AN IMPROVED TECHNIQUE FOR REDUCTION TO THE POLE AT LOW LATITUDES

Reduction to the pole at low latitudes based on a Wiener filtering app roach has been improved by introducing a deterministic noise model. It is assumed that the noise power is a fixed fraction of the signal pow er. 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 obse rved field. This is done by iteratively minimizing the difference betw een the measured field and the reduced-to-the-pole field projected to the geomagnetic latitude of the measured data. This results in a reduc ed-to-the-pole magnetic map that, when projected to the geomagnetic la titude of the given data, closely matches the measured data. The final reduced-to-the-pole field does not show any of the artifacts typical of reduction-to-the-pole at low geomagnetic latitudes. The method is d emonstrated on a data set from an aeromagnetic survey flown over north -central Burkina Faso, West Africa.