the reconstruction uncertainties [@Inhester:2006] calculated by assuming a maximal 3 Mm variation of the plume axis position. The resulting uncertainties are directed mainly half way between the view directions of *STEREO A* and *B*, and are considerable for the data set in April since the spacecraft separation angle was small at that time. With the increased separation angle in June, the uncertainties are greatly reduced for the same assumption of 3 Mm uncertainty in 2D.

The polar view of the ten plumes projected onto the solar equatorial plane is shown in Figure \[fig:top\_view\]. Larger symbols indicates the plume positions at greater heights above the solar surface. All ten plumes oriented close to their local meridian planes and inclined away from the rotation axis.

### Plume’s orientation analysis

In Figure \[fig:plume\_geometry\] a sketch of the 3D plume geometry is presented to analyse the plume orientation. The relevant results is shown in Table \[tab:parameter\]. Concerning the latitudes and longitudes of the plume footpoints, all the plumes are located within a latitude cone of $20^\circ$ around the pole. For a better estimate of the outflow speeds along the plumes from FUV (Far Ultraviolet)/ EUV spectral observations by SUMER and UVCS on board SOHO, 