An improved technique for reduction to the pole at low latitudes

Abstract Reduction to the pole at low latitudes based on a Wiener filtering approach has been improved by introducing a deterministic noise model. It is assumed that the noise power is a fixed fraction of the signal power. This allows the method to be fully automated. Further improvement is obtained by requiring the reduced-to-the-pole field to map into the observed field when projected to the geomagnetic latitude of the observed field. This is …