Has the corotation component been taken into account in the flow data?
Because the Earth rotates beneath the spacecraft’s track, there is an eastward flow component in the raw data (in the nonrotating frame). However, almost all other data observations and analysis of the ionosphere (e.g. Earth-based radars) are done in the corotating frame (the frame of reference rotating with the Earth). So for each four-second set of data we calculate the eastward flow at the spacecraft’s altitude, then remove that vector component from the horizontal ion flow data (VX and VY). A more detailed description of this procedure is available here.
