The Aurora, the Radiation Belt and the Solar Wind : A Unifying Hypothesis

Abstract

RECENT high time resolution spectroscopic studies of the aurora¹ at College, Alaska, have revealed a rather consistent pattern in the spatial distribution of the hydrogen emission lines. It was observed that during the first phase of a typical polar auroral display the intensity peak of the hydrogen emission would shift in a continuous fashion from the northern horizon to the southern horizon in 1-3 hr. During nights of moderate auroral activity the intensity peak would remain near the southern horizon and then recede back to the north at the conclusion of the display, some time after midnight. Nights of strong auroral activity were characterized by the hydrogen emission features either disappearing below the local southern horizon, or being present in the entire portion of the magnetic meridian monitored by the spectrograph. The shift in zenith distance is interpreted as reflecting a change in the geomagnetic co-latitude of the incoming protons, as described below. The solid line in Fig. 1 represents typical data obtained in a six-day period.