Ionospheric electron content and NmF2 from nighttime OI 135.6 nm intensity

This paper derives the theoretical relationship between vertical integrated intensity of OI 135.6 nm oxygen emission with integrated electron content (IEC) from 150 to 800 km altitude as well as F layer peak electron density (NmF2). Local time, seasonal, and solar cycle dependence of the relationship is investigated, and it is proposed as a conversion factor to retrieve IEC and NmF2 values from airglow measurements. The errors associated with the IEC and NmF2 estimation using the derived conversion factor are demonstrated for different local times and solar activity. The theoretical conversion factor is compared with that calculated using airglow measurements by the Global Ultraviolet Imager onboard the Theremosphere, Ionosphere, Mesosphere Energetics and Dynamics mission and the Global Ionospheric Map total electron content as well as the nadir integrated OI 135.6 nm intensity by the Tiny Ionospheric Photometer and NmF2 determined from the Global Positioning System Occultation Experiment, both onboard FORMOSAT-3/COSMIC.