Spectra of the hydroxyl emissions in the wavelength range 1.0-1.6 #m, which originate at
mesopause altitudes, have been obtained, using a Fourier transform spectrometer at Maynooth (53.2Â°N,
6.4Â°W), on all suitable nights during the period January-December 1993. Rotational temperatures and
integrated band brightnesses have been calculated from the spectra of the OH(3, 1) and (4, 2) vibration-
rotation bands. The mean annual temperatures calculated over all measurements were T(3, 1)= 200 + 19
K and T(4, 2)= 206 + 19 K, where the uncertainty represents the standard deviation on the measurements.
Harmonic analysis of the nightly averaged temperature values revealed an amplitude of 27+ 1 K and a
phase of 95 __. 2 days in the annual variation of the (3, 1) band at our latitude. The semiannual component
was found to have an amplitude of 7 _+ 1 K and a phase of - 5 1 ___ 9 days for this band. Results for the (4,
2) band were identical in both amplitude and phase for the annual component, while the semiannual
component gave an amplitude of 8_ 1 K and a phase of - 4 3 + 7 days. These results are compared with
data recorded by the SME satellite, and with the predictions of the MSISE-90 model for a station at 53 Â°
latitude. Temperatures predicted by the MSISE-90 model for Maynooth are consistently below the values
obtained in this study by 15-20 K. Excellent agreement is observed between the absolute value of tempera-
ture, in the case of the SME satellite, and in the amplitude and phase of the annual variation predicted by
MSISE-90. The phase of the semiannual component observed in our data deviates somewhat from the
- 9 9 + 1 days predicted by MSISE-90.
The annual mean brightness of the OH (3, 1) band was found to be 75 + 18 kR, while that of the (4, 2)
band was 106 + 26 kR. Diurnal variations generally showed a steady decrease from dusk to dawn, apart
from a brief period in June and July. Monthly average values of band brightness have been calculated for
each band and are compared with the predictions of a recent photochemical model (Le Texier et al., 1987).
The model shows some elements of agreement with our observations, particularly a pair of maxima near
the equinoxes, but it does not predict the broad winter maximum observed in both bands at this latitude.
Mulligan, F.J. and Horgan, D.F. and Galligan, J.G. and Griffin, E.M. (1995) Mesopause temperatures and integrated band brightnesses calculated from airglow OH emissions recorded at Maynooth (53.2Â°N, 6.4Â°W) during 1993. Journal of Atmospheric and Terrestrial Physics, 57 (13). pp. 1623-1637.