Unusual auroral features observed on January 10‐11, 1983 and their possible relationships to the interplanetary magnetic field

We report unusual auroral features observed by the DMSP‐F6 satellite on January 10 and 11, 1983. These features include the shift of the most active region to the morning sector, the shift of the polar cap center toward the evening sector, a large number of sun‐earth aligned arcs and the oval‐shaped diffuse glow without bright oval arcs. The simultaneous magnetic field observations by the ISEE‐3 and IMP‐8 satellites, together with a simple magnetospheric modeling result, suggest that the unusual features result from both the unusually large B y and a large positive B z component of the IMF.