The airglow continuum at high latitudes—An estimate of the NO concentration

A high‐latitude (68°N) rocket measurement of the NO2 continuum at 540 nm yielded an overhead intensity of 1.14 R/Å. The volume emission profile has been used with O densities, derived from measurements of the oxygen emissions made from the same rocket, to determine the NO profile for an air afterglow, which is excited via both two‐body and three‐body recombination paths. It is concluded that the NO concentration was 8 × 108 cm−3, with a factor 2 uncertainty at the peak, and that this enhancement from quiet ionospheric conditions is probably due to extended particle precipitation prior to the launching.