ULYSSES OUT-OF-ECLIPTIC OBSERVATIONS OF INTERPLANETARY SHOCKS

Interplanetary shocks observed at the Ulysses spacecraft as it travele d from the ecliptic plane to the southern solar pole have been identif ied and analysed using both magnetic field and plasma measurements. Th e latitude dependences of various parameters associated with the shock s (beta, theta(BN) and Mach number) have been investigated. The direct ion of shock propagation of forward and reverse corotating shocks is q ualitatively consistent with the global 3-D model of Pizzo [1991] whic h predicts that forward shocks will propagate equatorward while revers e shocks propagate poleward. The strongest shocks, are observed at mid -latitudes and are from the south polar coronal hole. These shocks are shown to be supercritical in contrast to the lower latitude sub-criti cal shocks. This change in character of the shocks is likely related t o the intensity of the shock-accelerated energetic particles which als o peaks in the same latitude range.