Datensatz

Zusammenfassung

The Meinel band (at 1103 to 1134 nm) is solely attributed to the electron bombardment and, therefore, manifests electron precipitations and accelerations driven by the MIT coupling. In preparation for the BALBOA balloon mission of imaging aurora in sunlight, we have developed four near-infrared (NIR) camera systems to examine the morphology and dynamics of N2+ Meinel 0-0 aurora from a high-altitude balloon under the sun. We have run several ground-based observing campaigns in conjunction with a set of optical and radar diagnostics at Poker Flat Research Range (PFRR) to examine NIR cameras’ performance. The PFRR digital all-sky camera regularly operates three filters to image the O(1D) emission at 630.0 nm, the O(1S) emission at 557.7 nm, and the N2+ first negative band at 427.8 nm. This offers a unique opportunity to examine the use of N2+(M) as a diagnostic for energy flux and average energy with other near-infrared and visible emissions. We captured splendid auroras in all emissions during a few moderate substorms, which enabled us to compare the auroral morphology between N2+(M) and O(1D) and the ratios of N2+(M)/N2+(1N) and O(1D)/N2+(1N). The morphologies can reveal the electron precipitation mechanisms in the magnetosphere because hard and soft electrons generate N2+(M) and O(1D) at different altitudes. Since the N2+(1N) emission caused by the photoionization and Rayleigh resonant scattering of sunlight can be ignored in midwinter nighttime, the ratios provide a comparison of estimated electron characteristic energy. The paper also discusses the MIT coupling responsible for the observed auroral dynamics.