A modeling study of O₂ and OH airglow perturbations induced by atmospheric gravity waves

Abstract

[1] A one-dimensional model is used to investigate the relations between gravity waves and O 2 and OH airglows perturbations. The amplitude and phase of the airglow perturbations induced by gravity waves (with period > 20 min) are calculated for different vertical wavelength (10-50 km) and damping rate. The model shows that for vertically propagating gravity waves, the amplitude of airglow perturbations observed from ground is larger for longer vertical wavelength, because of the smaller cancellation effect within each layer. The ratio of the amplitudes between O 2 and OH is smaller for larger wave damping. For upward propagating (downward phase progression) waves, the intensity perturbation in O 2 leads OH, and their phase difference (O 2 minus OH) is larger for smaller vertical length and/or stronger damping. The rotational temperature perturbation leads intensity perturbation in both layers. Their phase difference is also larger for smaller vertical length but is smaller for stronger damping. Based on these relations, the vertical wavelength and damping rate of gravity waves can be derived from simultaneous measurements of airglow perturbations in O 2 and OH layers.

Atmospheric wave induced O<sub>2</sub> and OH airglow intensity variations: effect of vertical wavelength and damping

“…The negative trend indicates that when the phase difference is small, normally for a longer period of oscillation, the ratio is high, i.e., larger amplitude of variation in O 2 than that of OH. According to the model calculations of Liu and Swenson (2003) and Vargas et al (2007), the phase difference between the two emissions is a function of vertical wavelength. It is not sensitive to the period of variation (Vargas et al, 2007).…”

“…Recently Taori et al (2007) demonstrated the variability of wave growth rate from the OH and O 2 emission intensity temporal variations. Liu and Swenson (2003) and Vargas et al (2007) first tried to estimate the damping rate by using O 2 and OH emission intensity variations in their atmospheric models. The wave damping rate β can be defined in a term of wave amplitude:…”

“…Taori et al (2007) pointed out the effects of wave growth and dissipation in the O 2 and OH emissions. Liu and Swenson (2003) pointed out that η depends on the vertical wavelength and also the wave damping effect. From their model calculation, they further suggested that the vertical wavelength and damping rate of gravity waves can be derived from the simultaneous measurements of the O 2 and OH emission rates.…”

“…Many works on the gravity wave and tides using the η values have been written Hickey, 1988a, b;Reisin and Scheer, 1996;Taori and Taylor, 2006). However, η includes various other unknown parameters, such as the variation of local oxygen photochemistry (Hickey et al, 1993), and height variation of the emission layer which affects emission rates and temperature directly (Liu and Swenson, 2003;Vargas et al, 2007).…”

Recent progress in mesospheric gravity wave studies using nigthglow imaging system

“…Simultaneous wind measurements (not shown) have been used to determine the intrinsic wave period and to show that this wave was freely propagating (using the "vertical wave number squared" method described by Isler et al, 1997). Using these data an estimate of the horizontal momentum flux of this quasi-monochromatic wave can be obtained using the method described in Liu & Swenson (2003). Using an estimated BruntVaisala period of 5 min (derived from simultaneous Na lidar temperature data), the magnitude of the momentum flux was found to be 30 ± 10 m 2 /s 2 .…”