Earth's Bow Shock and Its Interaction with Interplanetary Shocks

Abstract

AbstractGiven the interplanetary conditions near the Earth's orbit and the geometrical configuration of the Earth's bow shock, this paper discusses the distributions of various parameters of shock strength over the sunward shock front, and the interaction between the bow shock and interplanetary shocks. For the case of axisymmetrical bow shock front with respect to the Sun‐Earth line, we arrive at the following conclusions: (1) The parameters of shock strength are distributed symmetrically with respect to the plane of reference defined by the interplanetary magnetic field (IMF) and the Sun‐Earth line, and their maxima appear in the plane of reference. The ratio of magnetic pressure is larger on the side containing the perpendicular‐shock line, whereas the ratio of gas pressure is larger on the side containing the parallel‐shock point, leading to a distribution of the ratio of total pressure that is largely axisymmetrical with respect to the Sun‐Earth line. (2) When the angle between the IMF and the Sun‐Earth line increases, the maxima of shock strength parameters of the bow shock decrease and the maximum points shift away from the subsolar point, but the distributions of gas‐pressure ratio and total pressure ratio are essentially not affected. (3) After an interplanetary shock is transmitted through the bow shock, the ratio of tangential field strength becomes closer to 1, whereas the jump of total magnetic field strength increases in amplitude. (4) After transmission through the bow shock, the ratio of total magnetic field strength becomes closer to 1 for quasi‐perpendicular interplanetary shocks but farther away from 1 for quasi‐parallel ones.