The altitude of green OI 557.7gnm and blue N2+ 427.8gnm aurora

Abstract

We have performed a large statistical study of the peak emission altitude of green O(1D2-1S0) (557.7gnm) and blue N2+ 1gN (427.8gnm) aurora using observations from a network of all-sky cameras stationed across northern Finland and Sweden recorded during seven winter seasons from 2000 to 2007. Both emissions were found to typically peak at about 114gkm. The distribution of blue peak altitudes is more skewed than that for the green, and the mean peak emission altitudes were 114.84g±g0.06 and 116.55g±g0.07gkm for green and blue emissions, respectively. We compare simultaneous measurements of the two emissions in combination with auroral modelling to investigate the emission production mechanisms. During low-energy electron precipitation (