Use of champ magnetic data to improve the antarctic geomagnetic reference model

Champ total field measurements have been used to develop the new version of the Antarctic geomagnetic Reference Model (ARM). The model was conceived as a tool to evaluate the main field in Antarctica, facilitating the merging of different magnetic surveys carried on in the region from 1960 onwards. Spherical cap harmonic analysis was used to produce the model. Together with data coming from POGO, Magsat, and Orsted satellite missions, a suitable selection of Champ data based on different criteria was performed to minimise the effect of external fields. The comparison of ARM and other global models with regard to real data demonstrates the validity of our regional model, specially for the representation of the secular variation of the geomagnetic field. Since Champ satellite tracks cover the Geographical South Pole better than other satellite missions, this fact contributed to improve the model in the central region of the cap.