Neutral Thermospheric Density Retrievals with ICON EUV Spectrometer

Changes in thermospheric density and temperature are driven by competing effects: solar tides and planetary and gravity waves; variations in solar ultraviolet (UV) flux and geomagnetic forcing; and the typical diurnal and seasonal effects. Measurements of thermospheric variability are critical for understanding the nature of ionosphere-thermosphere coupling, and satellite remote sensing is well-suited for this purpose, as it allows for the measurement of altitude profiles while providing global coverage. The Ionospheric Connection Explorer (ICON) measures key thermospheric quantities during the day using far-UV (FUV, passbands of 130-140 nm and 150-160 nm) airglow and ionospheric response using extreme-UV (EUV, 54-88 nm) airglow, each requiring a dedicated instrument. However, recent work has suggested that EUV airglow at 61.6 nm and around 87.8 nm has potential for the retrieval of thermospheric O and N2 density. In this study, we develop and apply an algorithm for such a retrieval using daytime measurements of these emissions using the ICON EUV instrument.