Propagation of interplanetary shocks through the solar wind and magnetosheath

In order to estimate the propagation of interplanetary (IP) shocks in the solar wind and magnetosheath, we have analyzed a number of events for which simultaneous observations in the solar wind and magnetosheath were available. Among these events, those for which the arrival of the shock is observed by at least four spacecraft located in the solar wind are of a special interest. Assumption of a planar shock geometry for these cases allows to calculate directly global parameters of a shock from the times of the shock identifications by a particular spacecraft. We are presenting two distinct examples to demonstrate an evolution of IP shocks in the solar wind and magnetosheath. Using shock parameters in the solar wind and observations of the shock in the magnetosheath, we estimated the propagation speed of the corresponding magnetosheath disturbance. The observed shocks seem to decelerate while penetrating from the solar wind into the magnetosheath. Nevertheless, the speed of corresponding magnetosheath disturbance is much higher than that previously reported. (C) 2006 COSPAR. Published by Elsevier Ltd. All rights reserved.