Ionospheric features of dayside polar cusp precipitation under the northward IMF

The geophysical processes in the dayside polar cusp on December 22, 2003 under the northern orientation of the interplanetary magnetic field (IMF), relatively high speed and low density of the solar wind by using the ground-based optical observations on Spitsbergen and DMSP F16 spacecraft observations were examined. A comparison of spacecraft and ground-based observations shows that soft electron precipitation in the cusp region determine the region of the auroral luminosity in the (OI) 630.0 nm emission. The peculiarity of the event under consideration is the observation of a bright rayed auroral arc bordering the dayside cusp from its polar edge. The results of observations of the low-altitude DMSP F16 spacecraft during its pass over the rayed arc were analyzed. Explanations of the observed phenomena are proposed based on the analysis of changes in the spectra of precipitating electrons and the formation of an electron beam by a field-aligned electric field.