Daytime observation of the sodium layer with a Fabry‐Perot spectrometer at Mawson, Antarctica

The first ground based measurements of temperature in the sodium layer at about 90 km altitude in the Antarctic have been made at Mawson; a mean value of 153 ± 7 K for January 1989 was obtained. A dual, scanning Fabry‐Perot spectrometer was used to record the D2 spectral line resonantly scattered from sunlight; the Doppler width and shift of the line measures the kinetic temperature and wind velocity in the emitting region. The technique is shown to be promising for study of the dynamics of the 90 km region which is otherwise difficult to observe.