On the effects of atmospheric gravity waves on profiles of H, O₃, and OH emission

Abstract

The effect of gravity waves on H and O3 profiles is investigated using a gravity wave model, valid for an inhomogeneous atmosphere. The consequent effect on OH emission is also considered using Good's data for the ‘undisturbed’ profiles. The results show that (1) the magnitude of the response depends on the relative magnitudes and signatures of the vertical and horizontal wave‐induced flux. Since in some regions the horizontal velocity field of the gravity wave can increase much more rapidly with height than the vertical field, horizontal flux can in some instances overcome the vertical even when there is a relatively sharp layer gradient. (2) The structures in the OH profile produced by the gravity wave are in general, but not always, more pronounced below the intensity peak than above. The observed dark areas on OH emission can be produced by gravity waves with vertical wavelength small compared with the half width of the intensity profile.

On nonlinear response of minor species with a layered structure to gravity waves

“…[24] In the present work we have employed a Chapmanlike function as a generic profile to model the unperturbed background number density of minor species such as O 3 and H. The vertical profiles of H and O 3 are taken from Hatfield et al [1981]. To obtain the OH volumetric emission rate profile, we assume that these two species provide SIA the primary mechanism for producing vibrationally excited OH, which can be readily obtained by multiplying these two number densities together.…”

“…whereṼ m , the velocity of the minor species, is assumed to be equal to the gravity wave velocity because collision frequencies between minor and major species are large in this region of the atmosphere [Chiu and Ching, 1978;Hatfield et al, 1981;Gardner and Shelton, 1985]. Chiu and Ching [1978] and Hatfield et al [1981] considered the linear response only, so naturally no secular terms would arise from nonlinearity.…”

“…Chiu and Ching [1978] and Hatfield et al [1981] considered the linear response only, so naturally no secular terms would arise from nonlinearity. Gardner and Shelton [1985] did consider nonlinear response; however, their treatment is valid for a short duration of time and is not applicable for long times because a secular term survives after the time averaging (see their equation 44).…”

“…One specific example is the interaction of atmospheric gravity waves with the minor species responsible for the OH Meinel airglow emission. The OH infrared emission has received considerable attention in recent airglow publications [Hatfield et al, 1981;Myrabo et al, 1983;Taylor et al, 1987;Walterscheid et al, 1987;Schubert and Walterscheid, 1988;Makhlouf et al, 1995].…”

“…[4] There have been numerous modeling studies of the response of minor species to the passage of a gravity wave [Thome, 1968;Chiu and Ching, 1978;Weinstock, 1978;Hatfield et al, 1981;Gardner and Shelton, 1985;Hickey, 1988;Isler et al, 1991;Walterscheid et al, 1994]. However, most of them have focused on linear effects only.…”