CHAMP, Ørsted, and Magsat Magnetic Anomalies of the Antarctic Lithosphere

Abstract

We processed CHAMP, Orsted and Magsat mission data for the Antarctic using advanced spectral correlation theory to separate spatially and temporally static components from the dynamic ones. Ignoring measurement noise and processing errors, the dynamic components include strong external field effects, whereas the static components reflect lithospheric and core field effects. Consistency is apparent in the correlation of all the anomaly fields at degree and order 13 and higher. However, the longer wavelength components are corrupted by errors in the core field reductions that do not account for the crustal thickness magnetic effects. To assess these magnetic effects, we developed an Antarctic crustal thickness model from free-air and computed terrain gravity effects. The pseudo magnetic effects evaluated from the crustal model indicate quite strong crustal anomaly contributions for degrees lower than 13 in the satellite magnetometer observations. The Antarctic gravity field from which the crustal thickness effects were inferred is limited by the general lack of terrestrial gravity observations. However, CHAMP is providing significant new insight on the magnetic and terrestrial gravity fields for advancing our understanding of the Antarctic lithosphere and its tectonic evolution