CMEs at High Northern Latitudes During Solar Maximum : Ulysses and SOHO Correlated Observations.

From September through November 2001, Ulysses was almost continuously immersed in polar coronal hole (CH) flow during its northern polar pass of the Sun. For much of this time, the flow was fast (> 700 km/s) and steady, quite similar to the steady unstructured flow observed during Ulysses first polar orbit near solar minimum. During the three months Ulysses transited the northern polar CH it observed 5 coronal mass ejections (CMEs). Of these, two were clearly over-expanding and two were at least partially driven by overexpansion. The phenomenon of over-expansion was frequently observed at high latitudes during Ulysses first orbit. The recurrence of over-expanding CMEs during the second orbit at high latitudes indicates that this is a phenomenon apparently unique to and typical of CMEs embedded in polar CH flow. Ulysses was nearly above the solar limb during this three-month interval, providing an opportunity to use LASCO/SOHO observations to study the initial velocity profiles of the CMEs observed further out by Ulysses. These initial conditions were used as inputs into a hydrodynamic code, the results of which are reported here