Geomagnetic quiet time (sq) variations at high latitudes

Abstract

The availability of geomagnetic data from two Antarctic Geophysical Observatories (AGOs P5 and P6; invariant geomagnetic latitudes 87° and 85°S) in the deep southern hemisphere polar cap allows for the first time the study of the geomagnetic "quiet time" variations (Sq) at the highest latitudes possible. We present analyses of the Sq variations at these two AGO sites for data obtained in 1997, and compare them with model predictions. We find strong evidence that the Sq variations near 90°S geomagnetic latitude are considerably larger (factor of two or more) than would be expected from the model, independent of season. Comparison of the measurements of the vertical components to the model suggests that there may be large differences in the Earth's deep mantle conductivity under the Antarctic ice cap at the two locations. These observations highlight the need for incorporating high latitude data into Sq models.