Polar cap F‐layer auroras

Abstract

Polar cap auroras were measured at Thule Air Base, Greenland in December 1979, using an all sky imaging photometer. These images combined with digital ionosonde measurements, show the orientation, structure, and drift motion of sun‐aligned, F layer auroras. Drifts in both the dawn‐to‐dusk and dusk‐to‐dawn direction were observed. These auroras were not visible on the all sky camera films; however, coincident Defense Meteorological Satellite Program (DMSP) precipitating electron measurements show that these arcs are produced by fluxes of low energy (E<500 ev) electrons. Simultaneous satellite‐to‐ground signal amplitude measurements show that these auroras are accompanied by km scale size ionospheric irregularities, which cause strong amplitude fluctuations (scintillation) on the received satellite signal. Copyright 1981 by the American Geophysical Union.