Global comparison of magnetospheric ion fluxes and auroral precipitation during a substorm

摘要: [1] Integrated fluxes from global images taken by the High Energy Neutral Atom (HENA) and far ultraviolet (FUV) imagers on IMAGE spacecraft were compared for a six-hour period, during which reasonably intense substorm occurred. HENA FUV proton auroral imager (SI-12) monitor emissions are representative of trapped precipitating magnetospheric fluxes, respectively. For several hours prior to onset, measurements lower energy (10-16 16-27 keV) Energetic Atoms (ENA-s) protons SI-12 show strong similarities, with implication that, in general, precipitation is controlled steady pitch angle diffusion process. Less similarity seen between ENA-s electron precipitation, monitored Wideband Imaging Camera. Prior ENA intensity at large radial distance (L > 8) reduced while overall integrated flux increases signifying earthward motion accumulation plasma. About 20 minutes before decrease continues grow. The observations consistent pre-onset increase plasma pressure inner magnetosphere without an showing more efficient trapping perhaps distorted nightside magnetosphere. At onset very sudden gradual intensification energetic continues. aurora shows one order magnitude, only 50%. relatively short lived (∼10 minutes) enhancements last about hour.