Investigation of ionospheric O+ remote sensing using the 834‐Å airglow

Abstract

We have studied the feasibility of ionospheric O+ remote sensing through measurements of the 834‐Å airglow. Our approach uses discrete inverse theory (DIT) to retrieve O+ number density profiles from the airglow. Our tests of this method assume observations by a limb‐scanning system on an orbiting satellite at an altitude of 850 km. The scans cover the range of 10°–26.5° below horizontal, consistent with future multiyear missions. To provide a baseline assessment, we represent the synthetic ground truth (“true”) O+ distribution as a generalized Chapman‐type profile with three or more parameters, based on our recent analysis of topside incoherent scattering radar data and standard ionospheric models (International Reference Ionosphere 1990 (IRI‐90) and the parameterized ionospheric model (PIM)). The DIT method proves to be robust, converging to an accurate solution for a wide variation in ionospheric profiles. Using a detailed statistical error analysis of synthetic limb intensity data derived from the IRI‐90 and PIM models, we work a difficult test case following from recent comments on the concept of 834–Å remote sensing of ionospheric O+. We find that the DIT method can correctly distinguish between distinctly different F layers that produce nearly identical intensity profiles, consistent with instrument specifications for future missions.