Quiet-time magnetic variations at high latitude observatories

The quiet-time geomagnetic variations at high latitudes have not been systematically studied so far. Here we present quiet-time variation results from more than two years of continuous magnetic observations in Fennoscandia and Svalbard using the IMAGE magnetometer network. The CHAMP CO2 model is found to yield an excellent secular variation correction with a simple linear trend. The effect of the magnetospheric ring current on the quiet-time field values for each component is presented with the coefficients for the expected linear correlation with the D_ST index. A general trend for these coefficients is found for the CGM latitudes from 54 to 68 degrees. In this area the diurnal variation is well in accordance with the expected seasonal S_q behaviour. North of the Fennoscandian mainland the D_ST coefficients and the diurnal variations show an unexpected behaviour and additional current systems are presented as a likely cause. An objective, automated baseline method used in this study is also introduced as a method useful for various applications.