Conditions for the photochemical destabilization of gravity waves in the mesopause region

This paper investigates the conditions under which gravity waves become uns table due to photochemical heating in the mesopause region. The study shows that the gravity wave growth rate induced by photochemistry is sensitive t o the temperature and atomic oxygen concentration profiles. There is also a strong dependence on the background vertical eddy diffusion coefficient. G ravity waves with longer vertical and/or shorter horizontal wavelengths are less affected by diffusion and can more easily become destabilized through photochemistry. For moderately strong diffusion coefficients (100 m(2) s(- 1)), photochemical destabilization occurs only for fairly long vertical wav elengths, even under the more unstable conditions of cool temperatures and high atomic oxygen density. (C) 2001 Elsevier Science Ltd. All rights reser ved.