Scientific papers on Purple Twillight/sunlit Auroras

[Gabriel Hofstra]

During the time after sunset (even a while after astronomical night) and before sunrise, the aurora can sometimes show a purple color over the green one. I like to call them Twillight Auroras. It's easiest to see them on locations near the aurora oval as auroras normally appear there.

My question: Is there any scientific papers or good resources on the internet about twillight auroras to citate from?

I haven't found a single website or scientific paper describing the twillight auroras in detail.

 

My main theory and what I have heard is that twillight auroras get their purple color in the upper auroral line from the sunlight. Probably what happens here is UV rays colliding with already excited nitrogen atoms, or am I way outside the path?

[helios]

I think solar UV is not energetic enough to cause visible emissions in the atmosphere.
Atoms and molecules have discrete emission wavelengths, they can't change color.

A combination of excited N2+(blue-ish) and N2 (red) results in a pink/purple color, perhaps that is what you mean.
https://aurora.live/2020/04/aurora-borealis-colors-explained/