Rocket measurements of upper atmospheric nitric oxide and their consequences to the lower ionosphere

Abstract

The nitric oxide density profile in the upper atmosphere between 70 and 110 km was measured with scanning ultraviolet spectrometers aboard two Nike-Apache rockets on February 6 and January 31, 1969. The observed nitric oxide density profile has a maximum of about 108 cm−3 at 105 km, and a minimum of about 107 cm−3 at 85 km. Photochemical equilibrium is prevalent at about 85 km while mixing dominates below that altitude. A model in which nitric oxide is formed from N(2D) atoms can explain the observed features of the height profile. The contribution of nitric oxide ionization by solar Lyman-α to the total ion production is dominant in the middle D region (below 90 km) for the solar activity level at the time of the experiments. Dissociative recombination of nitric oxide ions is the main loss process in the region above 85 km. Below that height, a faster mechanism is required.