Geomagnetic observations on Tristan da Cunha, South Atlantic Ocean

Abstract

Few geomagnetic ground observations exist of the Earth’s strongest core field anomaly, the South Atlantic Anomaly<br />(SAA). The geomagnetic repeat station on the island Tristan da Cunha, located half-way between South Africa<br />and South America at 37° 05’ S, 12° 18’ W, is therefore of crucial importance. We have conducted several sets of<br />repeat station measurements during magnetically quiet conditions (Kp 2o or less) in 2004. The procedures are described<br />and the results are compared to those from earlier campaigns and to the predictions of various global field<br />models. Features of the local crustal bias field and the solar quiet daily variation are discussed. We also evaluate<br />the benefit of continuous magnetic field recordings from Tristan da Cunha, and argue that such a data set is a very<br />valuable addition to geomagnetic satellite data. Recently, funds were set up to establish and operate a magnetometer<br />station on Tristan da Cunha during the Swarm magnetic satellite mission (2011-2014).

Keywords

• South Atlantic Anomaly – geomagnetic observatory – geomagnetic repeat station – Tristan da Cunha