Improved observations at the southern African geomagnetic repeat station network

Within the Inkaba yeAfrica project, the number of geomagnetic repeat stations surveyed in southern Africa has been increased recently from eight to almost 40, through cooperation between Hermanus Magnetic Observatory (HMO), South Africa and GeoForschungsZentrum Potsdam (GFZ), Germany. Taking advantage of the extensive network of well-marked repeat stations formerly established by HMO in South Africa, Namibia and Botswana, and experience gained in using on-site variometers in former repeat station surveys carried out by GFZ, we could significantly improve the spatial data coverage of the area and also the quality of the results. Here we report on the survey and data processing methods, and discuss the accuracy of results, particularly with respect to the ability of the data to reflect the undisturbed internal magnetic field. Moreover, we briefly discuss how differences in the variometer recordings can reflect possible lateral changes in lithospheric conductivity.