Which direction is North in Polar map projected images?
The standard parameters used when generating THEMIS Polar Stereographic products approximately align the along-track axis of the image vertically in the resulting projection; when displayed, the start of the image as collected is at the TOP. For images completely collected during the descending orbit node, this is equivalent to the common "north-up" convention; for images completely collected during the ascending orbit node, this is equivalent to "north-down". For images that cross the highest polar regions (i.e. starting during one orbit node and ending during the other node), the north pole will be off to the right or left in the map projection; use the North Azimuth Angle parameter associated with the image to exactly locate the pole.