Wave guide propagation of micropulsations out of the plane of the geomagnetic meridian

A numerical solution is obtained for the coupled differential equations governing the propagation of Pc 1 micropulsations in the ionospheric wave guide in directions out of the plane of the geomagnetic meridian. A significant difference from previously obtained in-meridian results is the appearance of resonant absorption peaks at certain frequencies. The resonances arise from coupling between the ‘ducted’ mode and the ‘field-guided’ mode, which removes energy from the wave guide. The resonant frequencies depend on ionospheric parameters and dip angle, but not on the direction of propagation. The amplitude of the resonances, however, increases with deviation from the geomagnetic meridian. The existence of geographically dependent frequency passbands implied by these results makes it questionable that micropulsations can propagate without appreciable attenuation in directions other than geomagnetic N-S or possibly geomagnetic E-W.