Open Access

Spherical cap modelling of Ørsted magnetic field vectors over southern Africa

Earth, Planets and Space201453:BF03352392

Received: 6 September 2000

Accepted: 6 February 2001

Published: 18 June 2014


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.