A model of the secular change of the geomagnetic field for Antarctica

An improved model of geomagnetic secular change for the Antarctic was developed using observatory annual mean values measured in Antarctica during the last 40 years. Spherical cap harmonic analysis (SCHA) with a power series time dependence was used to model spatial and temporal variations of main field differences at spatial wavelengths from 3000 to 13,000 km. The model was designed to facilitate merging satellite, airborne, marine and terrestrial magnetic data sets recorded at very different epochs in the Antarctic where significant annual geomagnetic changes have occurred. It improves the fit to observatory data by up to about 50% relative to the International Geomagnetic Reference Field