Earth Planets Space, Vol. 57 (No. 12), pp. 1165-1171, 2005

The IZMIRAN main magnetic field candidate model for IGRF-10, produced by a spherical harmonic-natural orthogonal component method

Vadim P. Golovkov, Tatiana I. Zvereva, and Tatiana A. Chernova

Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation, IZMIRAN, Troitsk, Moscow Reg., 142190, Russia

(Received December 6, 2004; Revised June 22, 2005; Accepted June 28, 2005)

Abstract: A simple method is proposed for constructing a space-time model of the main magnetic field based on the high-accuracy satellite survey data. At the first stage, we expand the CHAMP daily mean data into spherical harmonics with constant coefficients. It provides us with a series of the daily mean spherical-harmonic models (DMM) over a survey interval of several years, which are, then, expanded into the natural orthogonal components (NOC). It is shown that the NOC series converges rapidly, and that the accuracy of the space-time model over the time interval under consideration is no worse than the accuracy of the traditional models.
Key words: Secular variation, satellite data, natural orthogonal components, spherical harmonic models.