Solar wind speed at the source surface (R=5Rs).
The crosses mark the daily position of the subearth point on the maps (Sun). Since the Sun's rotation axis is inclined 7.25o to the ecliptic, over the course of a year the subearth point varies (in latitude) from +7.25o above to -7.25o below the Sun's equator.
The x-axis is Carrington Longitude in degrees. Carrington Rotation
Numbers are also shown. The most recent data are located at the far left of
the map.