Abstract
Nitrogen is the most abundant element in the Earth’s atmosphere. Around
78% N2; and 21% O2; form the air we breathe and expand into
high-altitude atmosphere, the thermosphere, and eventually the
ionosphere. The neutral molecules in the ionosphere are ionized by solar
radiation, and some of them break up into atoms, and others become
charged particles. The ionospheric ions with sufficient energy can flow
out into space, and the abundances of these outflowing ionospheric ions
highly impact the near-Earth plasma properties. Studies focused on
outflowing O+ ions have been conducted for many years. However, the
contribution of N+ to the outflow solution is still largely unknown due
to the instrumental limitations. We developed a first-principled physics
model to understand how N+ and molecular ions, including NO+, N2+, and
O2+, acquire the sufficient energy to escape Earth’s atmosphere. This
study reveals the importance of N+ ions in the high-altitude polar
ionosphere, from few hundred kilometers to thousands of kilometers in
the space, and examines the possible mechanisms to accelerate and
removed them from Earth’s atmosphere.