SIGNATURES OF SHOCK DRIVERS IN THE SOLAR-WIND AND THEIR DEPENDENCE ON THE SOLAR SOURCE LOCATION

Solar wind and energetic ion observations following 40 interplanetary shocks with well-established solar source locations have been examined in order to determine whether signatures characteristic of the coronal material forming the shock driver are present. The signatures considered include magnetic-field-aligned bidirectional ion flows observed by the ISEE 3 and IMP 8 spacecraft: bidirectional solar wind electron heat fluxes: solar wind plasma proton and electron temperature depressions; low-beta plasma; enhanced, low-variance magnetic fields: and energetic ion depressions. Several shock driver signatures are commonly observed following shocks originating from within approximately 50-degrees of central meridian and are generally absent for other events. We conclude that shock drivers generally extend up to approximately 100-degrees in longitude. centered on the solar source longitude. A particular shock driver signature is typically found following approximately 80% of shocks from near-central meridian events. However, only approximately 20% of shocks from near-central meridian events are associated with the bidirectional 35-1000 keV ion events discussed by Marsden et al. (1987). Since shocks from central meridian events are not usually associated with all the shock driver signatures examined, the absence of a driver cannot be confirmed from consideration of one of these signatures alone. We also find evidence that a few bidirectional energetic ion and solar wind electron heat flux events following shocks (in particular from far eastern sources) may occur on open field lines outside of shock drivers.