Multi-Spacecraft Observations of Interplanetary Shocks in the ISTP Era

Interplanetary shocks near Earth have been observed, even with multiple spacecraft, since the very beginning of the space age. The ISTP fleet of upstream solar wind monitors (WIND, IMP 8, ACE and on occasion Geotail and Interball and mosr recently Cluster) allowed the collection of a very large database of a wide range of interplanetary shocks observed by two or more spacecraft in a variety of configurations. This talk will review the observed characteristics of the shocks based on in-situ observations. Also the various shock fitting techniques available today will be compared and sources of uncertainties in the obtained shock surface normals and speeds will be discussed. Cases with demonstratible surface curvatures will be shown along with highly complex observations defying simple interpretations. Special emphasis will be placed on the largest and strongest shocks that may have the most pronounced geomagnetic effects.