Combined mass spectrometric composition measurements of positive and negative ions in the lower ionosphere—II. Negative ions

Negative ion composition measurements of the lower ionosphere made simultaneously with positive ion measurements show some interesting features not previously observed. The higher sensitivity of this instrument allowed for detection of numerous previously undetected species. A layer of heavy ions (> 100 a.m.u.) was observed to exist between 80 and 90 km. The properties of this layer seem to indicate a meteoric source. The heavy ions are seen to exist down to the lowermost heights measured and their abundance increases below 58 km indicating a stratospheric source. Besides these ions, numerous new light ions were also seen. Their abundance level and sources are discussed.