Nightside detached auroras due to precipitating protons/ions during intense magnetic storms

[1] Nightside detached auroras ( NDA) during intense magnetic storms are studied by using FUV image data from Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics ( TIMED)/ Global Ultraviolet Imager (GUVI), Imager for Magnetopause-to-Aurora Global Exploration ( IMAGE)/ FUV, and particle data from DMSP/SSJ/4 instruments. We found that NDA are caused by proton/ ion precipitation only. Thin arc-shaped NDA are very likely due to soft (<1 keV) proton/ ion precipitation. Thick or patch-shaped NDA are caused by energetic (similar to10 keV) proton/ ion precipitation. All the cases indicate that the NDA were observed when Dst was less - 130 nT. More specifically, the NDA occurred during recovery or the lowest Dst period for each intense storm. The magnetic latitudes of the NDA are between 45degrees and 55degrees ( L shell: 2.0-3.0). We found that the latitude location of the NDA is quasi-linearly correlated with Dst. The magnetic local time ( MLT) of the NDA ranges from 1930 to 0300. All the facts indicate that the source of the NDA is the trapped protons/ ions in the ring current. Precipitation of the trapped protons/ ions is caused by an interaction between the perpendicularly heated ring current particles and the cold/dense plasma at the plasmapause.