Technique to retrieve solar EUV flux and neutral thermospheric O, O2, N2, and temperature from airglow measurements

We describe a method for retrieving neutral thermospheric composition and solar EUV flux from optical measurements of the O(+)(P-2) 732 nm and O(D-1) 630 nm airglow emissions. The parameters retrieved are the neutral temperature, the O, L2, and N2 density profiles, and a scaling factor for the solar EUV flux spectrum. The temperature, solar EUV flux scaling factor, and atomic oxygen density are first retrieved from the 732 nm emission, which are then used with the 630 nm emission to retrieve the O2 and N2 densities. Between the altitudes of 200 and 400 km the retrieval technique is able to statistically retrieve values to within 3.1% for thermospheric temperature, 3.3% for atomic oxygen, 2.3% for molecular oxygen, and 2.4% for molecular nitrogen. The solar EUV flux scaling factor has a retrieval error of 5.1%. We also present the results of retrievals using existing data taken from both groundbased and spacebased instruments. These include airglow data taken by the Visible Airglow Experiment on the Atmospheric Explorer spacecraft and the Imaging Spectrometric Observatory flown on the ATLAS 1 shuttle mission in 1992.