Intermediate shocks: Observations

Observations of intermediate shocks were first reported at the 1991 fall AGU meeting for one case /25/ and also at the 1992 fall AGU meeting for two more cases /26, 6/. Kivelson et al. /15/ presented one possible intermediate shock observation along the Venus bow shock during the Galileo space flyby. Chao ct al. /7/ gave the first critical study of an event and have shown the case to be an intermediate shock. A best fit procedure was used to show that the measured plasma and magnetic field on both sides of the discontinuity satisfy the Rankine-Hugoniot relations for an intermediate shock. It was also demonstrated that the Observed magnetic field structures in the shock transition region resemble that generated from a hybrid code simulation. Recently, Liu /17/ also found a possible intermediate shock from the Helios 2 data. review begins with an overview of the observations of these intermediate shocks. Then, a detail review of the identified intermediate shock by Chao et al. /7/ will be given. A useful procedure for identifying intermediate shocks will be proposed.