On continuous versus discontinuous neutral lines at the dayside magnetopause for southward interplanetary magnetic field

Abstract

During intervals of southward interplanetary magnetic field (IMF), it is thought that magnetic reconnection occurs along an extended region of the dayside magnetopause. The reconnected magnetic field lines are believed to transport solar wind plasma into the magnetosphere and into the high-latitude ionosphere. The precipitation pattern therefore provides information on the location and extent of reconnection at the magnetopause. This study uses observations of the energy and local time distribution of energetic proton precipitation into the dayside ionosphere during periods of southward IMF from the Far UltraViolet (FUV) imager on board the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) spacecraft. These precipitation patterns suggest that the magnetic neutral line can be discontinuous across the dayside magnetopause.