Rapid variations in hydroxyl emission

A technique is described for recording the hydroxyl emission spectrum with exposures of 30 sec or more with the aid of a multistage image converter. The temporal variation of rotational temperature and total intensity in the (9, 5) and (4, 1) hydroxyl bands during two hours on one night is plotted using data obtained with 4-min exposures. The ratio of total intensities in these two bands is calculated, and the OH 'vibrational temperature' is derived. It is suggested that rapid variations in hydroxyl emission intensity may be caused by some adiabatic process, such as the passage of internal gravity waves through the mesosphere or horizontal and vertical atmospheric circulation