Abstract
The spatial distribution of the geomagnetic field in Japan has been approximated by the secondary polynomial of latitude and the longitude. In this paper, the spherical cap harmonic analysis is employed to produce the spatial model of geomagnetic field for epoch 2000, based on the observed data from magnetic observatories, the continuous geomagnetic stations and the first-order geomagnetic stations in Japan. The pole of the spherical cap is at (37°N, 137°E) and the half-angle is 12°, the maximum index Kmax of spherical cap harmonic expansions is determined to be 3 according to the AIC analysis. Using the model, we calculated the spatial distribution of X, Y, Z and F components for epoch 2000 in Japan. The root mean square residuals of the model are 102nT in X component, 107nT in Y component, 142nT in Z component and 120nT in F component.
