A Comparative Evaluation for the Southern African Region of DGRF90 and IGRF95 Candidate Models

Abstract

The 1995 revision of the International Geomagnetic Reference Field (IGRF) comprises a definitive main-field model for 1990.0, a main-field model for 1995.0, as well as a prediction secular-variation model for the period 1995-2000. The proposed main-field models have been evaluated by comparing them with results of magnetic surveys conducted by the Hermanus Magnetic Observatory over the Southern African sub-continent, including countries like South Africa, Namibia, Botswana, and Zimbabwe. The secular-variation models on the other hand have been compared with secular variation estimates based on rates of change as observed at the various field stations during 1990-1995.