Ionization from soft electron precipitation in the auroral F region

Rocket‐borne instrumentation, launched into the morning sector auroral zone from Sondre Stromfjord, Greenland, detects electron density enhancements correlated with enhancements in the flux of soft (less than 1 keV) downgoing electrons. These electron density enhancements seem most likely to have been generated by direct production of ionization at F region altitudes. Model calculations of the electron impact ionization rate, based on the measured electron spectrum, lend support to this hypothesis.