Simulations of airglow variations induced by the CO₂ increase and solar cycle variation from 1980 to 1991

Airglow intensity and Volume Emission Rate (VER) variations induced by the increase of CO₂ gas concentration and F10.7 variation (used as a proxy for the 11-year solar cycle variation) were investigated for the period from 1980 to 1991, encompassing a full solar cycle. Two airglow models are used to simulate the induced variations of O(¹S) greenline, O₂(0,1) atmospheric band, and OH(8,3) airglow for this study. The results show that both the airglow intensities and peak VERs correlate positively with the F10.7 solar cycle variation and display a small linear trend due to the increase of CO₂ gas concentration. The solar-cycle induced airglow intensity variations show that O(¹S) greenline has the largest variation (~26%) followed by the O₂(0,1) atmospheric band (~23%) and then OH(8,3) airglow (~8%) over the 11 year timespan. The magnitudes of the induced airglow intensity variations by the increase of CO₂ gas concentration are about an order of magnitude smaller than those by the F10.7 solar cycle variation. In general, the F10.7 solar cycle variation and CO₂ increase do not seem to systematically alter the VER peak altitude of the airglow emissions, though the OH(8,3) VER peak altitude moves up slightly during the years when the F10.7 value falls under 100 SFU.