Review of auroral morphology, auroral dynamics, and modern observational techniques

Our present understanding of auroral morphology has been developed in a large part from a vast accumulation of all-sky camera photographs taken at many stations around the world. In order to further our understanding of the concepts of the auroral oval and the auroral substorm and their relation to influences on our atmosphere, we now need to express these concepts in terms of the latitudinal distribution of the type and energy of the associated incident particles. In this review, data are presented on precipitating particles in the evening and midnight sectors in relationship to the electron trapping boundary motion within the substorm. The complex height distribution of ionization associated with particle precipitation shows some of the possible complexities in the interpretation of incoherent scatter radar data obtained in the auroral regions. Data obtained by modem satellite imagery can provide the auxiliary data needed to understand the particle effects in the polar regions. The rapid temporal and spatial changes in the aurora are seen in data from rapid scanning photometer systems and high sensitivity color television systems. The general review of these data attempts to show that local auroral dynamics and the phase and global extent of the auroral substorm imply drastic changes in the incident particle energies. These in turn produce variable atmospheric effects of direct concern to all incoherent scatter radar studies of the neutral and ion composition, temperature, and motion of the earth's atmosphere.