Fig. 1From: A harmonic spline magnetic main field model for Southern Africa combining ground and satellite data to describe the evolution of the South Atlantic Anomaly in this region between 2005 and 2010The long-term decrease in total field intensity over southern Africa. Evolution of total field intensity from 1940 to 2010 at Hermanus (HER), Hartebeesthook (HBK) and Tsumeb (TSU) magnetic observatories in southern Africa. There is a decrease of 20% of total field intensity at Hermanus between 1940 and 2010Back to article page