The influence of travelling ionospheric disturbances on the night airglow emissions

Quasi-periodic variations in the intensity of the OK6300A night airglow emission observed at Camden and Culgoora, N.S.W. are described. For periods of 40 m to 120 m, they are shown to be closely related to variations in h'F recorded on a local ionosonde. Cases in which the pattern of the h'F variations observed during a night was evident at a number of stations in the Australian Ionospheric Prediction Service network indicated disturbances travelling equatorward at speeds in the range 300 m/s to 700 m/s. These disturbances were considered to be due to the now well-known gravity waves propagating equatorward from the auroral oval during magnetic storms. Occasionally similar periodic intensity variation patterns appeared in both the 6300A and 5577A emissions during the passage of a gravity wave (as indicated by h'F) and such cases are also considered. Coinciding airglow intensity and h'F periodic variations were also observed under quiet magnetic conditions. The sources of the gravity waves causing these were not located. Processes causing the airglow intensity variations during the passage of gravity waves are discussed. (author)