First results from the retrieved column O/N2 ratio from the Ionospheric
Connection Explorer (ICON): Longitudinal structures induced by
nonmigrating tides
Abstract
In near-Earth space, variations in thermospheric composition have
important implications for thermosphere-ionosphere coupling. The ratio
of O to N2 is often measured using far-UV airglow
observations. Taking such airglow observations from space, looking below
the Earth’s limb allows for the total column of O and N2
in the ionosphere to be determined. While these observations have
enabled many previous studies, determining the impact of non-migrating
tides on thermospheric composition has proved difficult, owing to a
small contamination of the signal by recombination of ionospheric
O+. New ICON observations of far UV are presented
here, and their general characteristics are shown. Using these, along
with other observations and a global circulation model we show that
under certain circumstances the impact of non-migrating tides on
thermospheric composition can be observed. By comparing the amplitude of
the variation seen with that in the model, both the utility of these
observations and a pathway to enable future studies is shown.