Electric Fields in Earth Orbital Space

A model of the ground state magnetosphere had been developed which suggested that the basic magnetosphere is formed and maintained simply by the interaction of the solar wind with the geomagnetic field. It is known, however, that the magnetosphere responds dynamically to changes in the interplanetary magnetic field (IMF). Instead of the qualitative reconnection theory, this response is examined in terms of electromagnetic wave propagation in the interplanetary region. The interplanetary plasma (solar wind) is magnetized their by the solar magnetic sector structure. Electromagnetic waves of higher frequency can propagate through the solar wind without appreciable attenuation. It is the interaction of these disturbance waves with the magnetosphere that causes the observed magnetospheric response to the IMF. The propagation of electromagnetic disturbances in the interplantary region and their interaction with the magnetosphere is examined quantitatively. Only certain modes propagate and there are further restrictions on the waves at the waves at the magnetopause. A southward IMF produces the most dramatic magnetospheric response in the tail region and a northward IMF in the polar cusp region.