Interplanetary shock normals

Abstract

A scheme has been developed to improve the estimate of an interplanetary shock normal by using both magnetic field and plasma data from a single spacecraft. Calculation of the basic shock model employs a subset of the eight magnetohydrodynamic conservation relations for a shock in an isotropic medium. This subset consists of six equations that are devoid of pressure and temperature terms. A sigma-weighted least squares loss function technique is used to best fit the overdetermination equations with respect to the eleven parameters of the system. This procedure usually yields a normal much more accurate than the one obtained using magnetic field values alone. An example is given of the use of the technique on the data for the Pioneer 7 shock of 29 August 1966.