Observations of sunlit N₂⁺ aurora at high altitudes during the RENU2 flight

Abstract. We present measurements of sunlit aurora during the launch of the Rocket Experiment for Neutral Upwelling 2 (RENU2) on the 13th of December 2015 at 07:34 UT. The in situ auroral conditions coincide with those of sunlit aurora, and were characterised by the 391.4 nm and 427.8 nm N₂⁺ emissions. A correlation between several auroral wavelengths, as measured by a meridian scanning photometer was used to detect sunlit aurora and indirectly neutral upwelling. These results, based on ground data, agree well with the RENU2 measurements recorded during its pass through the sunlit polar cusp. Using data from RENU2 and the solar photon flux, it was found that sunlit aurora was a major part (≈ 40 %) of the observed 427.8 nm emission.