Low latitude mesospheric molecular oxygen profiles from Lyman-alpha absorption measurements from Thumba

Abstract

Molecular oxygen profiles of the low latitude atmosphere were investigated using the results of rocket-borne Lyman alpha absorption. Measurements of oxygen concentrations over the rocket launching station at Thumba, India at the 65-85 km altitude were derived from values of the absorption of solar hydrogen Lyman alpha in the upper atmosphere. A second order polynomial fits observations made with a CIRA model at 82.5 km; below this altitude, the measured molecular oxygen densities are lower than the values computed from the model. Oxygen concentrations were 40% greater with an increase in the solar flux level from 104 to 171; the O2 concentrations in daytime were consistent with the long term variation with solar activity in neutral atmospheric densities at mesospheric heights.