Case Study of Asymmetries in Polar Rain Aurora

Polar rain aurora (PRA) phenomena are caused by the precipitation of polar rain electrons, which originate from the solar wind. While PRA often has a symmetrical and homogeneous shape, we have identified multiple events that exhibit unique spatial variations and asymmetries. This case study focuses on a single PRA event on October 27, 2003 that presents an especially interesting inquiry. In this event, the PRA is band-shaped, strongly tilted towards the dawn side, and shifted from the center of the auroral oval. Additional detailed analysis was performed on this case, including time history of solar wind conditions, supporting observations from the DMSP F13 satellite, and consideration of convection patterns. Furthermore, we have identified and mapped a structure in the solar wind that later appears in the ionosphere, suggesting that the spatial variation exhibited in the October 27, 2003 event is likely caused by spatial structures in the solar wind superthermal electrons.