A Survey of Daytime Ionospheric O+ From ICON

The NASA Ionospheric Connection Explorer (ICON) was launched in October 2019. ICON includes an Extreme Ultraviolet (EUV) imaging spectrograph that measures the daytime ionospheric O⁺ via altitude profiles of the OII 83.4 and 61.7 nm airglow emissions. The method is based largely on an algorithm developed at NRL for the Special Sensor Ultraviolet Limb Imager (SSULI), and evolved based on data collected by the Remote Atmospheric and Ionospheric Detection System (RAIDS) and the Limb-imaging Ionospheric and Thermospheric EUV Spectrograph (LITES) that both flew aboard the International Space Station at an orbit altitude of ~410 km. The ICON data represent the first application of this technique to a comprehensive set of measurements made across all local daytime sectors from a vantage point (orbit altitude ~600 km) above the bulk of the ionospheric content. However, these are also the first such measurements made during solar minimum conditions, a decidedly challenging environment for such a remote sensing approach. We will present a survey and assessment of these ICON measurements and ionospheric retrievals that have been made to date, across local times and through seasons in this first year of operations.