COMPARISON OF THEORIES FOR GRAVITY-WAVE INDUCED FLUCTUATIONS IN AIRGLOW EMISSIONS

A comparison is undertaken of theories for the gravity wave induced fl uctuations in the intensity of airglow emissions and the associated te mperature of the source region. The comparison is made in terms of Kra ssovsky's ratio eta(E) for a vertically extended emission region (eta( E)) is the ratio of the vertically integrated normalized intensity per turbation to the vertically integrated normalized intensity-weighted t emperature perturbation). It is shown that the formulas for eta(E) in the works by Tarasick and Hines (1990) and Schubert et al. (1991) are in agreement for the case of an inviscid atmosphere. The calculation o f eta(E) using the theory of Tarasick and Hines (1990) requires determ ination of their function chi; we show that chi is simply related to t he ''single-level'' Krassovsky's ratio eta of Schubert et al. (1991). The general relationship between chi and eta is applied to a simple ch emical-dynamical model of the O2 atmospheric airglow and the altitude dependence of these quantities is evaluated for nonsteady state chemis try. Though the Tarasick and Hines (1990) formula for eta(E) does not explicitly depend on the scale heights of the minor constituents invol ved in airglow chemistry, eta(E) implicitly depends upon these scale h eights through its dependences on chemical production and loss contain ed in chi. We demonstrate this dependence of eta(E) for the OH nightgl ow on atomic oxygen scale height by direct numerical evaluation of eta (E); in this case the dependence originates in the chemical production of perturbed ozone.