Recombination of NO+ in the mid‐latitude trough and the polar ionization hole

The dissociative recombination of NO/sup +/ with electrons is further examined using a sample of atmosphere Explorer data from the mid-latitude ionization trough. The electron temperature for this data sample covered a range of 2500/sup 0/K, thus allowing an accurate determination of the temperature dependence of the rate coefficient. The results confirm our earlier determinations which were made from a large data base, and the rate coefficient ..cap alpha.. is found to be inversely proportional to the electron temperature. We investigate the possibility of a neglected process in the NO/sup +/ chemistry which, if it were included, might result in a smaller temperature dependence of ..cap alpha... Such a source would require a direct dependence on electron temperature. A possible candidate is associative recombination of energetic N(/sup 2/D) with O. The results confirm recent measurements which find that this process cannot be significant. The NO/sup +/ chemistry is very sensitive indicator of chemical equilibrium conditions. Using measurements of the relevant parameters made in the polar ionization hole, we find that horizontal drifts do not appear to be significant in this region.