Sure.
Red: It is the lower concentration of oxygen but also/mostly the lower overall pressure (lower number of partciles per volume). Only with lower pressure can there be fewer collisions and thus the exited state is not quenched.
Green: Any interaction of a random atom and the exited oxygen atom, that would otherwise emit red light, quenches the red light emission. Thus the faster green transition can take over.
Could you correct it for us mere mortals without in-depth aurora knowledge?
Sure. Red: It is the lower concentration of oxygen but also/mostly the lower overall pressure (lower number of partciles per volume). Only with lower pressure can there be fewer collisions and thus the exited state is not quenched.
Green: Any interaction of a random atom and the exited oxygen atom, that would otherwise emit red light, quenches the red light emission. Thus the faster green transition can take over.