Em. Warrington et al., LARGE HF BEARING ERRORS FOR PROPAGATION PATHS CONTAINED WITHIN THE POLAR-CAP, IEE proceedings. Microwaves, antennas and propagation, 144(4), 1997, pp. 241-249
Large electron-density gradients in the polar-cap ionosphere, associat
ed with the convection of patches of overdense plasma and the presence
of high-latitude auroral arcs, produce tilted reflecting surfaces whi
ch result in HF signals propagating over paths well displaced from the
great circle. Measurements have been made at a very high-latitude rec
eiving site of signals propagated over paths contained within the pola
r cap. Systematic swings in the bearing of the received signal of up t
o +/-100 degrees from the great circle path were recorded and their ch
aracteristics related to the directional components of the interplanet
ary magnetic field and the level of geomagnetic activity, as these geo
magnetic parameters play an important role in determining the state of
the high-latitude ionosphere.