OPTICAL OBSERVATIONS OF GRAVITY-WAVES IN THE AURORAL-ZONE

Night-time observations of O(1D) lambda630 nm and O(1S) lambda558 nm t hermospheric emissions were made at Mawson, Antarctica (67.6-degrees-S , 62.9-degrees-E) from 1982 to 1989, using a three-field photometer. C ross-spectral analysis of the data was used to extract frequencies and horizontal trace velocities of periodic structures. Structures in the lambda630 nm emission were characteristic of large-scale waves, and t hose in the lambda558 nm emission were characteristic of medium-scale waves. The results showed distinct polarisation of the propagation azi muths; waves in the lambda630 nm emission propagated approximately nor thwestward throughout the 8 yr period, whilst propagation azimuths of waves in the lambda558 nm emission appeared to be solar-cycle-dependen t. It is suggested that waves observed in the lambda630 nm emission we re of predominantly auroral electrojet origin, whilst those observed i n the lambda558 nm emission were of both auroral and tropospheric orig in.