Energetic electron enhancements under radiation belt (Lt<t1.2) during nonstorm interval on August 1, 2008

Abstract. An unusual event of deep injections of > 30 keV electrons from the radiation belt to low L shells (L 1.2) in midnight-dawn sector occurred during nonstorm conditions on August 1, 2008. Using THEMIS observations in front of the bow shock, we found transient foreshock conditions and rotational discontinuities passing the subsolar region at that time. These conditions resulted in generation of fast magnetosheath plasma jets and penetration of the magnetosheath plasma into the magnetosphere as were observed by the THEMIS probes after approaching the magnetopause. The magnetosphere responded to variations in the IMF orientation by magnetic field perturbations. Magnetic records at ground-magnetometers of INTERMAGNET provided evidence of a global geomagnetic response in the form of geomagnetic pulses from the equator to middle latitudes. The earliest response was found at low latitudes in the predawn sector. We propose a scenario of possible association between dynamical foreshock in the subsolar region, magnetosheath plasma jets and the deepest injections of the > 30 keV electrons at L 1.2 at the midnight-dawn sector.