Temporal variations in the absolute intensity (I) and the rotational temperature (T) of the polar winter airglow OH(8, 3) bands were observed over Longyearbyen, Spitsbergen (78.2¿N), in December 1984. The high latitude of the observatory places it in a continuous polar night around the winter solstice period, thereby permitting 24-hour optical measurements. Spectral analyses of the I and T time series reveal a dominant semidiurnal component and a wave with a period of 3.7 hours. Other waves with shorter periods may be present for part of the total observing period, but the signal-to-noise ratios of their amplitudes averaged over a 24-hour interval are too low to permit definitive identification. The ratio &eegr; of the correlated Fourier components of (I-I¿)/I¿ to that of (T-T¿)/T¿ (an overbar signified time average) has amplitude 3.2¿0.9 and 4.3¿1.3 for the 12- and 3.7-hour waves, respectively, while the phase ϕ of &eegr; for these periods is 6¿¿16¿ and -12¿¿12¿. The value of &eegr; for the 3.7-hour wave can be compared with the theoretical prediction of &eegr; for gravity wave modulation of the OH emission. For an emission height of 87 km and an atomic oxygen scale height H(O) of -2 km, theory gives ‖&eegr;‖=4.2 and ϕ=0¿ for the 3.7-hour wave, in good agreement with the observation. The theoretical interpretation of &eegr; at the 12-hour period is complicated by the likelihood that the observed semidiurnal oscillation is not a simple tide. For tidal modulation of the OH nightglow, theory gives ‖&eegr;‖ between 2.6 and 0.9 and ϕ between 0¿ and 10¿ for high-order semidiurnal modes and for the same values of emission height and H(O) as above. ¿ American Geophysical Union