LOWER IONOSPHERE ION PRODUCTION, DENSITY AND COMPOSITION IN AN AURORAL ABSORPTION EVENT

A payload instrumented to measure energetic particle precipitation, ionization density and composition of ions and neutral constituents in the D- and lower E-region was launched on 21 February 1976 from Esrange into an auroral absorption event. Energetic particles were measured in the spectral range 40 to 800 keV. The reported ion composition measurements were made during rocket ascent in the height range 60-104.6 km. Water cluster ions dominated below 71km above which height NO+ was the most abundant ionic species. Negative ions were found below a very sharp ledge in concentration located at 74 km. The importance of the formation of these on the loss rate and recombination life time of positive cluster ions and hence on the positive ion composition is discussed. From the measured ion composition a height profile of nitric oxide is derived showing a concentration between 7 × 108cm-3 and 3 × 108cm-3 in the height range from 80 to 100 km. © 1979.