Geomagnetic field modeling from satellite attitude control magnetometer measurements

Abstract

To demonstrate the utility of satellite attitude control magnetometer measurements for mapping main field variations, we analyzed the three‐axis magnetometer (TAM) measurements that provide attitude control for the KOMPSAT‐1 satellite. Initial processing involved transforming the TAM's magnetic measurements from the Earth‐Centered Inertial coordinates (ECI) to the Earth‐Centered Earth‐Fixed coordinates (ECEF) and then to spherical coordinates. The magnetic field of the satellite body produces symmetric signatures in the ascending and descending orbital measurements and thus can be readily removed. Spectral correlation filtering of the orbital observations helped to eliminate the dynamic external field and solar activity noise components. The ascending and descending data were then spectrally reconstructed to estimate the total magnetic field with minimum track line noise. Correlation coefficients of 0.97 and 0.96 mark the correlation of the KOMPSAT‐1 total geomagnetic intensity map with the Ørsted and IGRF2000 core magnetic field models, respectively. Power spectra from Gauss coefficients of KOMPSAT‐1 model showed closeness with the models from Ørsted data and IGRF2000 model. The spherical harmonic coefficients calculated from the KOMPSAT‐1 model by conjugate gradient inversion are strongly coherent with the Ørsted and IGRF2000 coefficients through degree 9.