ULYSSES out-of-ecliptic observations of interplanetary shocks.

Abstract

Interplanetary shocks observed at the Ulysses spacecraft as it traveled from the ecliptic plane to the southern solar pole have been identified and analyzed using both magnetic field and plasma measurements. The latitude dependences of various parameters associated with the shocks (beta, θ_BN_ and Mach number) have been investigated. The direction of shock propagation of forward and reverse corotating shocks is qualitatively consistent with the global 3-D model of Pizzo [1991] which predicts that forward shocks will propagate equatorward while reverse 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-critical shocks. This change in character of the shocks is likely related to the intensity of the shock-accelerated energetic particles which also peaks in the same latitude range.