Spherical cap modelling of Ørsted magnetic field vectors over southern Africa

Abstract

Vector magnetic field observations by the Ørsted satellite during geomagnetic quiet conditions around January 1, 2000, have been employed to derive a spherical cap harmonic model (Haines, 1985) over the southern African region between 10° and 45° South in latitude and between 10° and 45° East in longitude. In the process a total of 9283 vector (27949 component) Ørsted observations have been used to derive a spherical cap model with minimum wavelength resolution approximately 1200 km. This model is compared with the global Ørsted magnetic field model (Olsen et al, 2000a) in terms of a fit to observatory and repeat station data over the southern African subcontinent where the Hermanus Magnetic Observatory conducts field surveys at regular 5 year intervals. © 2001, The Seismological Society of Japan, Society of Geomagnetism and Earth, Planetary and Space Sciences, The Volcanological Society of Japan, The Geodetic Society of Japan, The Japanese Society for Planetary Sciences. All rights reserved.