigate rapid secular variation fluctuations over southern Africa during 2003 and 2004

Polynomial surface modelling is one of several useful methods to represent the geomagnetic field over a restricted area. This technique was applied to CHAMP satellite data for the period 2001–2005 to investigate rapid secular variation fluctuations at 400 km altitude over southern Africa region between 10° and 40° South in latitude and between 10° and 40° East in longitude. The results are compared with an analysis of monthly time series data of 2 magnetic observatories in the region, namely, Hermanus (HER) in South Africa and Tsumeb (TSU) in Namibia. Consequently 2 rapid secular variation fluctuations are identified around 2003.0 and 2004.0 respectively.