Satellite studies of N(²D) emission and ion chemistry in aurorae

The incident particle flux ion and neutral composition data taken on the AE‐D satellite have been used to investigate the quantal emission of N 2 + at 4278 Å, N(²D) at 5200 Å, and the ion chemistry in aurorae. The results of a time dependent auroral model have been compared to the data. The calculated 4278 Å emission of N 2 + , the 5200 Å emission of N(²D), the densities of O 2 + , NO + , N 2 + , O + , and the electron density are generally in agreement with the measured values. These results are consistent with the branching ratios and quenching rates deduced from previous studies of the N(²D) densities in the daytime, mid‐latitude ionosphere. It is found that in an auroral arc, the measured atomic oxygen density is lower than predicted by the MSIS model.