A statistical study of Ring Current Aurora

The occurrence of Ring Current Aurora (RCA) due to precipitating ring current ions by pitch angle diffusion at sub-auroral latitudes was estimated by analyzing the TIMED/GUVI auroral images. RCA occurred at all magnetic local time (MLT) with a peak occurrence around 15:00 MLT and-65 degrees magnetic latitudes. This is consistent with the EMIC wave occurrence pattern during geomagnetic active time (Meredith et al., 2014). The occurrences were similar in both hemispheres. However, the northern hemisphere occurrence was about 3 times of that in the southern hemisphere. The hemispheric difference may be due to the differences in the loss cone sizes on con-jugated magnetic flux tubes and remains to investigated.