Energetic magnetosheath ions connected to the Earth's bow shock: Possible source of cusp energetic ions

Abstract

Plasma and magnetic field data detected by NASA GGS/Polar and Wind during the May 4, 1998, storm event are analyzed to demonstrate for the first time a causal relation between the magnetosheath energetic ions and bow shock magnetic geometry. Intense magnetosheath energetic ions observed upstream from the cusp are from the quasi‐parallel bow shock and show properties indicating that they are a possible source of cusp energetic ions.