A Study to Relate Interplanetary Magnetic Field Parameters to Auroral Oval Phenomena.

The first part of this report summarizes the major results of a study of auroral oval phenomena and interplanetary magnetic field. The second part presents an up-dated understanding on the auroral oval phenomena and their relation with the interplanetary magnetic field. It reviews research involved with direct and inferred determinations of the polar cap size and location, as well as their relationships with the interplanetary magnetic field. First, the progress in the observation and understanding of polar cap size variations as related to changes of the interplanetary magnetic field magnitude and direction is reported. Obtained by scaling the global auroral distributions from DMSP auroral pictures, some new results on configurational changes of the auroral oval (i.e., the polar cap) with different orientations of the interplanetary magnetic field are also discussed. There are indications of the dawn-dusk and sunward-tailward displacements of the auroral oval in association with the interplanetary magnetic field B sub y and B sub x components, respectively. It is obvious from this review that a better understanding of the interaction between the terrestrial magnetosphere and the interplanetary magnetic field requires further efforts, both observational and theoretical.