Traditional approaches for capturing auroral altitude profiles relied on stereoscopic imaging with multiple cameras, but the new technique applies fine-grained spectral separation obtained from hyperspectral data. This enables discrimination between reflected sunlight and auroral emissions even under the complex light conditions of astronomical twilight.
The study focused on blue aurora events in Kiruna, Sweden, on October 21, 2023. The researchers mapped the altitude profile of nitrogen molecular ions (N2?), principal contributors to auroral emissions. While typical nighttime aurora displays peak emissions near 130 kilometers, the twilight observation revealed a maximum emission intensity at 200 kilometers. This finding suggests that nitrogen molecular ions occur at unexpectedly high altitudes during dawn conditions.
This breakthrough supports previous indications that high-altitude nitrogen molecular ion density is greater than previously understood. The results permit improved testing of auroral formation models and demonstrate the critical advantage of hyperspectral cameras - providing precise altitude and time-resolved measurements.
Ongoing research aims to address open questions in ionospheric chemistry, particularly regarding the origin and movement of nitrogen molecular ions. Future collaborations will extend these findings globally.
Research Report:Estimate of N2+ altitude profile using blue auroral resonant-scattering 427.8mn emission observed with HySCAI during astronomical twilight
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