Ring current and polar rain auroras

Hot ring current ions are usually trapped in the inner magnetosphere. However, during geomagnetic or solar wind disturbances, the hot ions can precipitate into the ionosphere and cause ring current auroras (RCA) via pitch angle diffusion. The spatial structures of RCA strongly depend on magnetic local time. On the other hand, hot keV electrons in the solar wind can also precipitate into the polar cap on open field lines and create polar rain auroras (PRA). PRA show a number of spatial features, relatively uniform, dawn-dusk aligned bars, and gaps near the nightside oval. These features are likely caused by the high latitude magnetopause disturbances and the magnetotail reconnection. All of these features and their possible application in remote sensing of the magnetosphere will be discussed using data from satellites, such as IMAGE, TIMED and DMSP.