OH^{<> \}(7-5) Meinel band dayglow and nightglow measured by the SME limb scanning near infrared spectrometer: comparison of the observed seasonal variability with two-dimensional model simulations

The OH^*(7-5) mesospheric hydroxyl emission was monitored at 1.89 micron by the near infrared spectrometer on board of the Solar Mesosphere Explorer satellite (SME). The vertical distributions of monthly averaged dayglow and nightglow radiances are in general agreement with theoretical calculations, suggesting that the current understanding of the dominant airglow mechanism is substantially correct. Averages over one or two months display recurrent variations from one year to the next at low and mid-latitudes, indicating a seasonal cycle. These seasonal variations are compared with the theoretical predictions of a two-dimensional dynamical/chemical model wherein the seasonal and latitudinal variations in diffusion induced by breaking gravity waves are explicitly considered. -from Authors