Geomagnetic measurements made on the moving ICE shelf at Halley,Antarctica

The difficulties involved in making geomagnetic measurements from the moving ice shelf at Halley are considered, as are measurements giving information on this movement. These indicate that the observatory has been moving westward, accelerating from 400 m yr^–1 in 1969 to 800 m yr^–1 in 1980, and rotating at up to 30 min of arc yr^–1. The effects of both rotation and tilt on the two types of variometers installed are examined. It is concluded that the geomagnetic data obtained from Halley since 1969 are best treated as variation data.