JOP 158 The Fast Solar Wind from 1.05 to 4 Ro. Responsible Scientists : E. Antonucci and A. Gabriel Version updated 21.5.2002 Participating : S. Giordano, F. Bely-Dubau, A. Fludra, P. Lemaire, etc, ... Scientific rationale The fast solar wind can be studied above the limb in coronal holes. During solar minimum, well-formed holes are to be found above the poles. These were the object of several good observations during the period 1996-1998, of which we cite notably the JOP2 observations, which have yielded some very good data-sets. Now, in 2002, holes are again beginning to form above the poles. Although it will be some time before these are really stable, it is now time to begin trying new sequences to add to our understanding of this region. With a SUMER capable of rastering, the 1996 sets were able to provide good data on the electron temperature as a function of height and, at greater heights, the flow velocities through Doppler Dimming. However, the real calibration of these velocities and their extension to lower heights are limited by the lack of simultaneous density measurements. Another parameter, which remains only poorly understood is the role of polar plumes in these diagnostics. Are we looking at a 2-component plasma? and what are plumes anyway? With the return of polar holes, we plan to extend these measurements throughout the height range, ensuring the complementary density measurements and, in spite of the restricted movement possible with SUMER, tackle some of the remaining unknowns. Initial studies with this JOP may be limited by the low quality of the polar holes, but this is expected to improve steadily with the cycle. Scientific objectives We need to measure the radial outflow velocity, the different ion kinetic "temperatures" and the electron temperature, as a function of the height, above the polar coronal hole. Specifically, for each instrument : SUMER. This will alternate two sequences, each looking at the region from the limb out to 1.3Ro or further, near x=0. The first of these will record the range including O VI 1032/1038, and Lyman beta, with the object of measuring accurately the oxygen multiplet line ratio and interpreting it in terms of the Doppler dimming velocity. This requires a precision correction for the stray light from the telescope. We have recently acquired an increased confidence in our ability to do this correction, using the code developed by David and verified by the above limb observations of Lyman beta. Interlaced with these sequences, we run, with the same geometry, a sequence of observations of the density-sensitive multiplet ratio of Si VIII near 1400 A. As the Sun rotates on successive days, we hope to see plume and interplume regions go past the slit position. These sequences will be run for a period of around 3 hours, starting at 20:00 hours on each observing day. UVCS. This will observe from 1.5 to 4 Ro, scanning radially outwards through the hole. It will measure O VI, Si XII and H I, for the flow velocities and the ion kinetic temperatures. The sequence will last 24 hours(with a gap of 4 hours in the middle to perform synoptic studies), on account of the low intensity in this region and will start around 17:00 on each day of observation. For CDS, we will aim to raster an area of 4x4 arcmin near x=0, just including the limb. The sequence chosen aims to verify the global electron temperature by observing the ionisation balance. EIT can support this JOP by observing the importance of nearby active regions and the coronal hole boundaries, using its normal CME Watch full-disk images in 195 A. LASCO images over the complete solar rotation are important for establishing the streamer geometry, but these can be obtained in the normal synoptic program. Scheduling The first runs are proposed during the MEDOC 9 campaign, week 27 May-2 June 2002. In order to reduce possible conflict with MEDOC/Ground-based observations, it is proposed to schedule the CDS and SUMER observations between 18:00 and 24:00 UT each day for 7 days.