Temporal versus spatial geomagnetic variations along the west coast of Greenland

Information about the intensity and spatio-temporal characteristics of geomagnetic activity is of interest to aeromagnetic surveyors because a successful magnetostatic anomaly survey relies on the ability to distinguish between spatial and temporal magnetic variations. The latter are usually recorded at a fixed reference magnetometer station. We examined about six months of data collected with the Greenland west coast magnetometer chain at 1-s sampling rate and investigate to which extent temporal geomagnetic variations in selected frequency bands (1, 10 and 100 mHz) are correlated between neighboring sites (which are spaced by 190 km on the average). It appears that the differences between geomagnetic total field variations recorded at neighboring stations are significantly smaller than the magnitudes of the variations themselves. We further set a threshold of 20 nT for very quiet conditions and find that in general broadband total field variations exceed this threshold almost twice as often as the differences between geomagnetic variations at neighboring sites.