Direct observations of thermospheric winds during geomagnetic storms

Direct measurements of thermospheric winds were made during two geomagnetic storms. Winds were detected (a) in the stable auroral red arc of October 31 to November 1, 1968, and (b) during the aurora of May 14–15, 1969. In both storms the measured winds were from the north and persisted throughout the night with a velocity between 250 and 400 m sec−1. The winds were measured with a ground-based Fabry-Perot interferometer from the Doppler shift of two λ6300 fringe profiles. One fringe profile was obtained in the zenith where the component of the wind along the line of sight of the instrument is small. The other fringe profile was obtained at a high zenith angle where a component of the horizontal wind exists along the line of sight of the instrument.