Pole Reduction with Variable Geomagnetic Field Parameters

Because of the dipolar nature of the geomagnetic field, magnetic anomalies located anywhere other than at the<br>magnetic poles are asymmetric even when the magnetic source distribution is symmetrical. Pole reduction takes the<br>anomaly and transforms it into that which would have been measured if the body had lain at the magnetic pole. The<br>algorithm is usually applied in the frequency domain which has the disadvantage of restricting the application of the<br>algorithm to regions possessed of constant geomagnetic inclination and declination. A simple algorithm for pole<br>reduction is suggested here that employs a Taylor series expansion in the space domain. The algorithm is<br>demonstrated both on synthetic data and on aeromagnetic data from the Northern Territories, Australia.