Table 1.

General structure of a MIO_SHA product file. All notations are defined in the main text (Subsections 2.2 and 2.4), except θ _NGP and ϸ _NGP which stand for the colatitude and longitude of the Northern pole of the geomagnetic dipole. Each file includes two models, describing the primary ionospheric field at ground and the secondary (induced) ionospheric field, as explained in Subsection 2.4. Each model is stored as a N _d × (2N _sp ) block of coefficients, where N _d (defined in Section 2.2) is the number of dipole coefficients for a given pair of diurnal and seasonal wavenumbers and N _sp = (p_max − p_min + 1)(s_max − s_min + 1) is the number of such pairs. The first two columns contain the degree n and order m, respectively; positive (resp. negative) m values indicate that the line is that of coefficients to be multiplied by cos mϸ _d (resp. sin mϸ _d ) in the spherical harmonic expansion. In each line, coefficients are stored in columns 3 to 2N _sp + 2, by iterating on s and p, in that order.