Negative ions in the night ionosphere and the continuous sub-ELF emissions

A possible association of the nocturnal sub-ELF emissions, observed by Tepley and Amundsen, with high percentages of negative ions in the night ionosphere is discussed. Calculations show that very modest electron drifts are sufficient to excite ion-acoustic oscillations in a plasma with large percentages of negative ions. Ion-acoustic oscillations in the night ionosphere would produce oscillations in the earth's magnetic field records, very similar to those observed by Tepley and Amundsen.