The Local Time Propagation of Electron and Proton Shock-Induced Aurora and the Role of the Interplanetary Magnetic Field and Solar Wind

Shock-induced aurora observed with satellite-borne ultraviolet imagers shows distinct characteristics from the more common and extensively studied aurora generated during magnetospheric substorms. It is initiated in the noon sector immediately following dynamic pressure pulses associated with the arrival of enhanced solar wind plasma at the front of the magnetosphere. The brightness enhancement rapidly propagates toward the dawn and dusk sectors and may trigger the development of an auroral substorm on the nightside. The FUV imaging system on board the IMAGE satellite has the ability to discriminate between proton and electron precipitation. This feature has been used to study the morphology and dynamics of the electron and proton precipitation following pulse-induced magnetospheric perturbations. A set of 14 cases occurring during positive and negative Bz periods has been selected and studied. A different dynamics is observed for aurora caused by electron and proton precipitation. The important role played by the Bz component of the interplanetary magnetic field is analyzed as well. A correlation between the precipitated power deduced from FUV images and solar wind (SW) and interplanetary magnetic field (IMF) measured by ACE is presented. The effect of SW and IMF conditions prevailing before and during the shock on shock aurora is studied separately in order to distinguish the role of the preconditioning of the magnetosphere and the effects induced by the shock itself. The time evolution of the injected power is also studied in the entire oval and in individual MLT sectors.