The incident particle flux ion and neutral composition data taken on the AE-D satellite have been used to investigate the quantal emission of N2+ at 4278 ¿, N(2D) at 5200 ¿, and the ion chemistry in aurorae. The results of a time dependent auroral model have been compared to the data. The calculated 4278 ¿ emission of N2+, the 5200 ¿ emission of N(2D), the densities of O2+, NO2+, O+, and the electron density are generally in agreement the measured values. These results are consitent with the branching ratios and quenching rates deduced from previous studies of the N(2D) densities in the daytime, mid-latitude ionsphere. It is found that in an auroral arc, the measured atomic oxygen density is lower than predicted by the MSIS model.