... The Si VIII line width measurements and N e estimates based on SUMER observations are combined with LASCO and UVCS output to provide an overview of its variations with height above a polar coronal hole. ... Combining the Si VIII half width at 1/e of the peak intensity with the UVCS O VI half width, we find a small increase of the half width from 1 to 1.2 , then a plateau until 1.5 , thereafter a sharp increase until 2 , finally a more gradual increase reaching 550 km s -1 at 3.5 . ...