The cluster magnetic field data from several year’s worth of aurora oval crossing is used 
to quantify the temporal variations of magnetic field signatures of field-aligned currents 
(FAC). The method used is  to study the cross-correlation between pairs of spacecraft as a 
function of the temporal separation of the auroral crossings of the respective spacecraft. 
When the method is applied on the large-scale variations associated with the whole 
auroral pass, it gives results consistent with those of an earlier smaller study using low-
altitude measurements of particle fluxes. We then apply the method to study the temporal 
stability of FAC as a function of latitude, local time, geomagnetic parameters, and the 
scale sizes of the magnetic field variations. The use of a variation of this method to 
discriminate between temporal and spatial variations is discussed.