Ionospheric Features of Polar Cusp Dayside Precipitation for a Northern IMF

Geophysical processes in the region of the dayside polar cusp on December 22, 2003, were studied for a northern orientation of the interplanetary magnetic field (IMF) and a relatively high-velocity, low-density solar wind, using ground-based optical observations in Svalbard and DMSP F16 satellite data. Comparison of satellite and ground-based observations shows that soft electron precipitation in the cusp region determines the auroral glow in the 630.0 nm (OI) emission. The peculiarity of the considered event is observation of a bright rayed arc of the aurora rimming the dayside cusp from its polar edge. The results of observations by the low-flying DMSP F16 satellite as it intersected the rayed arc were analyzed. Explanations for the observed phenomena are proposed, based on analysis of changes in the spectra of precipitating electrons and formation of a field-aligned electron beam by the field-aligned electric field.