A Spherical Cap Harmonic Model of the Satellite Magnetic Anomaly Field Over China and Adjacent Areas

Abstract

Using Magsat data over China and adjacent areas (between latitudes 10°N and 60°N and longitudes 70°E and 140°E), a spherical cap harmonic model describing the three-dimensional structure of the satellite magnetic anomaly field has been derived. The pole of the cap was at (35°N, 105°E), its half-angle was 35°and a maximum index of 12 was used. The maximum spherical harmonic degree corresponding to this index is 31.6, giving a minimum wavelength, at the Earth's surface, of 1266km. From this model and the International Geomagnetic Reference Field (IGRF), a model of the total intensity anomaly field (ΔF) was derived. The satellite magnetic anomalies (ΔX, ΔY, ΔZ, ΔF) at an altitude of 400km were calculated and the corresponding magnetic anomaly charts have been drawn.