Remote sensing of nighttime F region peak height and peak density using ultraviolet line ratios

We present a newly developed algorithm for simultaneously inferring the peak height and peak density of the O + ions in the nighttime ionosphere. The technique relies on the simultaneous observation of the emissions of atomic oxygen at 130.4 and 135.6 nm that are primarily produced by radiative recombination, a natural decay process of the ionosphere. The 135.6 nm emission has become the workhorse for sensing O + distribution from space from low-Earth platforms where it has been used to infer the peak electron density.