In the Mesosphere/lower thermosphere (MLT) region of the atmosphere gravity waves dissipate and release their energy and momentum into the region and thereby adding to the momentum budget of the region. These waves also couple and interact with the airglow layers in the atmosphere, for example, causing a secular increase in the concentration of different species involved in the OH chemistry. This particular paper explores how gravity waves affect other major airglow emissions to better understand the variations found. From the virtual experiment of numerical simulations, a statistically significant change in the number density and peak altitude occurred as a direct result of a wave packet passing through the region and the airglow chemistry involved. Through further analysis, the study also shows that O(1s) has the largest wave induced secular variation of around 33%. O(1s) has the largest variation because the wave packets’ amplitude is largest at the O(1s) peak altitude (and the secular variations are proportional to the square of the gravity waves amplitude). When looking at the variations of the OH(8,3) intensity, it has the largest peak to peak amplitude despite O(1s) and O2(0,1) having larger amplitudes of the wave packet. Finally, it is suggested that further experimentation of the branching ratios take place due to findings in this experiment that the branching ratio affects the volume emission rate (VER).

 

Reference: Huang, T.-Y., and R. George (2014), Simulations of gravity wave-induced variations of the OH(8,3), O₂(0,1), and O(¹S) airglow emissions in the MLT region, J. Geophys. Res. Space Physics, 119, 2149–2159, doi:10.1002/2013JA019296.