Interplanetary shocks (IPS) can initiate prompt acceleration of relativistic electrons in the Earth’s radiation belt, which is related to the generation and propagation of impulsive electric field (IEF). We investigate the effect of IEF on accelerating radiation belt electrons in the 6 September 2017 IPS event. A ‘surfing’ effect of electrons with respect to the electric field, referring to electrons that drift together with the tailward-propagating IEF in the duskside, is investigated in this study. Our results show that the maximum increase of electron differential flux is at 3.4 MeV by a factor of 2.2, corresponding to a drift velocity of 531 km/s, which is more consistent with the IPS propagating speed of 621 km/s rather than the fast-mode speed of 1074 km/s. We suggest that the effect of IPS propagation is important for radiation belt dynamics, and we highlight the potential importance of the parameter of IPS propagation speed.

外辐射带,行星际激波,地球磁层