Estimate of N2+ ${\mathrm{N}}_{2}^{+}$ Altitude Profile Using Blue Auroral Resonant‐Scattering 427.8 nm Emission Observed With HySCAI During Astronomical Twilight

Abstract The spectrum of high‐altitude blue auroral emissions was observed with HyperSpectral camera for auroral imaging (HySCAI) during morning astronomical twilight in Kiruna. Auroral resonance scattering of an 1NG (0, 1) (427.8 nm) emission starts to increase from the east, and then the increase of this resonance scattering emission extends to the magnetic zenith. The volume emission rate is evaluated from the rise in resonance scattering emission (time derivative of emission intensity). The volume emission rate of (427.8 nm) reaches its maximum when the sunlight shadow height reaches 200 km, although the GLOW model predicted a peak altitude of (427.8 nm) of 120 km. The higher altitude of the resonance scattering emission peak observed with HySCAI supports the idea that is produced by the charge exchange between and existing at high altitudes. However, we cannot rule out another possible mechanism of upflowing ions.